1 /* C-compiler utilities for types and variables storage layout
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
30 #include "stringpool.h"
34 #include "diagnostic-core.h"
35 #include "fold-const.h"
36 #include "stor-layout.h"
38 #include "print-tree.h"
39 #include "langhooks.h"
40 #include "tree-inline.h"
46 /* Data type for the expressions representing sizes of data types.
47 It is the first integer type laid out. */
48 tree sizetype_tab[(int) stk_type_kind_last];
50 /* If nonzero, this is an upper limit on alignment of structure fields.
51 The value is measured in bits. */
52 unsigned int maximum_field_alignment = TARGET_DEFAULT_PACK_STRUCT * BITS_PER_UNIT;
54 static tree self_referential_size (tree);
55 static void finalize_record_size (record_layout_info);
56 static void finalize_type_size (tree);
57 static void place_union_field (record_layout_info, tree);
58 static int excess_unit_span (HOST_WIDE_INT, HOST_WIDE_INT, HOST_WIDE_INT,
60 extern void debug_rli (record_layout_info);
62 /* Given a size SIZE that may not be a constant, return a SAVE_EXPR
63 to serve as the actual size-expression for a type or decl. */
66 variable_size (tree size)
69 if (TREE_CONSTANT (size))
72 /* If the size is self-referential, we can't make a SAVE_EXPR (see
73 save_expr for the rationale). But we can do something else. */
74 if (CONTAINS_PLACEHOLDER_P (size))
75 return self_referential_size (size);
77 /* If we are in the global binding level, we can't make a SAVE_EXPR
78 since it may end up being shared across functions, so it is up
79 to the front-end to deal with this case. */
80 if (lang_hooks.decls.global_bindings_p ())
83 return save_expr (size);
86 /* An array of functions used for self-referential size computation. */
87 static GTY(()) vec<tree, va_gc> *size_functions;
89 /* Return true if T is a self-referential component reference. */
92 self_referential_component_ref_p (tree t)
94 if (TREE_CODE (t) != COMPONENT_REF)
97 while (REFERENCE_CLASS_P (t))
98 t = TREE_OPERAND (t, 0);
100 return (TREE_CODE (t) == PLACEHOLDER_EXPR);
103 /* Similar to copy_tree_r but do not copy component references involving
104 PLACEHOLDER_EXPRs. These nodes are spotted in find_placeholder_in_expr
105 and substituted in substitute_in_expr. */
108 copy_self_referential_tree_r (tree *tp, int *walk_subtrees, void *data)
110 enum tree_code code = TREE_CODE (*tp);
112 /* Stop at types, decls, constants like copy_tree_r. */
113 if (TREE_CODE_CLASS (code) == tcc_type
114 || TREE_CODE_CLASS (code) == tcc_declaration
115 || TREE_CODE_CLASS (code) == tcc_constant)
121 /* This is the pattern built in ada/make_aligning_type. */
122 else if (code == ADDR_EXPR
123 && TREE_CODE (TREE_OPERAND (*tp, 0)) == PLACEHOLDER_EXPR)
129 /* Default case: the component reference. */
130 else if (self_referential_component_ref_p (*tp))
136 /* We're not supposed to have them in self-referential size trees
137 because we wouldn't properly control when they are evaluated.
138 However, not creating superfluous SAVE_EXPRs requires accurate
139 tracking of readonly-ness all the way down to here, which we
140 cannot always guarantee in practice. So punt in this case. */
141 else if (code == SAVE_EXPR)
142 return error_mark_node;
144 else if (code == STATEMENT_LIST)
147 return copy_tree_r (tp, walk_subtrees, data);
150 /* Given a SIZE expression that is self-referential, return an equivalent
151 expression to serve as the actual size expression for a type. */
154 self_referential_size (tree size)
156 static unsigned HOST_WIDE_INT fnno = 0;
157 vec<tree> self_refs = vNULL;
158 tree param_type_list = NULL, param_decl_list = NULL;
159 tree t, ref, return_type, fntype, fnname, fndecl;
162 vec<tree, va_gc> *args = NULL;
164 /* Do not factor out simple operations. */
165 t = skip_simple_constant_arithmetic (size);
166 if (TREE_CODE (t) == CALL_EXPR || self_referential_component_ref_p (t))
169 /* Collect the list of self-references in the expression. */
170 find_placeholder_in_expr (size, &self_refs);
171 gcc_assert (self_refs.length () > 0);
173 /* Obtain a private copy of the expression. */
175 if (walk_tree (&t, copy_self_referential_tree_r, NULL, NULL) != NULL_TREE)
179 /* Build the parameter and argument lists in parallel; also
180 substitute the former for the latter in the expression. */
181 vec_alloc (args, self_refs.length ());
182 FOR_EACH_VEC_ELT (self_refs, i, ref)
184 tree subst, param_name, param_type, param_decl;
188 /* We shouldn't have true variables here. */
189 gcc_assert (TREE_READONLY (ref));
192 /* This is the pattern built in ada/make_aligning_type. */
193 else if (TREE_CODE (ref) == ADDR_EXPR)
195 /* Default case: the component reference. */
197 subst = TREE_OPERAND (ref, 1);
199 sprintf (buf, "p%d", i);
200 param_name = get_identifier (buf);
201 param_type = TREE_TYPE (ref);
203 = build_decl (input_location, PARM_DECL, param_name, param_type);
204 DECL_ARG_TYPE (param_decl) = param_type;
205 DECL_ARTIFICIAL (param_decl) = 1;
206 TREE_READONLY (param_decl) = 1;
208 size = substitute_in_expr (size, subst, param_decl);
210 param_type_list = tree_cons (NULL_TREE, param_type, param_type_list);
211 param_decl_list = chainon (param_decl, param_decl_list);
212 args->quick_push (ref);
215 self_refs.release ();
217 /* Append 'void' to indicate that the number of parameters is fixed. */
218 param_type_list = tree_cons (NULL_TREE, void_type_node, param_type_list);
220 /* The 3 lists have been created in reverse order. */
221 param_type_list = nreverse (param_type_list);
222 param_decl_list = nreverse (param_decl_list);
224 /* Build the function type. */
225 return_type = TREE_TYPE (size);
226 fntype = build_function_type (return_type, param_type_list);
228 /* Build the function declaration. */
229 sprintf (buf, "SZ" HOST_WIDE_INT_PRINT_UNSIGNED, fnno++);
230 fnname = get_file_function_name (buf);
231 fndecl = build_decl (input_location, FUNCTION_DECL, fnname, fntype);
232 for (t = param_decl_list; t; t = DECL_CHAIN (t))
233 DECL_CONTEXT (t) = fndecl;
234 DECL_ARGUMENTS (fndecl) = param_decl_list;
236 = build_decl (input_location, RESULT_DECL, 0, return_type);
237 DECL_CONTEXT (DECL_RESULT (fndecl)) = fndecl;
239 /* The function has been created by the compiler and we don't
240 want to emit debug info for it. */
241 DECL_ARTIFICIAL (fndecl) = 1;
242 DECL_IGNORED_P (fndecl) = 1;
244 /* It is supposed to be "const" and never throw. */
245 TREE_READONLY (fndecl) = 1;
246 TREE_NOTHROW (fndecl) = 1;
248 /* We want it to be inlined when this is deemed profitable, as
249 well as discarded if every call has been integrated. */
250 DECL_DECLARED_INLINE_P (fndecl) = 1;
252 /* It is made up of a unique return statement. */
253 DECL_INITIAL (fndecl) = make_node (BLOCK);
254 BLOCK_SUPERCONTEXT (DECL_INITIAL (fndecl)) = fndecl;
255 t = build2 (MODIFY_EXPR, return_type, DECL_RESULT (fndecl), size);
256 DECL_SAVED_TREE (fndecl) = build1 (RETURN_EXPR, void_type_node, t);
257 TREE_STATIC (fndecl) = 1;
259 /* Put it onto the list of size functions. */
260 vec_safe_push (size_functions, fndecl);
262 /* Replace the original expression with a call to the size function. */
263 return build_call_expr_loc_vec (UNKNOWN_LOCATION, fndecl, args);
266 /* Take, queue and compile all the size functions. It is essential that
267 the size functions be gimplified at the very end of the compilation
268 in order to guarantee transparent handling of self-referential sizes.
269 Otherwise the GENERIC inliner would not be able to inline them back
270 at each of their call sites, thus creating artificial non-constant
271 size expressions which would trigger nasty problems later on. */
274 finalize_size_functions (void)
279 for (i = 0; size_functions && size_functions->iterate (i, &fndecl); i++)
281 allocate_struct_function (fndecl, false);
283 dump_function (TDI_original, fndecl);
285 /* As these functions are used to describe the layout of variable-length
286 structures, debug info generation needs their implementation. */
287 debug_hooks->size_function (fndecl);
288 gimplify_function_tree (fndecl);
289 cgraph_node::finalize_function (fndecl, false);
292 vec_free (size_functions);
295 /* Return a machine mode of class MCLASS with SIZE bits of precision,
296 if one exists. The mode may have padding bits as well the SIZE
297 value bits. If LIMIT is nonzero, disregard modes wider than
298 MAX_FIXED_MODE_SIZE. */
301 mode_for_size (poly_uint64 size, enum mode_class mclass, int limit)
306 if (limit && maybe_gt (size, (unsigned int) MAX_FIXED_MODE_SIZE))
307 return opt_machine_mode ();
309 /* Get the first mode which has this size, in the specified class. */
310 FOR_EACH_MODE_IN_CLASS (mode, mclass)
311 if (known_eq (GET_MODE_PRECISION (mode), size))
314 if (mclass == MODE_INT || mclass == MODE_PARTIAL_INT)
315 for (i = 0; i < NUM_INT_N_ENTS; i ++)
316 if (known_eq (int_n_data[i].bitsize, size)
317 && int_n_enabled_p[i])
318 return int_n_data[i].m;
320 return opt_machine_mode ();
323 /* Similar, except passed a tree node. */
326 mode_for_size_tree (const_tree size, enum mode_class mclass, int limit)
328 unsigned HOST_WIDE_INT uhwi;
331 if (!tree_fits_uhwi_p (size))
332 return opt_machine_mode ();
333 uhwi = tree_to_uhwi (size);
336 return opt_machine_mode ();
337 return mode_for_size (ui, mclass, limit);
340 /* Return the narrowest mode of class MCLASS that contains at least
341 SIZE bits. Abort if no such mode exists. */
344 smallest_mode_for_size (poly_uint64 size, enum mode_class mclass)
346 machine_mode mode = VOIDmode;
349 /* Get the first mode which has at least this size, in the
351 FOR_EACH_MODE_IN_CLASS (mode, mclass)
352 if (known_ge (GET_MODE_PRECISION (mode), size))
355 gcc_assert (mode != VOIDmode);
357 if (mclass == MODE_INT || mclass == MODE_PARTIAL_INT)
358 for (i = 0; i < NUM_INT_N_ENTS; i ++)
359 if (known_ge (int_n_data[i].bitsize, size)
360 && known_lt (int_n_data[i].bitsize, GET_MODE_PRECISION (mode))
361 && int_n_enabled_p[i])
362 mode = int_n_data[i].m;
367 /* Return an integer mode of exactly the same size as MODE, if one exists. */
370 int_mode_for_mode (machine_mode mode)
372 switch (GET_MODE_CLASS (mode))
375 case MODE_PARTIAL_INT:
376 return as_a <scalar_int_mode> (mode);
378 case MODE_COMPLEX_INT:
379 case MODE_COMPLEX_FLOAT:
381 case MODE_DECIMAL_FLOAT:
386 case MODE_VECTOR_BOOL:
387 case MODE_VECTOR_INT:
388 case MODE_VECTOR_FLOAT:
389 case MODE_VECTOR_FRACT:
390 case MODE_VECTOR_ACCUM:
391 case MODE_VECTOR_UFRACT:
392 case MODE_VECTOR_UACCUM:
393 case MODE_POINTER_BOUNDS:
394 return int_mode_for_size (GET_MODE_BITSIZE (mode), 0);
398 return opt_scalar_int_mode ();
408 /* Find a mode that can be used for efficient bitwise operations on MODE,
412 bitwise_mode_for_mode (machine_mode mode)
414 /* Quick exit if we already have a suitable mode. */
415 scalar_int_mode int_mode;
416 if (is_a <scalar_int_mode> (mode, &int_mode)
417 && GET_MODE_BITSIZE (int_mode) <= MAX_FIXED_MODE_SIZE)
420 /* Reuse the sanity checks from int_mode_for_mode. */
421 gcc_checking_assert ((int_mode_for_mode (mode), true));
423 poly_int64 bitsize = GET_MODE_BITSIZE (mode);
425 /* Try to replace complex modes with complex modes. In general we
426 expect both components to be processed independently, so we only
427 care whether there is a register for the inner mode. */
428 if (COMPLEX_MODE_P (mode))
430 machine_mode trial = mode;
431 if ((GET_MODE_CLASS (trial) == MODE_COMPLEX_INT
432 || mode_for_size (bitsize, MODE_COMPLEX_INT, false).exists (&trial))
433 && have_regs_of_mode[GET_MODE_INNER (trial)])
437 /* Try to replace vector modes with vector modes. Also try using vector
438 modes if an integer mode would be too big. */
439 if (VECTOR_MODE_P (mode)
440 || maybe_gt (bitsize, MAX_FIXED_MODE_SIZE))
442 machine_mode trial = mode;
443 if ((GET_MODE_CLASS (trial) == MODE_VECTOR_INT
444 || mode_for_size (bitsize, MODE_VECTOR_INT, 0).exists (&trial))
445 && have_regs_of_mode[trial]
446 && targetm.vector_mode_supported_p (trial))
450 /* Otherwise fall back on integers while honoring MAX_FIXED_MODE_SIZE. */
451 return mode_for_size (bitsize, MODE_INT, true);
454 /* Find a type that can be used for efficient bitwise operations on MODE.
455 Return null if no such mode exists. */
458 bitwise_type_for_mode (machine_mode mode)
460 if (!bitwise_mode_for_mode (mode).exists (&mode))
463 unsigned int inner_size = GET_MODE_UNIT_BITSIZE (mode);
464 tree inner_type = build_nonstandard_integer_type (inner_size, true);
466 if (VECTOR_MODE_P (mode))
467 return build_vector_type_for_mode (inner_type, mode);
469 if (COMPLEX_MODE_P (mode))
470 return build_complex_type (inner_type);
472 gcc_checking_assert (GET_MODE_INNER (mode) == mode);
476 /* Find a mode that is suitable for representing a vector with NUNITS
477 elements of mode INNERMODE, if one exists. The returned mode can be
478 either an integer mode or a vector mode. */
481 mode_for_vector (scalar_mode innermode, poly_uint64 nunits)
485 /* First, look for a supported vector type. */
486 if (SCALAR_FLOAT_MODE_P (innermode))
487 mode = MIN_MODE_VECTOR_FLOAT;
488 else if (SCALAR_FRACT_MODE_P (innermode))
489 mode = MIN_MODE_VECTOR_FRACT;
490 else if (SCALAR_UFRACT_MODE_P (innermode))
491 mode = MIN_MODE_VECTOR_UFRACT;
492 else if (SCALAR_ACCUM_MODE_P (innermode))
493 mode = MIN_MODE_VECTOR_ACCUM;
494 else if (SCALAR_UACCUM_MODE_P (innermode))
495 mode = MIN_MODE_VECTOR_UACCUM;
497 mode = MIN_MODE_VECTOR_INT;
499 /* Do not check vector_mode_supported_p here. We'll do that
500 later in vector_type_mode. */
501 FOR_EACH_MODE_FROM (mode, mode)
502 if (known_eq (GET_MODE_NUNITS (mode), nunits)
503 && GET_MODE_INNER (mode) == innermode)
506 /* For integers, try mapping it to a same-sized scalar mode. */
507 if (GET_MODE_CLASS (innermode) == MODE_INT)
509 poly_uint64 nbits = nunits * GET_MODE_BITSIZE (innermode);
510 if (int_mode_for_size (nbits, 0).exists (&mode)
511 && have_regs_of_mode[mode])
515 return opt_machine_mode ();
518 /* Return the mode for a vector that has NUNITS integer elements of
519 INT_BITS bits each, if such a mode exists. The mode can be either
520 an integer mode or a vector mode. */
523 mode_for_int_vector (unsigned int int_bits, poly_uint64 nunits)
525 scalar_int_mode int_mode;
526 machine_mode vec_mode;
527 if (int_mode_for_size (int_bits, 0).exists (&int_mode)
528 && mode_for_vector (int_mode, nunits).exists (&vec_mode))
530 return opt_machine_mode ();
533 /* Return the alignment of MODE. This will be bounded by 1 and
534 BIGGEST_ALIGNMENT. */
537 get_mode_alignment (machine_mode mode)
539 return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
542 /* Return the natural mode of an array, given that it is SIZE bytes in
543 total and has elements of type ELEM_TYPE. */
546 mode_for_array (tree elem_type, tree size)
549 poly_uint64 int_size, int_elem_size;
550 unsigned HOST_WIDE_INT num_elems;
553 /* One-element arrays get the component type's mode. */
554 elem_size = TYPE_SIZE (elem_type);
555 if (simple_cst_equal (size, elem_size))
556 return TYPE_MODE (elem_type);
559 if (poly_int_tree_p (size, &int_size)
560 && poly_int_tree_p (elem_size, &int_elem_size)
561 && maybe_ne (int_elem_size, 0U)
562 && constant_multiple_p (int_size, int_elem_size, &num_elems))
564 machine_mode elem_mode = TYPE_MODE (elem_type);
566 if (targetm.array_mode (elem_mode, num_elems).exists (&mode))
568 if (targetm.array_mode_supported_p (elem_mode, num_elems))
571 return mode_for_size_tree (size, MODE_INT, limit_p).else_blk ();
574 /* Subroutine of layout_decl: Force alignment required for the data type.
575 But if the decl itself wants greater alignment, don't override that. */
578 do_type_align (tree type, tree decl)
580 if (TYPE_ALIGN (type) > DECL_ALIGN (decl))
582 SET_DECL_ALIGN (decl, TYPE_ALIGN (type));
583 if (TREE_CODE (decl) == FIELD_DECL)
584 DECL_USER_ALIGN (decl) = TYPE_USER_ALIGN (type);
586 if (TYPE_WARN_IF_NOT_ALIGN (type) > DECL_WARN_IF_NOT_ALIGN (decl))
587 SET_DECL_WARN_IF_NOT_ALIGN (decl, TYPE_WARN_IF_NOT_ALIGN (type));
590 /* Set the size, mode and alignment of a ..._DECL node.
591 TYPE_DECL does need this for C++.
592 Note that LABEL_DECL and CONST_DECL nodes do not need this,
593 and FUNCTION_DECL nodes have them set up in a special (and simple) way.
594 Don't call layout_decl for them.
596 KNOWN_ALIGN is the amount of alignment we can assume this
597 decl has with no special effort. It is relevant only for FIELD_DECLs
598 and depends on the previous fields.
599 All that matters about KNOWN_ALIGN is which powers of 2 divide it.
600 If KNOWN_ALIGN is 0, it means, "as much alignment as you like":
601 the record will be aligned to suit. */
604 layout_decl (tree decl, unsigned int known_align)
606 tree type = TREE_TYPE (decl);
607 enum tree_code code = TREE_CODE (decl);
609 location_t loc = DECL_SOURCE_LOCATION (decl);
611 if (code == CONST_DECL)
614 gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL
615 || code == TYPE_DECL || code == FIELD_DECL);
617 rtl = DECL_RTL_IF_SET (decl);
619 if (type == error_mark_node)
620 type = void_type_node;
622 /* Usually the size and mode come from the data type without change,
623 however, the front-end may set the explicit width of the field, so its
624 size may not be the same as the size of its type. This happens with
625 bitfields, of course (an `int' bitfield may be only 2 bits, say), but it
626 also happens with other fields. For example, the C++ front-end creates
627 zero-sized fields corresponding to empty base classes, and depends on
628 layout_type setting DECL_FIELD_BITPOS correctly for the field. Set the
629 size in bytes from the size in bits. If we have already set the mode,
630 don't set it again since we can be called twice for FIELD_DECLs. */
632 DECL_UNSIGNED (decl) = TYPE_UNSIGNED (type);
633 if (DECL_MODE (decl) == VOIDmode)
634 SET_DECL_MODE (decl, TYPE_MODE (type));
636 if (DECL_SIZE (decl) == 0)
638 DECL_SIZE (decl) = TYPE_SIZE (type);
639 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
641 else if (DECL_SIZE_UNIT (decl) == 0)
642 DECL_SIZE_UNIT (decl)
643 = fold_convert_loc (loc, sizetype,
644 size_binop_loc (loc, CEIL_DIV_EXPR, DECL_SIZE (decl),
647 if (code != FIELD_DECL)
648 /* For non-fields, update the alignment from the type. */
649 do_type_align (type, decl);
651 /* For fields, it's a bit more complicated... */
653 bool old_user_align = DECL_USER_ALIGN (decl);
654 bool zero_bitfield = false;
655 bool packed_p = DECL_PACKED (decl);
658 if (DECL_BIT_FIELD (decl))
660 DECL_BIT_FIELD_TYPE (decl) = type;
662 /* A zero-length bit-field affects the alignment of the next
663 field. In essence such bit-fields are not influenced by
664 any packing due to #pragma pack or attribute packed. */
665 if (integer_zerop (DECL_SIZE (decl))
666 && ! targetm.ms_bitfield_layout_p (DECL_FIELD_CONTEXT (decl)))
668 zero_bitfield = true;
670 if (PCC_BITFIELD_TYPE_MATTERS)
671 do_type_align (type, decl);
674 #ifdef EMPTY_FIELD_BOUNDARY
675 if (EMPTY_FIELD_BOUNDARY > DECL_ALIGN (decl))
677 SET_DECL_ALIGN (decl, EMPTY_FIELD_BOUNDARY);
678 DECL_USER_ALIGN (decl) = 0;
684 /* See if we can use an ordinary integer mode for a bit-field.
685 Conditions are: a fixed size that is correct for another mode,
686 occupying a complete byte or bytes on proper boundary. */
687 if (TYPE_SIZE (type) != 0
688 && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
689 && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
692 if (mode_for_size_tree (DECL_SIZE (decl),
693 MODE_INT, 1).exists (&xmode))
695 unsigned int xalign = GET_MODE_ALIGNMENT (xmode);
696 if (!(xalign > BITS_PER_UNIT && DECL_PACKED (decl))
697 && (known_align == 0 || known_align >= xalign))
699 SET_DECL_ALIGN (decl, MAX (xalign, DECL_ALIGN (decl)));
700 SET_DECL_MODE (decl, xmode);
701 DECL_BIT_FIELD (decl) = 0;
706 /* Turn off DECL_BIT_FIELD if we won't need it set. */
707 if (TYPE_MODE (type) == BLKmode && DECL_MODE (decl) == BLKmode
708 && known_align >= TYPE_ALIGN (type)
709 && DECL_ALIGN (decl) >= TYPE_ALIGN (type))
710 DECL_BIT_FIELD (decl) = 0;
712 else if (packed_p && DECL_USER_ALIGN (decl))
713 /* Don't touch DECL_ALIGN. For other packed fields, go ahead and
714 round up; we'll reduce it again below. We want packing to
715 supersede USER_ALIGN inherited from the type, but defer to
716 alignment explicitly specified on the field decl. */;
718 do_type_align (type, decl);
720 /* If the field is packed and not explicitly aligned, give it the
721 minimum alignment. Note that do_type_align may set
722 DECL_USER_ALIGN, so we need to check old_user_align instead. */
725 SET_DECL_ALIGN (decl, MIN (DECL_ALIGN (decl), BITS_PER_UNIT));
727 if (! packed_p && ! DECL_USER_ALIGN (decl))
729 /* Some targets (i.e. i386, VMS) limit struct field alignment
730 to a lower boundary than alignment of variables unless
731 it was overridden by attribute aligned. */
732 #ifdef BIGGEST_FIELD_ALIGNMENT
733 SET_DECL_ALIGN (decl, MIN (DECL_ALIGN (decl),
734 (unsigned) BIGGEST_FIELD_ALIGNMENT));
736 #ifdef ADJUST_FIELD_ALIGN
737 SET_DECL_ALIGN (decl, ADJUST_FIELD_ALIGN (decl, TREE_TYPE (decl),
743 mfa = initial_max_fld_align * BITS_PER_UNIT;
745 mfa = maximum_field_alignment;
746 /* Should this be controlled by DECL_USER_ALIGN, too? */
748 SET_DECL_ALIGN (decl, MIN (DECL_ALIGN (decl), mfa));
751 /* Evaluate nonconstant size only once, either now or as soon as safe. */
752 if (DECL_SIZE (decl) != 0 && TREE_CODE (DECL_SIZE (decl)) != INTEGER_CST)
753 DECL_SIZE (decl) = variable_size (DECL_SIZE (decl));
754 if (DECL_SIZE_UNIT (decl) != 0
755 && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST)
756 DECL_SIZE_UNIT (decl) = variable_size (DECL_SIZE_UNIT (decl));
758 /* If requested, warn about definitions of large data objects. */
760 && (code == VAR_DECL || code == PARM_DECL)
761 && ! DECL_EXTERNAL (decl))
763 tree size = DECL_SIZE_UNIT (decl);
765 if (size != 0 && TREE_CODE (size) == INTEGER_CST
766 && compare_tree_int (size, larger_than_size) > 0)
768 int size_as_int = TREE_INT_CST_LOW (size);
770 if (compare_tree_int (size, size_as_int) == 0)
771 warning (OPT_Wlarger_than_, "size of %q+D is %d bytes", decl, size_as_int);
773 warning (OPT_Wlarger_than_, "size of %q+D is larger than %wd bytes",
774 decl, larger_than_size);
778 /* If the RTL was already set, update its mode and mem attributes. */
781 PUT_MODE (rtl, DECL_MODE (decl));
782 SET_DECL_RTL (decl, 0);
784 set_mem_attributes (rtl, decl, 1);
785 SET_DECL_RTL (decl, rtl);
789 /* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the
790 results of a previous call to layout_decl and calls it again. */
793 relayout_decl (tree decl)
795 DECL_SIZE (decl) = DECL_SIZE_UNIT (decl) = 0;
796 SET_DECL_MODE (decl, VOIDmode);
797 if (!DECL_USER_ALIGN (decl))
798 SET_DECL_ALIGN (decl, 0);
799 if (DECL_RTL_SET_P (decl))
800 SET_DECL_RTL (decl, 0);
802 layout_decl (decl, 0);
805 /* Begin laying out type T, which may be a RECORD_TYPE, UNION_TYPE, or
806 QUAL_UNION_TYPE. Return a pointer to a struct record_layout_info which
807 is to be passed to all other layout functions for this record. It is the
808 responsibility of the caller to call `free' for the storage returned.
809 Note that garbage collection is not permitted until we finish laying
813 start_record_layout (tree t)
815 record_layout_info rli = XNEW (struct record_layout_info_s);
819 /* If the type has a minimum specified alignment (via an attribute
820 declaration, for example) use it -- otherwise, start with a
821 one-byte alignment. */
822 rli->record_align = MAX (BITS_PER_UNIT, TYPE_ALIGN (t));
823 rli->unpacked_align = rli->record_align;
824 rli->offset_align = MAX (rli->record_align, BIGGEST_ALIGNMENT);
826 #ifdef STRUCTURE_SIZE_BOUNDARY
827 /* Packed structures don't need to have minimum size. */
828 if (! TYPE_PACKED (t))
832 /* #pragma pack overrides STRUCTURE_SIZE_BOUNDARY. */
833 tmp = (unsigned) STRUCTURE_SIZE_BOUNDARY;
834 if (maximum_field_alignment != 0)
835 tmp = MIN (tmp, maximum_field_alignment);
836 rli->record_align = MAX (rli->record_align, tmp);
840 rli->offset = size_zero_node;
841 rli->bitpos = bitsize_zero_node;
843 rli->pending_statics = 0;
844 rli->packed_maybe_necessary = 0;
845 rli->remaining_in_alignment = 0;
850 /* Fold sizetype value X to bitsizetype, given that X represents a type
854 bits_from_bytes (tree x)
856 if (POLY_INT_CST_P (x))
857 /* The runtime calculation isn't allowed to overflow sizetype;
858 increasing the runtime values must always increase the size
859 or offset of the object. This means that the object imposes
860 a maximum value on the runtime parameters, but we don't record
862 return build_poly_int_cst
864 poly_wide_int::from (poly_int_cst_value (x),
865 TYPE_PRECISION (bitsizetype),
866 TYPE_SIGN (TREE_TYPE (x))));
867 x = fold_convert (bitsizetype, x);
868 gcc_checking_assert (x);
872 /* Return the combined bit position for the byte offset OFFSET and the
875 These functions operate on byte and bit positions present in FIELD_DECLs
876 and assume that these expressions result in no (intermediate) overflow.
877 This assumption is necessary to fold the expressions as much as possible,
878 so as to avoid creating artificially variable-sized types in languages
879 supporting variable-sized types like Ada. */
882 bit_from_pos (tree offset, tree bitpos)
884 return size_binop (PLUS_EXPR, bitpos,
885 size_binop (MULT_EXPR, bits_from_bytes (offset),
889 /* Return the combined truncated byte position for the byte offset OFFSET and
890 the bit position BITPOS. */
893 byte_from_pos (tree offset, tree bitpos)
896 if (TREE_CODE (bitpos) == MULT_EXPR
897 && tree_int_cst_equal (TREE_OPERAND (bitpos, 1), bitsize_unit_node))
898 bytepos = TREE_OPERAND (bitpos, 0);
900 bytepos = size_binop (TRUNC_DIV_EXPR, bitpos, bitsize_unit_node);
901 return size_binop (PLUS_EXPR, offset, fold_convert (sizetype, bytepos));
904 /* Split the bit position POS into a byte offset *POFFSET and a bit
905 position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
908 pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
911 tree toff_align = bitsize_int (off_align);
912 if (TREE_CODE (pos) == MULT_EXPR
913 && tree_int_cst_equal (TREE_OPERAND (pos, 1), toff_align))
915 *poffset = size_binop (MULT_EXPR,
916 fold_convert (sizetype, TREE_OPERAND (pos, 0)),
917 size_int (off_align / BITS_PER_UNIT));
918 *pbitpos = bitsize_zero_node;
922 *poffset = size_binop (MULT_EXPR,
923 fold_convert (sizetype,
924 size_binop (FLOOR_DIV_EXPR, pos,
926 size_int (off_align / BITS_PER_UNIT));
927 *pbitpos = size_binop (FLOOR_MOD_EXPR, pos, toff_align);
931 /* Given a pointer to bit and byte offsets and an offset alignment,
932 normalize the offsets so they are within the alignment. */
935 normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
937 /* If the bit position is now larger than it should be, adjust it
939 if (compare_tree_int (*pbitpos, off_align) >= 0)
942 pos_from_bit (&offset, &bitpos, off_align, *pbitpos);
943 *poffset = size_binop (PLUS_EXPR, *poffset, offset);
948 /* Print debugging information about the information in RLI. */
951 debug_rli (record_layout_info rli)
953 print_node_brief (stderr, "type", rli->t, 0);
954 print_node_brief (stderr, "\noffset", rli->offset, 0);
955 print_node_brief (stderr, " bitpos", rli->bitpos, 0);
957 fprintf (stderr, "\naligns: rec = %u, unpack = %u, off = %u\n",
958 rli->record_align, rli->unpacked_align,
961 /* The ms_struct code is the only that uses this. */
962 if (targetm.ms_bitfield_layout_p (rli->t))
963 fprintf (stderr, "remaining in alignment = %u\n", rli->remaining_in_alignment);
965 if (rli->packed_maybe_necessary)
966 fprintf (stderr, "packed may be necessary\n");
968 if (!vec_safe_is_empty (rli->pending_statics))
970 fprintf (stderr, "pending statics:\n");
971 debug (rli->pending_statics);
975 /* Given an RLI with a possibly-incremented BITPOS, adjust OFFSET and
976 BITPOS if necessary to keep BITPOS below OFFSET_ALIGN. */
979 normalize_rli (record_layout_info rli)
981 normalize_offset (&rli->offset, &rli->bitpos, rli->offset_align);
984 /* Returns the size in bytes allocated so far. */
987 rli_size_unit_so_far (record_layout_info rli)
989 return byte_from_pos (rli->offset, rli->bitpos);
992 /* Returns the size in bits allocated so far. */
995 rli_size_so_far (record_layout_info rli)
997 return bit_from_pos (rli->offset, rli->bitpos);
1000 /* FIELD is about to be added to RLI->T. The alignment (in bits) of
1001 the next available location within the record is given by KNOWN_ALIGN.
1002 Update the variable alignment fields in RLI, and return the alignment
1003 to give the FIELD. */
1006 update_alignment_for_field (record_layout_info rli, tree field,
1007 unsigned int known_align)
1009 /* The alignment required for FIELD. */
1010 unsigned int desired_align;
1011 /* The type of this field. */
1012 tree type = TREE_TYPE (field);
1013 /* True if the field was explicitly aligned by the user. */
1017 /* Do not attempt to align an ERROR_MARK node */
1018 if (TREE_CODE (type) == ERROR_MARK)
1021 /* Lay out the field so we know what alignment it needs. */
1022 layout_decl (field, known_align);
1023 desired_align = DECL_ALIGN (field);
1024 user_align = DECL_USER_ALIGN (field);
1026 is_bitfield = (type != error_mark_node
1027 && DECL_BIT_FIELD_TYPE (field)
1028 && ! integer_zerop (TYPE_SIZE (type)));
1030 /* Record must have at least as much alignment as any field.
1031 Otherwise, the alignment of the field within the record is
1033 if (targetm.ms_bitfield_layout_p (rli->t))
1035 /* Here, the alignment of the underlying type of a bitfield can
1036 affect the alignment of a record; even a zero-sized field
1037 can do this. The alignment should be to the alignment of
1038 the type, except that for zero-size bitfields this only
1039 applies if there was an immediately prior, nonzero-size
1040 bitfield. (That's the way it is, experimentally.) */
1042 || ((DECL_SIZE (field) == NULL_TREE
1043 || !integer_zerop (DECL_SIZE (field)))
1044 ? !DECL_PACKED (field)
1046 && DECL_BIT_FIELD_TYPE (rli->prev_field)
1047 && ! integer_zerop (DECL_SIZE (rli->prev_field)))))
1049 unsigned int type_align = TYPE_ALIGN (type);
1050 if (!is_bitfield && DECL_PACKED (field))
1051 type_align = desired_align;
1053 type_align = MAX (type_align, desired_align);
1054 if (maximum_field_alignment != 0)
1055 type_align = MIN (type_align, maximum_field_alignment);
1056 rli->record_align = MAX (rli->record_align, type_align);
1057 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
1060 else if (is_bitfield && PCC_BITFIELD_TYPE_MATTERS)
1062 /* Named bit-fields cause the entire structure to have the
1063 alignment implied by their type. Some targets also apply the same
1064 rules to unnamed bitfields. */
1065 if (DECL_NAME (field) != 0
1066 || targetm.align_anon_bitfield ())
1068 unsigned int type_align = TYPE_ALIGN (type);
1070 #ifdef ADJUST_FIELD_ALIGN
1071 if (! TYPE_USER_ALIGN (type))
1072 type_align = ADJUST_FIELD_ALIGN (field, type, type_align);
1075 /* Targets might chose to handle unnamed and hence possibly
1076 zero-width bitfield. Those are not influenced by #pragmas
1077 or packed attributes. */
1078 if (integer_zerop (DECL_SIZE (field)))
1080 if (initial_max_fld_align)
1081 type_align = MIN (type_align,
1082 initial_max_fld_align * BITS_PER_UNIT);
1084 else if (maximum_field_alignment != 0)
1085 type_align = MIN (type_align, maximum_field_alignment);
1086 else if (DECL_PACKED (field))
1087 type_align = MIN (type_align, BITS_PER_UNIT);
1089 /* The alignment of the record is increased to the maximum
1090 of the current alignment, the alignment indicated on the
1091 field (i.e., the alignment specified by an __aligned__
1092 attribute), and the alignment indicated by the type of
1094 rli->record_align = MAX (rli->record_align, desired_align);
1095 rli->record_align = MAX (rli->record_align, type_align);
1098 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
1099 user_align |= TYPE_USER_ALIGN (type);
1104 rli->record_align = MAX (rli->record_align, desired_align);
1105 rli->unpacked_align = MAX (rli->unpacked_align, TYPE_ALIGN (type));
1108 TYPE_USER_ALIGN (rli->t) |= user_align;
1110 return desired_align;
1113 /* Issue a warning if the record alignment, RECORD_ALIGN, is less than
1114 the field alignment of FIELD or FIELD isn't aligned. */
1117 handle_warn_if_not_align (tree field, unsigned int record_align)
1119 tree type = TREE_TYPE (field);
1121 if (type == error_mark_node)
1124 unsigned int warn_if_not_align = 0;
1128 if (warn_if_not_aligned)
1130 warn_if_not_align = DECL_WARN_IF_NOT_ALIGN (field);
1131 if (!warn_if_not_align)
1132 warn_if_not_align = TYPE_WARN_IF_NOT_ALIGN (type);
1133 if (warn_if_not_align)
1134 opt_w = OPT_Wif_not_aligned;
1137 if (!warn_if_not_align
1138 && warn_packed_not_aligned
1139 && lookup_attribute ("aligned", TYPE_ATTRIBUTES (type)))
1141 warn_if_not_align = TYPE_ALIGN (type);
1142 opt_w = OPT_Wpacked_not_aligned;
1145 if (!warn_if_not_align)
1148 tree context = DECL_CONTEXT (field);
1150 warn_if_not_align /= BITS_PER_UNIT;
1151 record_align /= BITS_PER_UNIT;
1152 if ((record_align % warn_if_not_align) != 0)
1153 warning (opt_w, "alignment %u of %qT is less than %u",
1154 record_align, context, warn_if_not_align);
1156 tree off = byte_position (field);
1157 if (!multiple_of_p (TREE_TYPE (off), off, size_int (warn_if_not_align)))
1159 if (TREE_CODE (off) == INTEGER_CST)
1160 warning (opt_w, "%q+D offset %E in %qT isn%'t aligned to %u",
1161 field, off, context, warn_if_not_align);
1163 warning (opt_w, "%q+D offset %E in %qT may not be aligned to %u",
1164 field, off, context, warn_if_not_align);
1168 /* Called from place_field to handle unions. */
1171 place_union_field (record_layout_info rli, tree field)
1173 update_alignment_for_field (rli, field, /*known_align=*/0);
1175 DECL_FIELD_OFFSET (field) = size_zero_node;
1176 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
1177 SET_DECL_OFFSET_ALIGN (field, BIGGEST_ALIGNMENT);
1178 handle_warn_if_not_align (field, rli->record_align);
1180 /* If this is an ERROR_MARK return *after* having set the
1181 field at the start of the union. This helps when parsing
1183 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK)
1186 if (AGGREGATE_TYPE_P (TREE_TYPE (field))
1187 && TYPE_TYPELESS_STORAGE (TREE_TYPE (field)))
1188 TYPE_TYPELESS_STORAGE (rli->t) = 1;
1190 /* We assume the union's size will be a multiple of a byte so we don't
1191 bother with BITPOS. */
1192 if (TREE_CODE (rli->t) == UNION_TYPE)
1193 rli->offset = size_binop (MAX_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1194 else if (TREE_CODE (rli->t) == QUAL_UNION_TYPE)
1195 rli->offset = fold_build3 (COND_EXPR, sizetype, DECL_QUALIFIER (field),
1196 DECL_SIZE_UNIT (field), rli->offset);
1199 /* A bitfield of SIZE with a required access alignment of ALIGN is allocated
1200 at BYTE_OFFSET / BIT_OFFSET. Return nonzero if the field would span more
1201 units of alignment than the underlying TYPE. */
1203 excess_unit_span (HOST_WIDE_INT byte_offset, HOST_WIDE_INT bit_offset,
1204 HOST_WIDE_INT size, HOST_WIDE_INT align, tree type)
1206 /* Note that the calculation of OFFSET might overflow; we calculate it so
1207 that we still get the right result as long as ALIGN is a power of two. */
1208 unsigned HOST_WIDE_INT offset = byte_offset * BITS_PER_UNIT + bit_offset;
1210 offset = offset % align;
1211 return ((offset + size + align - 1) / align
1212 > tree_to_uhwi (TYPE_SIZE (type)) / align);
1215 /* RLI contains information about the layout of a RECORD_TYPE. FIELD
1216 is a FIELD_DECL to be added after those fields already present in
1217 T. (FIELD is not actually added to the TYPE_FIELDS list here;
1218 callers that desire that behavior must manually perform that step.) */
1221 place_field (record_layout_info rli, tree field)
1223 /* The alignment required for FIELD. */
1224 unsigned int desired_align;
1225 /* The alignment FIELD would have if we just dropped it into the
1226 record as it presently stands. */
1227 unsigned int known_align;
1228 unsigned int actual_align;
1229 /* The type of this field. */
1230 tree type = TREE_TYPE (field);
1232 gcc_assert (TREE_CODE (field) != ERROR_MARK);
1234 /* If FIELD is static, then treat it like a separate variable, not
1235 really like a structure field. If it is a FUNCTION_DECL, it's a
1236 method. In both cases, all we do is lay out the decl, and we do
1237 it *after* the record is laid out. */
1240 vec_safe_push (rli->pending_statics, field);
1244 /* Enumerators and enum types which are local to this class need not
1245 be laid out. Likewise for initialized constant fields. */
1246 else if (TREE_CODE (field) != FIELD_DECL)
1249 /* Unions are laid out very differently than records, so split
1250 that code off to another function. */
1251 else if (TREE_CODE (rli->t) != RECORD_TYPE)
1253 place_union_field (rli, field);
1257 else if (TREE_CODE (type) == ERROR_MARK)
1259 /* Place this field at the current allocation position, so we
1260 maintain monotonicity. */
1261 DECL_FIELD_OFFSET (field) = rli->offset;
1262 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1263 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1264 handle_warn_if_not_align (field, rli->record_align);
1268 if (AGGREGATE_TYPE_P (type)
1269 && TYPE_TYPELESS_STORAGE (type))
1270 TYPE_TYPELESS_STORAGE (rli->t) = 1;
1272 /* Work out the known alignment so far. Note that A & (-A) is the
1273 value of the least-significant bit in A that is one. */
1274 if (! integer_zerop (rli->bitpos))
1275 known_align = least_bit_hwi (tree_to_uhwi (rli->bitpos));
1276 else if (integer_zerop (rli->offset))
1278 else if (tree_fits_uhwi_p (rli->offset))
1279 known_align = (BITS_PER_UNIT
1280 * least_bit_hwi (tree_to_uhwi (rli->offset)));
1282 known_align = rli->offset_align;
1284 desired_align = update_alignment_for_field (rli, field, known_align);
1285 if (known_align == 0)
1286 known_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1288 if (warn_packed && DECL_PACKED (field))
1290 if (known_align >= TYPE_ALIGN (type))
1292 if (TYPE_ALIGN (type) > desired_align)
1294 if (STRICT_ALIGNMENT)
1295 warning (OPT_Wattributes, "packed attribute causes "
1296 "inefficient alignment for %q+D", field);
1297 /* Don't warn if DECL_PACKED was set by the type. */
1298 else if (!TYPE_PACKED (rli->t))
1299 warning (OPT_Wattributes, "packed attribute is "
1300 "unnecessary for %q+D", field);
1304 rli->packed_maybe_necessary = 1;
1307 /* Does this field automatically have alignment it needs by virtue
1308 of the fields that precede it and the record's own alignment? */
1309 if (known_align < desired_align
1310 && (! targetm.ms_bitfield_layout_p (rli->t)
1311 || rli->prev_field == NULL))
1313 /* No, we need to skip space before this field.
1314 Bump the cumulative size to multiple of field alignment. */
1316 if (!targetm.ms_bitfield_layout_p (rli->t)
1317 && DECL_SOURCE_LOCATION (field) != BUILTINS_LOCATION)
1318 warning (OPT_Wpadded, "padding struct to align %q+D", field);
1320 /* If the alignment is still within offset_align, just align
1321 the bit position. */
1322 if (desired_align < rli->offset_align)
1323 rli->bitpos = round_up (rli->bitpos, desired_align);
1326 /* First adjust OFFSET by the partial bits, then align. */
1328 = size_binop (PLUS_EXPR, rli->offset,
1329 fold_convert (sizetype,
1330 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1331 bitsize_unit_node)));
1332 rli->bitpos = bitsize_zero_node;
1334 rli->offset = round_up (rli->offset, desired_align / BITS_PER_UNIT);
1337 if (! TREE_CONSTANT (rli->offset))
1338 rli->offset_align = desired_align;
1341 /* Handle compatibility with PCC. Note that if the record has any
1342 variable-sized fields, we need not worry about compatibility. */
1343 if (PCC_BITFIELD_TYPE_MATTERS
1344 && ! targetm.ms_bitfield_layout_p (rli->t)
1345 && TREE_CODE (field) == FIELD_DECL
1346 && type != error_mark_node
1347 && DECL_BIT_FIELD (field)
1348 && (! DECL_PACKED (field)
1349 /* Enter for these packed fields only to issue a warning. */
1350 || TYPE_ALIGN (type) <= BITS_PER_UNIT)
1351 && maximum_field_alignment == 0
1352 && ! integer_zerop (DECL_SIZE (field))
1353 && tree_fits_uhwi_p (DECL_SIZE (field))
1354 && tree_fits_uhwi_p (rli->offset)
1355 && tree_fits_uhwi_p (TYPE_SIZE (type)))
1357 unsigned int type_align = TYPE_ALIGN (type);
1358 tree dsize = DECL_SIZE (field);
1359 HOST_WIDE_INT field_size = tree_to_uhwi (dsize);
1360 HOST_WIDE_INT offset = tree_to_uhwi (rli->offset);
1361 HOST_WIDE_INT bit_offset = tree_to_shwi (rli->bitpos);
1363 #ifdef ADJUST_FIELD_ALIGN
1364 if (! TYPE_USER_ALIGN (type))
1365 type_align = ADJUST_FIELD_ALIGN (field, type, type_align);
1368 /* A bit field may not span more units of alignment of its type
1369 than its type itself. Advance to next boundary if necessary. */
1370 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1372 if (DECL_PACKED (field))
1374 if (warn_packed_bitfield_compat == 1)
1377 "offset of packed bit-field %qD has changed in GCC 4.4",
1381 rli->bitpos = round_up (rli->bitpos, type_align);
1384 if (! DECL_PACKED (field))
1385 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1387 SET_TYPE_WARN_IF_NOT_ALIGN (rli->t,
1388 TYPE_WARN_IF_NOT_ALIGN (type));
1391 #ifdef BITFIELD_NBYTES_LIMITED
1392 if (BITFIELD_NBYTES_LIMITED
1393 && ! targetm.ms_bitfield_layout_p (rli->t)
1394 && TREE_CODE (field) == FIELD_DECL
1395 && type != error_mark_node
1396 && DECL_BIT_FIELD_TYPE (field)
1397 && ! DECL_PACKED (field)
1398 && ! integer_zerop (DECL_SIZE (field))
1399 && tree_fits_uhwi_p (DECL_SIZE (field))
1400 && tree_fits_uhwi_p (rli->offset)
1401 && tree_fits_uhwi_p (TYPE_SIZE (type)))
1403 unsigned int type_align = TYPE_ALIGN (type);
1404 tree dsize = DECL_SIZE (field);
1405 HOST_WIDE_INT field_size = tree_to_uhwi (dsize);
1406 HOST_WIDE_INT offset = tree_to_uhwi (rli->offset);
1407 HOST_WIDE_INT bit_offset = tree_to_shwi (rli->bitpos);
1409 #ifdef ADJUST_FIELD_ALIGN
1410 if (! TYPE_USER_ALIGN (type))
1411 type_align = ADJUST_FIELD_ALIGN (field, type, type_align);
1414 if (maximum_field_alignment != 0)
1415 type_align = MIN (type_align, maximum_field_alignment);
1416 /* ??? This test is opposite the test in the containing if
1417 statement, so this code is unreachable currently. */
1418 else if (DECL_PACKED (field))
1419 type_align = MIN (type_align, BITS_PER_UNIT);
1421 /* A bit field may not span the unit of alignment of its type.
1422 Advance to next boundary if necessary. */
1423 if (excess_unit_span (offset, bit_offset, field_size, type_align, type))
1424 rli->bitpos = round_up (rli->bitpos, type_align);
1426 TYPE_USER_ALIGN (rli->t) |= TYPE_USER_ALIGN (type);
1427 SET_TYPE_WARN_IF_NOT_ALIGN (rli->t,
1428 TYPE_WARN_IF_NOT_ALIGN (type));
1432 /* See the docs for TARGET_MS_BITFIELD_LAYOUT_P for details.
1434 When a bit field is inserted into a packed record, the whole
1435 size of the underlying type is used by one or more same-size
1436 adjacent bitfields. (That is, if its long:3, 32 bits is
1437 used in the record, and any additional adjacent long bitfields are
1438 packed into the same chunk of 32 bits. However, if the size
1439 changes, a new field of that size is allocated.) In an unpacked
1440 record, this is the same as using alignment, but not equivalent
1443 Note: for compatibility, we use the type size, not the type alignment
1444 to determine alignment, since that matches the documentation */
1446 if (targetm.ms_bitfield_layout_p (rli->t))
1448 tree prev_saved = rli->prev_field;
1449 tree prev_type = prev_saved ? DECL_BIT_FIELD_TYPE (prev_saved) : NULL;
1451 /* This is a bitfield if it exists. */
1452 if (rli->prev_field)
1454 bool realign_p = known_align < desired_align;
1456 /* If both are bitfields, nonzero, and the same size, this is
1457 the middle of a run. Zero declared size fields are special
1458 and handled as "end of run". (Note: it's nonzero declared
1459 size, but equal type sizes!) (Since we know that both
1460 the current and previous fields are bitfields by the
1461 time we check it, DECL_SIZE must be present for both.) */
1462 if (DECL_BIT_FIELD_TYPE (field)
1463 && !integer_zerop (DECL_SIZE (field))
1464 && !integer_zerop (DECL_SIZE (rli->prev_field))
1465 && tree_fits_shwi_p (DECL_SIZE (rli->prev_field))
1466 && tree_fits_uhwi_p (TYPE_SIZE (type))
1467 && simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type)))
1469 /* We're in the middle of a run of equal type size fields; make
1470 sure we realign if we run out of bits. (Not decl size,
1472 HOST_WIDE_INT bitsize = tree_to_uhwi (DECL_SIZE (field));
1474 if (rli->remaining_in_alignment < bitsize)
1476 HOST_WIDE_INT typesize = tree_to_uhwi (TYPE_SIZE (type));
1478 /* out of bits; bump up to next 'word'. */
1480 = size_binop (PLUS_EXPR, rli->bitpos,
1481 bitsize_int (rli->remaining_in_alignment));
1482 rli->prev_field = field;
1483 if (typesize < bitsize)
1484 rli->remaining_in_alignment = 0;
1486 rli->remaining_in_alignment = typesize - bitsize;
1490 rli->remaining_in_alignment -= bitsize;
1496 /* End of a run: if leaving a run of bitfields of the same type
1497 size, we have to "use up" the rest of the bits of the type
1500 Compute the new position as the sum of the size for the prior
1501 type and where we first started working on that type.
1502 Note: since the beginning of the field was aligned then
1503 of course the end will be too. No round needed. */
1505 if (!integer_zerop (DECL_SIZE (rli->prev_field)))
1508 = size_binop (PLUS_EXPR, rli->bitpos,
1509 bitsize_int (rli->remaining_in_alignment));
1512 /* We "use up" size zero fields; the code below should behave
1513 as if the prior field was not a bitfield. */
1516 /* Cause a new bitfield to be captured, either this time (if
1517 currently a bitfield) or next time we see one. */
1518 if (!DECL_BIT_FIELD_TYPE (field)
1519 || integer_zerop (DECL_SIZE (field)))
1520 rli->prev_field = NULL;
1523 /* Does this field automatically have alignment it needs by virtue
1524 of the fields that precede it and the record's own alignment? */
1527 /* If the alignment is still within offset_align, just align
1528 the bit position. */
1529 if (desired_align < rli->offset_align)
1530 rli->bitpos = round_up (rli->bitpos, desired_align);
1533 /* First adjust OFFSET by the partial bits, then align. */
1534 tree d = size_binop (CEIL_DIV_EXPR, rli->bitpos,
1536 rli->offset = size_binop (PLUS_EXPR, rli->offset,
1537 fold_convert (sizetype, d));
1538 rli->bitpos = bitsize_zero_node;
1540 rli->offset = round_up (rli->offset,
1541 desired_align / BITS_PER_UNIT);
1544 if (! TREE_CONSTANT (rli->offset))
1545 rli->offset_align = desired_align;
1548 normalize_rli (rli);
1551 /* If we're starting a new run of same type size bitfields
1552 (or a run of non-bitfields), set up the "first of the run"
1555 That is, if the current field is not a bitfield, or if there
1556 was a prior bitfield the type sizes differ, or if there wasn't
1557 a prior bitfield the size of the current field is nonzero.
1559 Note: we must be sure to test ONLY the type size if there was
1560 a prior bitfield and ONLY for the current field being zero if
1563 if (!DECL_BIT_FIELD_TYPE (field)
1564 || (prev_saved != NULL
1565 ? !simple_cst_equal (TYPE_SIZE (type), TYPE_SIZE (prev_type))
1566 : !integer_zerop (DECL_SIZE (field))))
1568 /* Never smaller than a byte for compatibility. */
1569 unsigned int type_align = BITS_PER_UNIT;
1571 /* (When not a bitfield), we could be seeing a flex array (with
1572 no DECL_SIZE). Since we won't be using remaining_in_alignment
1573 until we see a bitfield (and come by here again) we just skip
1575 if (DECL_SIZE (field) != NULL
1576 && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (field)))
1577 && tree_fits_uhwi_p (DECL_SIZE (field)))
1579 unsigned HOST_WIDE_INT bitsize
1580 = tree_to_uhwi (DECL_SIZE (field));
1581 unsigned HOST_WIDE_INT typesize
1582 = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (field)));
1584 if (typesize < bitsize)
1585 rli->remaining_in_alignment = 0;
1587 rli->remaining_in_alignment = typesize - bitsize;
1590 /* Now align (conventionally) for the new type. */
1591 if (! DECL_PACKED (field))
1592 type_align = TYPE_ALIGN (TREE_TYPE (field));
1594 if (maximum_field_alignment != 0)
1595 type_align = MIN (type_align, maximum_field_alignment);
1597 rli->bitpos = round_up (rli->bitpos, type_align);
1599 /* If we really aligned, don't allow subsequent bitfields
1601 rli->prev_field = NULL;
1605 /* Offset so far becomes the position of this field after normalizing. */
1606 normalize_rli (rli);
1607 DECL_FIELD_OFFSET (field) = rli->offset;
1608 DECL_FIELD_BIT_OFFSET (field) = rli->bitpos;
1609 SET_DECL_OFFSET_ALIGN (field, rli->offset_align);
1610 handle_warn_if_not_align (field, rli->record_align);
1612 /* Evaluate nonconstant offsets only once, either now or as soon as safe. */
1613 if (TREE_CODE (DECL_FIELD_OFFSET (field)) != INTEGER_CST)
1614 DECL_FIELD_OFFSET (field) = variable_size (DECL_FIELD_OFFSET (field));
1616 /* If this field ended up more aligned than we thought it would be (we
1617 approximate this by seeing if its position changed), lay out the field
1618 again; perhaps we can use an integral mode for it now. */
1619 if (! integer_zerop (DECL_FIELD_BIT_OFFSET (field)))
1620 actual_align = least_bit_hwi (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field)));
1621 else if (integer_zerop (DECL_FIELD_OFFSET (field)))
1622 actual_align = MAX (BIGGEST_ALIGNMENT, rli->record_align);
1623 else if (tree_fits_uhwi_p (DECL_FIELD_OFFSET (field)))
1624 actual_align = (BITS_PER_UNIT
1625 * least_bit_hwi (tree_to_uhwi (DECL_FIELD_OFFSET (field))));
1627 actual_align = DECL_OFFSET_ALIGN (field);
1628 /* ACTUAL_ALIGN is still the actual alignment *within the record* .
1629 store / extract bit field operations will check the alignment of the
1630 record against the mode of bit fields. */
1632 if (known_align != actual_align)
1633 layout_decl (field, actual_align);
1635 if (rli->prev_field == NULL && DECL_BIT_FIELD_TYPE (field))
1636 rli->prev_field = field;
1638 /* Now add size of this field to the size of the record. If the size is
1639 not constant, treat the field as being a multiple of bytes and just
1640 adjust the offset, resetting the bit position. Otherwise, apportion the
1641 size amongst the bit position and offset. First handle the case of an
1642 unspecified size, which can happen when we have an invalid nested struct
1643 definition, such as struct j { struct j { int i; } }. The error message
1644 is printed in finish_struct. */
1645 if (DECL_SIZE (field) == 0)
1647 else if (TREE_CODE (DECL_SIZE (field)) != INTEGER_CST
1648 || TREE_OVERFLOW (DECL_SIZE (field)))
1651 = size_binop (PLUS_EXPR, rli->offset,
1652 fold_convert (sizetype,
1653 size_binop (CEIL_DIV_EXPR, rli->bitpos,
1654 bitsize_unit_node)));
1656 = size_binop (PLUS_EXPR, rli->offset, DECL_SIZE_UNIT (field));
1657 rli->bitpos = bitsize_zero_node;
1658 rli->offset_align = MIN (rli->offset_align, desired_align);
1660 if (!multiple_of_p (bitsizetype, DECL_SIZE (field),
1661 bitsize_int (rli->offset_align)))
1663 tree type = strip_array_types (TREE_TYPE (field));
1664 /* The above adjusts offset_align just based on the start of the
1665 field. The field might not have a size that is a multiple of
1666 that offset_align though. If the field is an array of fixed
1667 sized elements, assume there can be any multiple of those
1668 sizes. If it is a variable length aggregate or array of
1669 variable length aggregates, assume worst that the end is
1670 just BITS_PER_UNIT aligned. */
1671 if (TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
1673 if (TREE_INT_CST_LOW (TYPE_SIZE (type)))
1675 unsigned HOST_WIDE_INT sz
1676 = least_bit_hwi (TREE_INT_CST_LOW (TYPE_SIZE (type)));
1677 rli->offset_align = MIN (rli->offset_align, sz);
1681 rli->offset_align = MIN (rli->offset_align, BITS_PER_UNIT);
1684 else if (targetm.ms_bitfield_layout_p (rli->t))
1686 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1688 /* If FIELD is the last field and doesn't end at the full length
1689 of the type then pad the struct out to the full length of the
1691 if (DECL_BIT_FIELD_TYPE (field)
1692 && !integer_zerop (DECL_SIZE (field)))
1694 /* We have to scan, because non-field DECLS are also here. */
1696 while ((probe = DECL_CHAIN (probe)))
1697 if (TREE_CODE (probe) == FIELD_DECL)
1700 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos,
1701 bitsize_int (rli->remaining_in_alignment));
1704 normalize_rli (rli);
1708 rli->bitpos = size_binop (PLUS_EXPR, rli->bitpos, DECL_SIZE (field));
1709 normalize_rli (rli);
1713 /* Assuming that all the fields have been laid out, this function uses
1714 RLI to compute the final TYPE_SIZE, TYPE_ALIGN, etc. for the type
1715 indicated by RLI. */
1718 finalize_record_size (record_layout_info rli)
1720 tree unpadded_size, unpadded_size_unit;
1722 /* Now we want just byte and bit offsets, so set the offset alignment
1723 to be a byte and then normalize. */
1724 rli->offset_align = BITS_PER_UNIT;
1725 normalize_rli (rli);
1727 /* Determine the desired alignment. */
1728 #ifdef ROUND_TYPE_ALIGN
1729 SET_TYPE_ALIGN (rli->t, ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t),
1730 rli->record_align));
1732 SET_TYPE_ALIGN (rli->t, MAX (TYPE_ALIGN (rli->t), rli->record_align));
1735 /* Compute the size so far. Be sure to allow for extra bits in the
1736 size in bytes. We have guaranteed above that it will be no more
1737 than a single byte. */
1738 unpadded_size = rli_size_so_far (rli);
1739 unpadded_size_unit = rli_size_unit_so_far (rli);
1740 if (! integer_zerop (rli->bitpos))
1742 = size_binop (PLUS_EXPR, unpadded_size_unit, size_one_node);
1744 /* Round the size up to be a multiple of the required alignment. */
1745 TYPE_SIZE (rli->t) = round_up (unpadded_size, TYPE_ALIGN (rli->t));
1746 TYPE_SIZE_UNIT (rli->t)
1747 = round_up (unpadded_size_unit, TYPE_ALIGN_UNIT (rli->t));
1749 if (TREE_CONSTANT (unpadded_size)
1750 && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0
1751 && input_location != BUILTINS_LOCATION)
1752 warning (OPT_Wpadded, "padding struct size to alignment boundary");
1754 if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE
1755 && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary
1756 && TREE_CONSTANT (unpadded_size))
1760 #ifdef ROUND_TYPE_ALIGN
1762 = ROUND_TYPE_ALIGN (rli->t, TYPE_ALIGN (rli->t), rli->unpacked_align);
1764 rli->unpacked_align = MAX (TYPE_ALIGN (rli->t), rli->unpacked_align);
1767 unpacked_size = round_up (TYPE_SIZE (rli->t), rli->unpacked_align);
1768 if (simple_cst_equal (unpacked_size, TYPE_SIZE (rli->t)))
1770 if (TYPE_NAME (rli->t))
1774 if (TREE_CODE (TYPE_NAME (rli->t)) == IDENTIFIER_NODE)
1775 name = TYPE_NAME (rli->t);
1777 name = DECL_NAME (TYPE_NAME (rli->t));
1779 if (STRICT_ALIGNMENT)
1780 warning (OPT_Wpacked, "packed attribute causes inefficient "
1781 "alignment for %qE", name);
1783 warning (OPT_Wpacked,
1784 "packed attribute is unnecessary for %qE", name);
1788 if (STRICT_ALIGNMENT)
1789 warning (OPT_Wpacked,
1790 "packed attribute causes inefficient alignment");
1792 warning (OPT_Wpacked, "packed attribute is unnecessary");
1798 /* Compute the TYPE_MODE for the TYPE (which is a RECORD_TYPE). */
1801 compute_record_mode (tree type)
1804 machine_mode mode = VOIDmode;
1806 /* Most RECORD_TYPEs have BLKmode, so we start off assuming that.
1807 However, if possible, we use a mode that fits in a register
1808 instead, in order to allow for better optimization down the
1810 SET_TYPE_MODE (type, BLKmode);
1812 if (! tree_fits_uhwi_p (TYPE_SIZE (type)))
1815 /* A record which has any BLKmode members must itself be
1816 BLKmode; it can't go in a register. Unless the member is
1817 BLKmode only because it isn't aligned. */
1818 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
1820 if (TREE_CODE (field) != FIELD_DECL)
1823 if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
1824 || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
1825 && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
1826 && !(TYPE_SIZE (TREE_TYPE (field)) != 0
1827 && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
1828 || ! tree_fits_uhwi_p (bit_position (field))
1829 || DECL_SIZE (field) == 0
1830 || ! tree_fits_uhwi_p (DECL_SIZE (field)))
1833 /* If this field is the whole struct, remember its mode so
1834 that, say, we can put a double in a class into a DF
1835 register instead of forcing it to live in the stack. */
1836 if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field)))
1837 mode = DECL_MODE (field);
1839 /* With some targets, it is sub-optimal to access an aligned
1840 BLKmode structure as a scalar. */
1841 if (targetm.member_type_forces_blk (field, mode))
1845 /* If we only have one real field; use its mode if that mode's size
1846 matches the type's size. This only applies to RECORD_TYPE. This
1847 does not apply to unions. */
1848 if (TREE_CODE (type) == RECORD_TYPE && mode != VOIDmode
1849 && tree_fits_uhwi_p (TYPE_SIZE (type))
1850 && known_eq (GET_MODE_BITSIZE (mode), tree_to_uhwi (TYPE_SIZE (type))))
1853 mode = mode_for_size_tree (TYPE_SIZE (type), MODE_INT, 1).else_blk ();
1855 /* If structure's known alignment is less than what the scalar
1856 mode would need, and it matters, then stick with BLKmode. */
1859 && ! (TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT
1860 || TYPE_ALIGN (type) >= GET_MODE_ALIGNMENT (mode)))
1862 /* If this is the only reason this type is BLKmode, then
1863 don't force containing types to be BLKmode. */
1864 TYPE_NO_FORCE_BLK (type) = 1;
1868 SET_TYPE_MODE (type, mode);
1871 /* Compute TYPE_SIZE and TYPE_ALIGN for TYPE, once it has been laid
1875 finalize_type_size (tree type)
1877 /* Normally, use the alignment corresponding to the mode chosen.
1878 However, where strict alignment is not required, avoid
1879 over-aligning structures, since most compilers do not do this
1881 if (TYPE_MODE (type) != BLKmode
1882 && TYPE_MODE (type) != VOIDmode
1883 && (STRICT_ALIGNMENT || !AGGREGATE_TYPE_P (type)))
1885 unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
1887 /* Don't override a larger alignment requirement coming from a user
1888 alignment of one of the fields. */
1889 if (mode_align >= TYPE_ALIGN (type))
1891 SET_TYPE_ALIGN (type, mode_align);
1892 TYPE_USER_ALIGN (type) = 0;
1896 /* Do machine-dependent extra alignment. */
1897 #ifdef ROUND_TYPE_ALIGN
1898 SET_TYPE_ALIGN (type,
1899 ROUND_TYPE_ALIGN (type, TYPE_ALIGN (type), BITS_PER_UNIT));
1902 /* If we failed to find a simple way to calculate the unit size
1903 of the type, find it by division. */
1904 if (TYPE_SIZE_UNIT (type) == 0 && TYPE_SIZE (type) != 0)
1905 /* TYPE_SIZE (type) is computed in bitsizetype. After the division, the
1906 result will fit in sizetype. We will get more efficient code using
1907 sizetype, so we force a conversion. */
1908 TYPE_SIZE_UNIT (type)
1909 = fold_convert (sizetype,
1910 size_binop (FLOOR_DIV_EXPR, TYPE_SIZE (type),
1911 bitsize_unit_node));
1913 if (TYPE_SIZE (type) != 0)
1915 TYPE_SIZE (type) = round_up (TYPE_SIZE (type), TYPE_ALIGN (type));
1916 TYPE_SIZE_UNIT (type)
1917 = round_up (TYPE_SIZE_UNIT (type), TYPE_ALIGN_UNIT (type));
1920 /* Evaluate nonconstant sizes only once, either now or as soon as safe. */
1921 if (TYPE_SIZE (type) != 0 && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
1922 TYPE_SIZE (type) = variable_size (TYPE_SIZE (type));
1923 if (TYPE_SIZE_UNIT (type) != 0
1924 && TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST)
1925 TYPE_SIZE_UNIT (type) = variable_size (TYPE_SIZE_UNIT (type));
1927 /* Handle empty records as per the x86-64 psABI. */
1928 TYPE_EMPTY_P (type) = targetm.calls.empty_record_p (type);
1930 /* Also layout any other variants of the type. */
1931 if (TYPE_NEXT_VARIANT (type)
1932 || type != TYPE_MAIN_VARIANT (type))
1935 /* Record layout info of this variant. */
1936 tree size = TYPE_SIZE (type);
1937 tree size_unit = TYPE_SIZE_UNIT (type);
1938 unsigned int align = TYPE_ALIGN (type);
1939 unsigned int precision = TYPE_PRECISION (type);
1940 unsigned int user_align = TYPE_USER_ALIGN (type);
1941 machine_mode mode = TYPE_MODE (type);
1942 bool empty_p = TYPE_EMPTY_P (type);
1944 /* Copy it into all variants. */
1945 for (variant = TYPE_MAIN_VARIANT (type);
1947 variant = TYPE_NEXT_VARIANT (variant))
1949 TYPE_SIZE (variant) = size;
1950 TYPE_SIZE_UNIT (variant) = size_unit;
1951 unsigned valign = align;
1952 if (TYPE_USER_ALIGN (variant))
1953 valign = MAX (valign, TYPE_ALIGN (variant));
1955 TYPE_USER_ALIGN (variant) = user_align;
1956 SET_TYPE_ALIGN (variant, valign);
1957 TYPE_PRECISION (variant) = precision;
1958 SET_TYPE_MODE (variant, mode);
1959 TYPE_EMPTY_P (variant) = empty_p;
1964 /* Return a new underlying object for a bitfield started with FIELD. */
1967 start_bitfield_representative (tree field)
1969 tree repr = make_node (FIELD_DECL);
1970 DECL_FIELD_OFFSET (repr) = DECL_FIELD_OFFSET (field);
1971 /* Force the representative to begin at a BITS_PER_UNIT aligned
1972 boundary - C++ may use tail-padding of a base object to
1973 continue packing bits so the bitfield region does not start
1974 at bit zero (see g++.dg/abi/bitfield5.C for example).
1975 Unallocated bits may happen for other reasons as well,
1976 for example Ada which allows explicit bit-granular structure layout. */
1977 DECL_FIELD_BIT_OFFSET (repr)
1978 = size_binop (BIT_AND_EXPR,
1979 DECL_FIELD_BIT_OFFSET (field),
1980 bitsize_int (~(BITS_PER_UNIT - 1)));
1981 SET_DECL_OFFSET_ALIGN (repr, DECL_OFFSET_ALIGN (field));
1982 DECL_SIZE (repr) = DECL_SIZE (field);
1983 DECL_SIZE_UNIT (repr) = DECL_SIZE_UNIT (field);
1984 DECL_PACKED (repr) = DECL_PACKED (field);
1985 DECL_CONTEXT (repr) = DECL_CONTEXT (field);
1986 /* There are no indirect accesses to this field. If we introduce
1987 some then they have to use the record alias set. This makes
1988 sure to properly conflict with [indirect] accesses to addressable
1989 fields of the bitfield group. */
1990 DECL_NONADDRESSABLE_P (repr) = 1;
1994 /* Finish up a bitfield group that was started by creating the underlying
1995 object REPR with the last field in the bitfield group FIELD. */
1998 finish_bitfield_representative (tree repr, tree field)
2000 unsigned HOST_WIDE_INT bitsize, maxbitsize;
2003 size = size_diffop (DECL_FIELD_OFFSET (field),
2004 DECL_FIELD_OFFSET (repr));
2005 while (TREE_CODE (size) == COMPOUND_EXPR)
2006 size = TREE_OPERAND (size, 1);
2007 gcc_assert (tree_fits_uhwi_p (size));
2008 bitsize = (tree_to_uhwi (size) * BITS_PER_UNIT
2009 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field))
2010 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr))
2011 + tree_to_uhwi (DECL_SIZE (field)));
2013 /* Round up bitsize to multiples of BITS_PER_UNIT. */
2014 bitsize = (bitsize + BITS_PER_UNIT - 1) & ~(BITS_PER_UNIT - 1);
2016 /* Now nothing tells us how to pad out bitsize ... */
2017 nextf = DECL_CHAIN (field);
2018 while (nextf && TREE_CODE (nextf) != FIELD_DECL)
2019 nextf = DECL_CHAIN (nextf);
2023 /* If there was an error, the field may be not laid out
2024 correctly. Don't bother to do anything. */
2025 if (TREE_TYPE (nextf) == error_mark_node)
2027 maxsize = size_diffop (DECL_FIELD_OFFSET (nextf),
2028 DECL_FIELD_OFFSET (repr));
2029 if (tree_fits_uhwi_p (maxsize))
2031 maxbitsize = (tree_to_uhwi (maxsize) * BITS_PER_UNIT
2032 + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (nextf))
2033 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr)));
2034 /* If the group ends within a bitfield nextf does not need to be
2035 aligned to BITS_PER_UNIT. Thus round up. */
2036 maxbitsize = (maxbitsize + BITS_PER_UNIT - 1) & ~(BITS_PER_UNIT - 1);
2039 maxbitsize = bitsize;
2043 /* Note that if the C++ FE sets up tail-padding to be re-used it
2044 creates a as-base variant of the type with TYPE_SIZE adjusted
2045 accordingly. So it is safe to include tail-padding here. */
2046 tree aggsize = lang_hooks.types.unit_size_without_reusable_padding
2047 (DECL_CONTEXT (field));
2048 tree maxsize = size_diffop (aggsize, DECL_FIELD_OFFSET (repr));
2049 /* We cannot generally rely on maxsize to fold to an integer constant,
2050 so use bitsize as fallback for this case. */
2051 if (tree_fits_uhwi_p (maxsize))
2052 maxbitsize = (tree_to_uhwi (maxsize) * BITS_PER_UNIT
2053 - tree_to_uhwi (DECL_FIELD_BIT_OFFSET (repr)));
2055 maxbitsize = bitsize;
2058 /* Only if we don't artificially break up the representative in
2059 the middle of a large bitfield with different possibly
2060 overlapping representatives. And all representatives start
2062 gcc_assert (maxbitsize % BITS_PER_UNIT == 0);
2064 /* Find the smallest nice mode to use. */
2065 opt_scalar_int_mode mode_iter;
2066 FOR_EACH_MODE_IN_CLASS (mode_iter, MODE_INT)
2067 if (GET_MODE_BITSIZE (mode_iter.require ()) >= bitsize)
2070 scalar_int_mode mode;
2071 if (!mode_iter.exists (&mode)
2072 || GET_MODE_BITSIZE (mode) > maxbitsize
2073 || GET_MODE_BITSIZE (mode) > MAX_FIXED_MODE_SIZE)
2075 /* We really want a BLKmode representative only as a last resort,
2076 considering the member b in
2077 struct { int a : 7; int b : 17; int c; } __attribute__((packed));
2078 Otherwise we simply want to split the representative up
2079 allowing for overlaps within the bitfield region as required for
2080 struct { int a : 7; int b : 7;
2081 int c : 10; int d; } __attribute__((packed));
2082 [0, 15] HImode for a and b, [8, 23] HImode for c. */
2083 DECL_SIZE (repr) = bitsize_int (bitsize);
2084 DECL_SIZE_UNIT (repr) = size_int (bitsize / BITS_PER_UNIT);
2085 SET_DECL_MODE (repr, BLKmode);
2086 TREE_TYPE (repr) = build_array_type_nelts (unsigned_char_type_node,
2087 bitsize / BITS_PER_UNIT);
2091 unsigned HOST_WIDE_INT modesize = GET_MODE_BITSIZE (mode);
2092 DECL_SIZE (repr) = bitsize_int (modesize);
2093 DECL_SIZE_UNIT (repr) = size_int (modesize / BITS_PER_UNIT);
2094 SET_DECL_MODE (repr, mode);
2095 TREE_TYPE (repr) = lang_hooks.types.type_for_mode (mode, 1);
2098 /* Remember whether the bitfield group is at the end of the
2099 structure or not. */
2100 DECL_CHAIN (repr) = nextf;
2103 /* Compute and set FIELD_DECLs for the underlying objects we should
2104 use for bitfield access for the structure T. */
2107 finish_bitfield_layout (tree t)
2110 tree repr = NULL_TREE;
2112 /* Unions would be special, for the ease of type-punning optimizations
2113 we could use the underlying type as hint for the representative
2114 if the bitfield would fit and the representative would not exceed
2115 the union in size. */
2116 if (TREE_CODE (t) != RECORD_TYPE)
2119 for (prev = NULL_TREE, field = TYPE_FIELDS (t);
2120 field; field = DECL_CHAIN (field))
2122 if (TREE_CODE (field) != FIELD_DECL)
2125 /* In the C++ memory model, consecutive bit fields in a structure are
2126 considered one memory location and updating a memory location
2127 may not store into adjacent memory locations. */
2129 && DECL_BIT_FIELD_TYPE (field))
2131 /* Start new representative. */
2132 repr = start_bitfield_representative (field);
2135 && ! DECL_BIT_FIELD_TYPE (field))
2137 /* Finish off new representative. */
2138 finish_bitfield_representative (repr, prev);
2141 else if (DECL_BIT_FIELD_TYPE (field))
2143 gcc_assert (repr != NULL_TREE);
2145 /* Zero-size bitfields finish off a representative and
2146 do not have a representative themselves. This is
2147 required by the C++ memory model. */
2148 if (integer_zerop (DECL_SIZE (field)))
2150 finish_bitfield_representative (repr, prev);
2154 /* We assume that either DECL_FIELD_OFFSET of the representative
2155 and each bitfield member is a constant or they are equal.
2156 This is because we need to be able to compute the bit-offset
2157 of each field relative to the representative in get_bit_range
2158 during RTL expansion.
2159 If these constraints are not met, simply force a new
2160 representative to be generated. That will at most
2161 generate worse code but still maintain correctness with
2162 respect to the C++ memory model. */
2163 else if (!((tree_fits_uhwi_p (DECL_FIELD_OFFSET (repr))
2164 && tree_fits_uhwi_p (DECL_FIELD_OFFSET (field)))
2165 || operand_equal_p (DECL_FIELD_OFFSET (repr),
2166 DECL_FIELD_OFFSET (field), 0)))
2168 finish_bitfield_representative (repr, prev);
2169 repr = start_bitfield_representative (field);
2176 DECL_BIT_FIELD_REPRESENTATIVE (field) = repr;
2182 finish_bitfield_representative (repr, prev);
2185 /* Do all of the work required to layout the type indicated by RLI,
2186 once the fields have been laid out. This function will call `free'
2187 for RLI, unless FREE_P is false. Passing a value other than false
2188 for FREE_P is bad practice; this option only exists to support the
2192 finish_record_layout (record_layout_info rli, int free_p)
2196 /* Compute the final size. */
2197 finalize_record_size (rli);
2199 /* Compute the TYPE_MODE for the record. */
2200 compute_record_mode (rli->t);
2202 /* Perform any last tweaks to the TYPE_SIZE, etc. */
2203 finalize_type_size (rli->t);
2205 /* Compute bitfield representatives. */
2206 finish_bitfield_layout (rli->t);
2208 /* Propagate TYPE_PACKED and TYPE_REVERSE_STORAGE_ORDER to variants.
2209 With C++ templates, it is too early to do this when the attribute
2211 for (variant = TYPE_NEXT_VARIANT (rli->t); variant;
2212 variant = TYPE_NEXT_VARIANT (variant))
2214 TYPE_PACKED (variant) = TYPE_PACKED (rli->t);
2215 TYPE_REVERSE_STORAGE_ORDER (variant)
2216 = TYPE_REVERSE_STORAGE_ORDER (rli->t);
2219 /* Lay out any static members. This is done now because their type
2220 may use the record's type. */
2221 while (!vec_safe_is_empty (rli->pending_statics))
2222 layout_decl (rli->pending_statics->pop (), 0);
2227 vec_free (rli->pending_statics);
2233 /* Finish processing a builtin RECORD_TYPE type TYPE. It's name is
2234 NAME, its fields are chained in reverse on FIELDS.
2236 If ALIGN_TYPE is non-null, it is given the same alignment as
2240 finish_builtin_struct (tree type, const char *name, tree fields,
2245 for (tail = NULL_TREE; fields; tail = fields, fields = next)
2247 DECL_FIELD_CONTEXT (fields) = type;
2248 next = DECL_CHAIN (fields);
2249 DECL_CHAIN (fields) = tail;
2251 TYPE_FIELDS (type) = tail;
2255 SET_TYPE_ALIGN (type, TYPE_ALIGN (align_type));
2256 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (align_type);
2257 SET_TYPE_WARN_IF_NOT_ALIGN (type,
2258 TYPE_WARN_IF_NOT_ALIGN (align_type));
2262 #if 0 /* not yet, should get fixed properly later */
2263 TYPE_NAME (type) = make_type_decl (get_identifier (name), type);
2265 TYPE_NAME (type) = build_decl (BUILTINS_LOCATION,
2266 TYPE_DECL, get_identifier (name), type);
2268 TYPE_STUB_DECL (type) = TYPE_NAME (type);
2269 layout_decl (TYPE_NAME (type), 0);
2272 /* Calculate the mode, size, and alignment for TYPE.
2273 For an array type, calculate the element separation as well.
2274 Record TYPE on the chain of permanent or temporary types
2275 so that dbxout will find out about it.
2277 TYPE_SIZE of a type is nonzero if the type has been laid out already.
2278 layout_type does nothing on such a type.
2280 If the type is incomplete, its TYPE_SIZE remains zero. */
2283 layout_type (tree type)
2287 if (type == error_mark_node)
2290 /* We don't want finalize_type_size to copy an alignment attribute to
2291 variants that don't have it. */
2292 type = TYPE_MAIN_VARIANT (type);
2294 /* Do nothing if type has been laid out before. */
2295 if (TYPE_SIZE (type))
2298 switch (TREE_CODE (type))
2301 /* This kind of type is the responsibility
2302 of the language-specific code. */
2309 scalar_int_mode mode
2310 = smallest_int_mode_for_size (TYPE_PRECISION (type));
2311 SET_TYPE_MODE (type, mode);
2312 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
2313 /* Don't set TYPE_PRECISION here, as it may be set by a bitfield. */
2314 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
2320 /* Allow the caller to choose the type mode, which is how decimal
2321 floats are distinguished from binary ones. */
2322 if (TYPE_MODE (type) == VOIDmode)
2324 (type, float_mode_for_size (TYPE_PRECISION (type)).require ());
2325 scalar_float_mode mode = as_a <scalar_float_mode> (TYPE_MODE (type));
2326 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
2327 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
2331 case FIXED_POINT_TYPE:
2333 /* TYPE_MODE (type) has been set already. */
2334 scalar_mode mode = SCALAR_TYPE_MODE (type);
2335 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
2336 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
2341 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
2342 SET_TYPE_MODE (type,
2343 GET_MODE_COMPLEX_MODE (TYPE_MODE (TREE_TYPE (type))));
2345 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
2346 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
2351 poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (type);
2352 tree innertype = TREE_TYPE (type);
2354 /* Find an appropriate mode for the vector type. */
2355 if (TYPE_MODE (type) == VOIDmode)
2356 SET_TYPE_MODE (type,
2357 mode_for_vector (SCALAR_TYPE_MODE (innertype),
2358 nunits).else_blk ());
2360 TYPE_SATURATING (type) = TYPE_SATURATING (TREE_TYPE (type));
2361 TYPE_UNSIGNED (type) = TYPE_UNSIGNED (TREE_TYPE (type));
2362 /* Several boolean vector elements may fit in a single unit. */
2363 if (VECTOR_BOOLEAN_TYPE_P (type)
2364 && type->type_common.mode != BLKmode)
2365 TYPE_SIZE_UNIT (type)
2366 = size_int (GET_MODE_SIZE (type->type_common.mode));
2368 TYPE_SIZE_UNIT (type) = int_const_binop (MULT_EXPR,
2369 TYPE_SIZE_UNIT (innertype),
2371 TYPE_SIZE (type) = int_const_binop
2373 bits_from_bytes (TYPE_SIZE_UNIT (type)),
2374 bitsize_int (BITS_PER_UNIT));
2376 /* For vector types, we do not default to the mode's alignment.
2377 Instead, query a target hook, defaulting to natural alignment.
2378 This prevents ABI changes depending on whether or not native
2379 vector modes are supported. */
2380 SET_TYPE_ALIGN (type, targetm.vector_alignment (type));
2382 /* However, if the underlying mode requires a bigger alignment than
2383 what the target hook provides, we cannot use the mode. For now,
2384 simply reject that case. */
2385 gcc_assert (TYPE_ALIGN (type)
2386 >= GET_MODE_ALIGNMENT (TYPE_MODE (type)));
2391 /* This is an incomplete type and so doesn't have a size. */
2392 SET_TYPE_ALIGN (type, 1);
2393 TYPE_USER_ALIGN (type) = 0;
2394 SET_TYPE_MODE (type, VOIDmode);
2397 case POINTER_BOUNDS_TYPE:
2398 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (TYPE_MODE (type)));
2399 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (TYPE_MODE (type)));
2403 TYPE_SIZE (type) = bitsize_int (POINTER_SIZE);
2404 TYPE_SIZE_UNIT (type) = size_int (POINTER_SIZE_UNITS);
2405 /* A pointer might be MODE_PARTIAL_INT, but ptrdiff_t must be
2406 integral, which may be an __intN. */
2407 SET_TYPE_MODE (type, int_mode_for_size (POINTER_SIZE, 0).require ());
2408 TYPE_PRECISION (type) = POINTER_SIZE;
2413 /* It's hard to see what the mode and size of a function ought to
2414 be, but we do know the alignment is FUNCTION_BOUNDARY, so
2415 make it consistent with that. */
2416 SET_TYPE_MODE (type,
2417 int_mode_for_size (FUNCTION_BOUNDARY, 0).else_blk ());
2418 TYPE_SIZE (type) = bitsize_int (FUNCTION_BOUNDARY);
2419 TYPE_SIZE_UNIT (type) = size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);
2423 case REFERENCE_TYPE:
2425 scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type);
2426 TYPE_SIZE (type) = bitsize_int (GET_MODE_BITSIZE (mode));
2427 TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
2428 TYPE_UNSIGNED (type) = 1;
2429 TYPE_PRECISION (type) = GET_MODE_PRECISION (mode);
2435 tree index = TYPE_DOMAIN (type);
2436 tree element = TREE_TYPE (type);
2438 /* We need to know both bounds in order to compute the size. */
2439 if (index && TYPE_MAX_VALUE (index) && TYPE_MIN_VALUE (index)
2440 && TYPE_SIZE (element))
2442 tree ub = TYPE_MAX_VALUE (index);
2443 tree lb = TYPE_MIN_VALUE (index);
2444 tree element_size = TYPE_SIZE (element);
2447 /* Make sure that an array of zero-sized element is zero-sized
2448 regardless of its extent. */
2449 if (integer_zerop (element_size))
2450 length = size_zero_node;
2452 /* The computation should happen in the original signedness so
2453 that (possible) negative values are handled appropriately
2454 when determining overflow. */
2457 /* ??? When it is obvious that the range is signed
2458 represent it using ssizetype. */
2459 if (TREE_CODE (lb) == INTEGER_CST
2460 && TREE_CODE (ub) == INTEGER_CST
2461 && TYPE_UNSIGNED (TREE_TYPE (lb))
2462 && tree_int_cst_lt (ub, lb))
2464 lb = wide_int_to_tree (ssizetype,
2465 offset_int::from (wi::to_wide (lb),
2467 ub = wide_int_to_tree (ssizetype,
2468 offset_int::from (wi::to_wide (ub),
2472 = fold_convert (sizetype,
2473 size_binop (PLUS_EXPR,
2474 build_int_cst (TREE_TYPE (lb), 1),
2475 size_binop (MINUS_EXPR, ub, lb)));
2478 /* ??? We have no way to distinguish a null-sized array from an
2479 array spanning the whole sizetype range, so we arbitrarily
2480 decide that [0, -1] is the only valid representation. */
2481 if (integer_zerop (length)
2482 && TREE_OVERFLOW (length)
2483 && integer_zerop (lb))
2484 length = size_zero_node;
2486 TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
2487 bits_from_bytes (length));
2489 /* If we know the size of the element, calculate the total size
2490 directly, rather than do some division thing below. This
2491 optimization helps Fortran assumed-size arrays (where the
2492 size of the array is determined at runtime) substantially. */
2493 if (TYPE_SIZE_UNIT (element))
2494 TYPE_SIZE_UNIT (type)
2495 = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (element), length);
2498 /* Now round the alignment and size,
2499 using machine-dependent criteria if any. */
2501 unsigned align = TYPE_ALIGN (element);
2502 if (TYPE_USER_ALIGN (type))
2503 align = MAX (align, TYPE_ALIGN (type));
2505 TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (element);
2506 if (!TYPE_WARN_IF_NOT_ALIGN (type))
2507 SET_TYPE_WARN_IF_NOT_ALIGN (type,
2508 TYPE_WARN_IF_NOT_ALIGN (element));
2509 #ifdef ROUND_TYPE_ALIGN
2510 align = ROUND_TYPE_ALIGN (type, align, BITS_PER_UNIT);
2512 align = MAX (align, BITS_PER_UNIT);
2514 SET_TYPE_ALIGN (type, align);
2515 SET_TYPE_MODE (type, BLKmode);
2516 if (TYPE_SIZE (type) != 0
2517 && ! targetm.member_type_forces_blk (type, VOIDmode)
2518 /* BLKmode elements force BLKmode aggregate;
2519 else extract/store fields may lose. */
2520 && (TYPE_MODE (TREE_TYPE (type)) != BLKmode
2521 || TYPE_NO_FORCE_BLK (TREE_TYPE (type))))
2523 SET_TYPE_MODE (type, mode_for_array (TREE_TYPE (type),
2525 if (TYPE_MODE (type) != BLKmode
2526 && STRICT_ALIGNMENT && TYPE_ALIGN (type) < BIGGEST_ALIGNMENT
2527 && TYPE_ALIGN (type) < GET_MODE_ALIGNMENT (TYPE_MODE (type)))
2529 TYPE_NO_FORCE_BLK (type) = 1;
2530 SET_TYPE_MODE (type, BLKmode);
2533 if (AGGREGATE_TYPE_P (element))
2534 TYPE_TYPELESS_STORAGE (type) = TYPE_TYPELESS_STORAGE (element);
2535 /* When the element size is constant, check that it is at least as
2536 large as the element alignment. */
2537 if (TYPE_SIZE_UNIT (element)
2538 && TREE_CODE (TYPE_SIZE_UNIT (element)) == INTEGER_CST
2539 /* If TYPE_SIZE_UNIT overflowed, then it is certainly larger than
2541 && !TREE_OVERFLOW (TYPE_SIZE_UNIT (element))
2542 && !integer_zerop (TYPE_SIZE_UNIT (element))
2543 && compare_tree_int (TYPE_SIZE_UNIT (element),
2544 TYPE_ALIGN_UNIT (element)) < 0)
2545 error ("alignment of array elements is greater than element size");
2551 case QUAL_UNION_TYPE:
2554 record_layout_info rli;
2556 /* Initialize the layout information. */
2557 rli = start_record_layout (type);
2559 /* If this is a QUAL_UNION_TYPE, we want to process the fields
2560 in the reverse order in building the COND_EXPR that denotes
2561 its size. We reverse them again later. */
2562 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2563 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2565 /* Place all the fields. */
2566 for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
2567 place_field (rli, field);
2569 if (TREE_CODE (type) == QUAL_UNION_TYPE)
2570 TYPE_FIELDS (type) = nreverse (TYPE_FIELDS (type));
2572 /* Finish laying out the record. */
2573 finish_record_layout (rli, /*free_p=*/true);
2581 /* Compute the final TYPE_SIZE, TYPE_ALIGN, etc. for TYPE. For
2582 records and unions, finish_record_layout already called this
2584 if (!RECORD_OR_UNION_TYPE_P (type))
2585 finalize_type_size (type);
2587 /* We should never see alias sets on incomplete aggregates. And we
2588 should not call layout_type on not incomplete aggregates. */
2589 if (AGGREGATE_TYPE_P (type))
2590 gcc_assert (!TYPE_ALIAS_SET_KNOWN_P (type));
2593 /* Return the least alignment required for type TYPE. */
2596 min_align_of_type (tree type)
2598 unsigned int align = TYPE_ALIGN (type);
2599 if (!TYPE_USER_ALIGN (type))
2601 align = MIN (align, BIGGEST_ALIGNMENT);
2602 #ifdef BIGGEST_FIELD_ALIGNMENT
2603 align = MIN (align, BIGGEST_FIELD_ALIGNMENT);
2605 unsigned int field_align = align;
2606 #ifdef ADJUST_FIELD_ALIGN
2607 field_align = ADJUST_FIELD_ALIGN (NULL_TREE, type, field_align);
2609 align = MIN (align, field_align);
2611 return align / BITS_PER_UNIT;
2614 /* Create and return a type for signed integers of PRECISION bits. */
2617 make_signed_type (int precision)
2619 tree type = make_node (INTEGER_TYPE);
2621 TYPE_PRECISION (type) = precision;
2623 fixup_signed_type (type);
2627 /* Create and return a type for unsigned integers of PRECISION bits. */
2630 make_unsigned_type (int precision)
2632 tree type = make_node (INTEGER_TYPE);
2634 TYPE_PRECISION (type) = precision;
2636 fixup_unsigned_type (type);
2640 /* Create and return a type for fract of PRECISION bits, UNSIGNEDP,
2644 make_fract_type (int precision, int unsignedp, int satp)
2646 tree type = make_node (FIXED_POINT_TYPE);
2648 TYPE_PRECISION (type) = precision;
2651 TYPE_SATURATING (type) = 1;
2653 /* Lay out the type: set its alignment, size, etc. */
2654 TYPE_UNSIGNED (type) = unsignedp;
2655 enum mode_class mclass = unsignedp ? MODE_UFRACT : MODE_FRACT;
2656 SET_TYPE_MODE (type, mode_for_size (precision, mclass, 0).require ());
2662 /* Create and return a type for accum of PRECISION bits, UNSIGNEDP,
2666 make_accum_type (int precision, int unsignedp, int satp)
2668 tree type = make_node (FIXED_POINT_TYPE);
2670 TYPE_PRECISION (type) = precision;
2673 TYPE_SATURATING (type) = 1;
2675 /* Lay out the type: set its alignment, size, etc. */
2676 TYPE_UNSIGNED (type) = unsignedp;
2677 enum mode_class mclass = unsignedp ? MODE_UACCUM : MODE_ACCUM;
2678 SET_TYPE_MODE (type, mode_for_size (precision, mclass, 0).require ());
2684 /* Initialize sizetypes so layout_type can use them. */
2687 initialize_sizetypes (void)
2689 int precision, bprecision;
2691 /* Get sizetypes precision from the SIZE_TYPE target macro. */
2692 if (strcmp (SIZETYPE, "unsigned int") == 0)
2693 precision = INT_TYPE_SIZE;
2694 else if (strcmp (SIZETYPE, "long unsigned int") == 0)
2695 precision = LONG_TYPE_SIZE;
2696 else if (strcmp (SIZETYPE, "long long unsigned int") == 0)
2697 precision = LONG_LONG_TYPE_SIZE;
2698 else if (strcmp (SIZETYPE, "short unsigned int") == 0)
2699 precision = SHORT_TYPE_SIZE;
2705 for (i = 0; i < NUM_INT_N_ENTS; i++)
2706 if (int_n_enabled_p[i])
2709 sprintf (name, "__int%d unsigned", int_n_data[i].bitsize);
2711 if (strcmp (name, SIZETYPE) == 0)
2713 precision = int_n_data[i].bitsize;
2716 if (precision == -1)
2721 = MIN (precision + LOG2_BITS_PER_UNIT + 1, MAX_FIXED_MODE_SIZE);
2722 bprecision = GET_MODE_PRECISION (smallest_int_mode_for_size (bprecision));
2723 if (bprecision > HOST_BITS_PER_DOUBLE_INT)
2724 bprecision = HOST_BITS_PER_DOUBLE_INT;
2726 /* Create stubs for sizetype and bitsizetype so we can create constants. */
2727 sizetype = make_node (INTEGER_TYPE);
2728 TYPE_NAME (sizetype) = get_identifier ("sizetype");
2729 TYPE_PRECISION (sizetype) = precision;
2730 TYPE_UNSIGNED (sizetype) = 1;
2731 bitsizetype = make_node (INTEGER_TYPE);
2732 TYPE_NAME (bitsizetype) = get_identifier ("bitsizetype");
2733 TYPE_PRECISION (bitsizetype) = bprecision;
2734 TYPE_UNSIGNED (bitsizetype) = 1;
2736 /* Now layout both types manually. */
2737 scalar_int_mode mode = smallest_int_mode_for_size (precision);
2738 SET_TYPE_MODE (sizetype, mode);
2739 SET_TYPE_ALIGN (sizetype, GET_MODE_ALIGNMENT (TYPE_MODE (sizetype)));
2740 TYPE_SIZE (sizetype) = bitsize_int (precision);
2741 TYPE_SIZE_UNIT (sizetype) = size_int (GET_MODE_SIZE (mode));
2742 set_min_and_max_values_for_integral_type (sizetype, precision, UNSIGNED);
2744 mode = smallest_int_mode_for_size (bprecision);
2745 SET_TYPE_MODE (bitsizetype, mode);
2746 SET_TYPE_ALIGN (bitsizetype, GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype)));
2747 TYPE_SIZE (bitsizetype) = bitsize_int (bprecision);
2748 TYPE_SIZE_UNIT (bitsizetype) = size_int (GET_MODE_SIZE (mode));
2749 set_min_and_max_values_for_integral_type (bitsizetype, bprecision, UNSIGNED);
2751 /* Create the signed variants of *sizetype. */
2752 ssizetype = make_signed_type (TYPE_PRECISION (sizetype));
2753 TYPE_NAME (ssizetype) = get_identifier ("ssizetype");
2754 sbitsizetype = make_signed_type (TYPE_PRECISION (bitsizetype));
2755 TYPE_NAME (sbitsizetype) = get_identifier ("sbitsizetype");
2758 /* TYPE is an integral type, i.e., an INTEGRAL_TYPE, ENUMERAL_TYPE
2759 or BOOLEAN_TYPE. Set TYPE_MIN_VALUE and TYPE_MAX_VALUE
2760 for TYPE, based on the PRECISION and whether or not the TYPE
2761 IS_UNSIGNED. PRECISION need not correspond to a width supported
2762 natively by the hardware; for example, on a machine with 8-bit,
2763 16-bit, and 32-bit register modes, PRECISION might be 7, 23, or
2767 set_min_and_max_values_for_integral_type (tree type,
2771 /* For bitfields with zero width we end up creating integer types
2772 with zero precision. Don't assign any minimum/maximum values
2773 to those types, they don't have any valid value. */
2777 TYPE_MIN_VALUE (type)
2778 = wide_int_to_tree (type, wi::min_value (precision, sgn));
2779 TYPE_MAX_VALUE (type)
2780 = wide_int_to_tree (type, wi::max_value (precision, sgn));
2783 /* Set the extreme values of TYPE based on its precision in bits,
2784 then lay it out. Used when make_signed_type won't do
2785 because the tree code is not INTEGER_TYPE. */
2788 fixup_signed_type (tree type)
2790 int precision = TYPE_PRECISION (type);
2792 set_min_and_max_values_for_integral_type (type, precision, SIGNED);
2794 /* Lay out the type: set its alignment, size, etc. */
2798 /* Set the extreme values of TYPE based on its precision in bits,
2799 then lay it out. This is used both in `make_unsigned_type'
2800 and for enumeral types. */
2803 fixup_unsigned_type (tree type)
2805 int precision = TYPE_PRECISION (type);
2807 TYPE_UNSIGNED (type) = 1;
2809 set_min_and_max_values_for_integral_type (type, precision, UNSIGNED);
2811 /* Lay out the type: set its alignment, size, etc. */
2815 /* Construct an iterator for a bitfield that spans BITSIZE bits,
2818 BITREGION_START is the bit position of the first bit in this
2819 sequence of bit fields. BITREGION_END is the last bit in this
2820 sequence. If these two fields are non-zero, we should restrict the
2821 memory access to that range. Otherwise, we are allowed to touch
2822 any adjacent non bit-fields.
2824 ALIGN is the alignment of the underlying object in bits.
2825 VOLATILEP says whether the bitfield is volatile. */
2827 bit_field_mode_iterator
2828 ::bit_field_mode_iterator (HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
2829 poly_int64 bitregion_start,
2830 poly_int64 bitregion_end,
2831 unsigned int align, bool volatilep)
2832 : m_mode (NARROWEST_INT_MODE), m_bitsize (bitsize),
2833 m_bitpos (bitpos), m_bitregion_start (bitregion_start),
2834 m_bitregion_end (bitregion_end), m_align (align),
2835 m_volatilep (volatilep), m_count (0)
2837 if (known_eq (m_bitregion_end, 0))
2839 /* We can assume that any aligned chunk of ALIGN bits that overlaps
2840 the bitfield is mapped and won't trap, provided that ALIGN isn't
2841 too large. The cap is the biggest required alignment for data,
2842 or at least the word size. And force one such chunk at least. */
2843 unsigned HOST_WIDE_INT units
2844 = MIN (align, MAX (BIGGEST_ALIGNMENT, BITS_PER_WORD));
2847 HOST_WIDE_INT end = bitpos + bitsize + units - 1;
2848 m_bitregion_end = end - end % units - 1;
2852 /* Calls to this function return successively larger modes that can be used
2853 to represent the bitfield. Return true if another bitfield mode is
2854 available, storing it in *OUT_MODE if so. */
2857 bit_field_mode_iterator::next_mode (scalar_int_mode *out_mode)
2859 scalar_int_mode mode;
2860 for (; m_mode.exists (&mode); m_mode = GET_MODE_WIDER_MODE (mode))
2862 unsigned int unit = GET_MODE_BITSIZE (mode);
2864 /* Skip modes that don't have full precision. */
2865 if (unit != GET_MODE_PRECISION (mode))
2868 /* Stop if the mode is too wide to handle efficiently. */
2869 if (unit > MAX_FIXED_MODE_SIZE)
2872 /* Don't deliver more than one multiword mode; the smallest one
2874 if (m_count > 0 && unit > BITS_PER_WORD)
2877 /* Skip modes that are too small. */
2878 unsigned HOST_WIDE_INT substart = (unsigned HOST_WIDE_INT) m_bitpos % unit;
2879 unsigned HOST_WIDE_INT subend = substart + m_bitsize;
2883 /* Stop if the mode goes outside the bitregion. */
2884 HOST_WIDE_INT start = m_bitpos - substart;
2885 if (maybe_ne (m_bitregion_start, 0)
2886 && maybe_lt (start, m_bitregion_start))
2888 HOST_WIDE_INT end = start + unit;
2889 if (maybe_gt (end, m_bitregion_end + 1))
2892 /* Stop if the mode requires too much alignment. */
2893 if (GET_MODE_ALIGNMENT (mode) > m_align
2894 && targetm.slow_unaligned_access (mode, m_align))
2898 m_mode = GET_MODE_WIDER_MODE (mode);
2905 /* Return true if smaller modes are generally preferred for this kind
2909 bit_field_mode_iterator::prefer_smaller_modes ()
2912 ? targetm.narrow_volatile_bitfield ()
2913 : !SLOW_BYTE_ACCESS);
2916 /* Find the best machine mode to use when referencing a bit field of length
2917 BITSIZE bits starting at BITPOS.
2919 BITREGION_START is the bit position of the first bit in this
2920 sequence of bit fields. BITREGION_END is the last bit in this
2921 sequence. If these two fields are non-zero, we should restrict the
2922 memory access to that range. Otherwise, we are allowed to touch
2923 any adjacent non bit-fields.
2925 The chosen mode must have no more than LARGEST_MODE_BITSIZE bits.
2926 INT_MAX is a suitable value for LARGEST_MODE_BITSIZE if the caller
2927 doesn't want to apply a specific limit.
2929 If no mode meets all these conditions, we return VOIDmode.
2931 The underlying object is known to be aligned to a boundary of ALIGN bits.
2933 If VOLATILEP is false and SLOW_BYTE_ACCESS is false, we return the
2934 smallest mode meeting these conditions.
2936 If VOLATILEP is false and SLOW_BYTE_ACCESS is true, we return the
2937 largest mode (but a mode no wider than UNITS_PER_WORD) that meets
2940 If VOLATILEP is true the narrow_volatile_bitfields target hook is used to
2941 decide which of the above modes should be used. */
2944 get_best_mode (int bitsize, int bitpos,
2945 poly_uint64 bitregion_start, poly_uint64 bitregion_end,
2947 unsigned HOST_WIDE_INT largest_mode_bitsize, bool volatilep,
2948 scalar_int_mode *best_mode)
2950 bit_field_mode_iterator iter (bitsize, bitpos, bitregion_start,
2951 bitregion_end, align, volatilep);
2952 scalar_int_mode mode;
2954 while (iter.next_mode (&mode)
2955 /* ??? For historical reasons, reject modes that would normally
2956 receive greater alignment, even if unaligned accesses are
2957 acceptable. This has both advantages and disadvantages.
2958 Removing this check means that something like:
2960 struct s { unsigned int x; unsigned int y; };
2961 int f (struct s *s) { return s->x == 0 && s->y == 0; }
2963 can be implemented using a single load and compare on
2964 64-bit machines that have no alignment restrictions.
2965 For example, on powerpc64-linux-gnu, we would generate:
2987 However, accessing more than one field can make life harder
2988 for the gimple optimizers. For example, gcc.dg/vect/bb-slp-5.c
2989 has a series of unsigned short copies followed by a series of
2990 unsigned short comparisons. With this check, both the copies
2991 and comparisons remain 16-bit accesses and FRE is able
2992 to eliminate the latter. Without the check, the comparisons
2993 can be done using 2 64-bit operations, which FRE isn't able
2994 to handle in the same way.
2996 Either way, it would probably be worth disabling this check
2997 during expand. One particular example where removing the
2998 check would help is the get_best_mode call in store_bit_field.
2999 If we are given a memory bitregion of 128 bits that is aligned
3000 to a 64-bit boundary, and the bitfield we want to modify is
3001 in the second half of the bitregion, this check causes
3002 store_bitfield to turn the memory into a 64-bit reference
3003 to the _first_ half of the region. We later use
3004 adjust_bitfield_address to get a reference to the correct half,
3005 but doing so looks to adjust_bitfield_address as though we are
3006 moving past the end of the original object, so it drops the
3007 associated MEM_EXPR and MEM_OFFSET. Removing the check
3008 causes store_bit_field to keep a 128-bit memory reference,
3009 so that the final bitfield reference still has a MEM_EXPR
3011 && GET_MODE_ALIGNMENT (mode) <= align
3012 && GET_MODE_BITSIZE (mode) <= largest_mode_bitsize)
3016 if (iter.prefer_smaller_modes ())
3023 /* Gets minimal and maximal values for MODE (signed or unsigned depending on
3024 SIGN). The returned constants are made to be usable in TARGET_MODE. */
3027 get_mode_bounds (scalar_int_mode mode, int sign,
3028 scalar_int_mode target_mode,
3029 rtx *mmin, rtx *mmax)
3031 unsigned size = GET_MODE_PRECISION (mode);
3032 unsigned HOST_WIDE_INT min_val, max_val;
3034 gcc_assert (size <= HOST_BITS_PER_WIDE_INT);
3036 /* Special case BImode, which has values 0 and STORE_FLAG_VALUE. */
3039 if (STORE_FLAG_VALUE < 0)
3041 min_val = STORE_FLAG_VALUE;
3047 max_val = STORE_FLAG_VALUE;
3052 min_val = -(HOST_WIDE_INT_1U << (size - 1));
3053 max_val = (HOST_WIDE_INT_1U << (size - 1)) - 1;
3058 max_val = (HOST_WIDE_INT_1U << (size - 1) << 1) - 1;
3061 *mmin = gen_int_mode (min_val, target_mode);
3062 *mmax = gen_int_mode (max_val, target_mode);
3065 #include "gt-stor-layout.h"