1 /* Common block and equivalence list handling
2 Copyright (C) 2000, 2003, 2004, 2005, 2006, 2007, 2008
3 Free Software Foundation, Inc.
4 Contributed by Canqun Yang <canqun@nudt.edu.cn>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* The core algorithm is based on Andy Vaught's g95 tree. Also the
23 way to build UNION_TYPE is borrowed from Richard Henderson.
25 Transform common blocks. An integral part of this is processing
26 equivalence variables. Equivalenced variables that are not in a
27 common block end up in a private block of their own.
29 Each common block or local equivalence list is declared as a union.
30 Variables within the block are represented as a field within the
31 block with the proper offset.
33 So if two variables are equivalenced, they just point to a common
36 Mathematically, laying out an equivalence block is equivalent to
37 solving a linear system of equations. The matrix is usually a
38 sparse matrix in which each row contains all zero elements except
39 for a +1 and a -1, a sort of a generalized Vandermonde matrix. The
40 matrix is usually block diagonal. The system can be
41 overdetermined, underdetermined or have a unique solution. If the
42 system is inconsistent, the program is not standard conforming.
43 The solution vector is integral, since all of the pivots are +1 or -1.
45 How we lay out an equivalence block is a little less complicated.
46 In an equivalence list with n elements, there are n-1 conditions to
47 be satisfied. The conditions partition the variables into what we
48 will call segments. If A and B are equivalenced then A and B are
49 in the same segment. If B and C are equivalenced as well, then A,
50 B and C are in a segment and so on. Each segment is a block of
51 memory that has one or more variables equivalenced in some way. A
52 common block is made up of a series of segments that are joined one
53 after the other. In the linear system, a segment is a block
56 To lay out a segment we first start with some variable and
57 determine its length. The first variable is assumed to start at
58 offset one and extends to however long it is. We then traverse the
59 list of equivalences to find an unused condition that involves at
60 least one of the variables currently in the segment.
62 Each equivalence condition amounts to the condition B+b=C+c where B
63 and C are the offsets of the B and C variables, and b and c are
64 constants which are nonzero for array elements, substrings or
65 structure components. So for
67 EQUIVALENCE(B(2), C(3))
69 B + 2*size of B's elements = C + 3*size of C's elements.
71 If B and C are known we check to see if the condition already
72 holds. If B is known we can solve for C. Since we know the length
73 of C, we can see if the minimum and maximum extents of the segment
74 are affected. Eventually, we make a full pass through the
75 equivalence list without finding any new conditions and the segment
78 At this point, the segment is added to the current common block.
79 Since we know the minimum extent of the segment, everything in the
80 segment is translated to its position in the common block. The
81 usual case here is that there are no equivalence statements and the
82 common block is series of segments with one variable each, which is
83 a diagonal matrix in the matrix formulation.
85 Each segment is described by a chain of segment_info structures. Each
86 segment_info structure describes the extents of a single variable within
87 the segment. This list is maintained in the order the elements are
88 positioned withing the segment. If two elements have the same starting
89 offset the smaller will come first. If they also have the same size their
90 ordering is undefined.
92 Once all common blocks have been created, the list of equivalences
93 is examined for still-unused equivalence conditions. We create a
94 block for each merged equivalence list. */
98 #include "coretypes.h"
104 #include "gfortran.h"
106 #include "trans-types.h"
107 #include "trans-const.h"
108 #include "target-memory.h"
111 /* Holds a single variable in an equivalence set. */
112 typedef struct segment_info
115 HOST_WIDE_INT offset;
116 HOST_WIDE_INT length;
117 /* This will contain the field type until the field is created. */
119 struct segment_info *next;
122 static segment_info * current_segment;
123 static gfc_namespace *gfc_common_ns = NULL;
126 /* Make a segment_info based on a symbol. */
128 static segment_info *
129 get_segment_info (gfc_symbol * sym, HOST_WIDE_INT offset)
133 /* Make sure we've got the character length. */
134 if (sym->ts.type == BT_CHARACTER)
135 gfc_conv_const_charlen (sym->ts.u.cl);
137 /* Create the segment_info and fill it in. */
138 s = (segment_info *) gfc_getmem (sizeof (segment_info));
140 /* We will use this type when building the segment aggregate type. */
141 s->field = gfc_sym_type (sym);
142 s->length = int_size_in_bytes (s->field);
149 /* Add a copy of a segment list to the namespace. This is specifically for
150 equivalence segments, so that dependency checking can be done on
151 equivalence group members. */
154 copy_equiv_list_to_ns (segment_info *c)
160 l = (gfc_equiv_list *) gfc_getmem (sizeof (gfc_equiv_list));
162 l->next = c->sym->ns->equiv_lists;
163 c->sym->ns->equiv_lists = l;
165 for (f = c; f; f = f->next)
167 s = (gfc_equiv_info *) gfc_getmem (sizeof (gfc_equiv_info));
171 s->offset = f->offset;
172 s->length = f->length;
177 /* Add combine segment V and segment LIST. */
179 static segment_info *
180 add_segments (segment_info *list, segment_info *v)
191 /* Find the location of the new element. */
194 if (v->offset < s->offset)
196 if (v->offset == s->offset
197 && v->length <= s->length)
204 /* Insert the new element in between p and s. */
220 /* Construct mangled common block name from symbol name. */
222 /* We need the bind(c) flag to tell us how/if we should mangle the symbol
223 name. There are few calls to this function, so few places that this
224 would need to be added. At the moment, there is only one call, in
225 build_common_decl(). We can't attempt to look up the common block
226 because we may be building it for the first time and therefore, it won't
227 be in the common_root. We also need the binding label, if it's bind(c).
228 Therefore, send in the pointer to the common block, so whatever info we
229 have so far can be used. All of the necessary info should be available
230 in the gfc_common_head by now, so it should be accurate to test the
231 isBindC flag and use the binding label given if it is bind(c).
233 We may NOT know yet if it's bind(c) or not, but we can try at least.
234 Will have to figure out what to do later if it's labeled bind(c)
235 after this is called. */
238 gfc_sym_mangled_common_id (gfc_common_head *com)
241 char mangled_name[GFC_MAX_MANGLED_SYMBOL_LEN + 1];
242 char name[GFC_MAX_SYMBOL_LEN + 1];
244 /* Get the name out of the common block pointer. */
245 strcpy (name, com->name);
247 /* If we're suppose to do a bind(c). */
248 if (com->is_bind_c == 1 && com->binding_label[0] != '\0')
249 return get_identifier (com->binding_label);
251 if (strcmp (name, BLANK_COMMON_NAME) == 0)
252 return get_identifier (name);
254 if (gfc_option.flag_underscoring)
256 has_underscore = strchr (name, '_') != 0;
257 if (gfc_option.flag_second_underscore && has_underscore)
258 snprintf (mangled_name, sizeof mangled_name, "%s__", name);
260 snprintf (mangled_name, sizeof mangled_name, "%s_", name);
262 return get_identifier (mangled_name);
265 return get_identifier (name);
269 /* Build a field declaration for a common variable or a local equivalence
273 build_field (segment_info *h, tree union_type, record_layout_info rli)
277 HOST_WIDE_INT offset = h->offset;
278 unsigned HOST_WIDE_INT desired_align, known_align;
280 name = get_identifier (h->sym->name);
281 field = build_decl (h->sym->declared_at.lb->location,
282 FIELD_DECL, name, h->field);
283 known_align = (offset & -offset) * BITS_PER_UNIT;
284 if (known_align == 0 || known_align > BIGGEST_ALIGNMENT)
285 known_align = BIGGEST_ALIGNMENT;
287 desired_align = update_alignment_for_field (rli, field, known_align);
288 if (desired_align > known_align)
289 DECL_PACKED (field) = 1;
291 DECL_FIELD_CONTEXT (field) = union_type;
292 DECL_FIELD_OFFSET (field) = size_int (offset);
293 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
294 SET_DECL_OFFSET_ALIGN (field, known_align);
296 rli->offset = size_binop (MAX_EXPR, rli->offset,
297 size_binop (PLUS_EXPR,
298 DECL_FIELD_OFFSET (field),
299 DECL_SIZE_UNIT (field)));
300 /* If this field is assigned to a label, we create another two variables.
301 One will hold the address of target label or format label. The other will
302 hold the length of format label string. */
303 if (h->sym->attr.assign)
308 gfc_allocate_lang_decl (field);
309 GFC_DECL_ASSIGN (field) = 1;
310 len = gfc_create_var_np (gfc_charlen_type_node,h->sym->name);
311 addr = gfc_create_var_np (pvoid_type_node, h->sym->name);
312 TREE_STATIC (len) = 1;
313 TREE_STATIC (addr) = 1;
314 DECL_INITIAL (len) = build_int_cst (NULL_TREE, -2);
315 gfc_set_decl_location (len, &h->sym->declared_at);
316 gfc_set_decl_location (addr, &h->sym->declared_at);
317 GFC_DECL_STRING_LEN (field) = pushdecl_top_level (len);
318 GFC_DECL_ASSIGN_ADDR (field) = pushdecl_top_level (addr);
321 /* If this field is volatile, mark it. */
322 if (h->sym->attr.volatile_)
325 TREE_THIS_VOLATILE (field) = 1;
326 new_type = build_qualified_type (TREE_TYPE (field), TYPE_QUAL_VOLATILE);
327 TREE_TYPE (field) = new_type;
334 /* Get storage for local equivalence. */
337 build_equiv_decl (tree union_type, bool is_init, bool is_saved)
341 static int serial = 0;
345 decl = gfc_create_var (union_type, "equiv");
346 TREE_STATIC (decl) = 1;
347 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
351 snprintf (name, sizeof (name), "equiv.%d", serial++);
352 decl = build_decl (input_location,
353 VAR_DECL, get_identifier (name), union_type);
354 DECL_ARTIFICIAL (decl) = 1;
355 DECL_IGNORED_P (decl) = 1;
357 if (!gfc_can_put_var_on_stack (DECL_SIZE_UNIT (decl))
359 TREE_STATIC (decl) = 1;
361 TREE_ADDRESSABLE (decl) = 1;
362 TREE_USED (decl) = 1;
363 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
365 /* The source location has been lost, and doesn't really matter.
366 We need to set it to something though. */
367 gfc_set_decl_location (decl, &gfc_current_locus);
369 gfc_add_decl_to_function (decl);
375 /* Get storage for common block. */
378 build_common_decl (gfc_common_head *com, tree union_type, bool is_init)
380 gfc_symbol *common_sym;
383 /* Create a namespace to store symbols for common blocks. */
384 if (gfc_common_ns == NULL)
385 gfc_common_ns = gfc_get_namespace (NULL, 0);
387 gfc_get_symbol (com->name, gfc_common_ns, &common_sym);
388 decl = common_sym->backend_decl;
390 /* Update the size of this common block as needed. */
391 if (decl != NULL_TREE)
393 tree size = TYPE_SIZE_UNIT (union_type);
394 if (tree_int_cst_lt (DECL_SIZE_UNIT (decl), size))
396 /* Named common blocks of the same name shall be of the same size
397 in all scoping units of a program in which they appear, but
398 blank common blocks may be of different sizes. */
399 if (strcmp (com->name, BLANK_COMMON_NAME))
400 gfc_warning ("Named COMMON block '%s' at %L shall be of the "
401 "same size", com->name, &com->where);
402 DECL_SIZE_UNIT (decl) = size;
403 TREE_TYPE (decl) = union_type;
407 /* If this common block has been declared in a previous program unit,
408 and either it is already initialized or there is no new initialization
409 for it, just return. */
410 if ((decl != NULL_TREE) && (!is_init || DECL_INITIAL (decl)))
413 /* If there is no backend_decl for the common block, build it. */
414 if (decl == NULL_TREE)
416 decl = build_decl (input_location,
417 VAR_DECL, get_identifier (com->name), union_type);
418 gfc_set_decl_assembler_name (decl, gfc_sym_mangled_common_id (com));
419 TREE_PUBLIC (decl) = 1;
420 TREE_STATIC (decl) = 1;
421 DECL_IGNORED_P (decl) = 1;
423 DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
426 /* Do not set the alignment for bind(c) common blocks to
427 BIGGEST_ALIGNMENT because that won't match what C does. Also,
428 for common blocks with one element, the alignment must be
429 that of the field within the common block in order to match
431 tree field = NULL_TREE;
432 field = TYPE_FIELDS (TREE_TYPE (decl));
433 if (TREE_CHAIN (field) == NULL_TREE)
434 DECL_ALIGN (decl) = TYPE_ALIGN (TREE_TYPE (field));
436 DECL_USER_ALIGN (decl) = 0;
437 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
439 gfc_set_decl_location (decl, &com->where);
441 if (com->threadprivate)
442 DECL_TLS_MODEL (decl) = decl_default_tls_model (decl);
444 /* Place the back end declaration for this common block in
445 GLOBAL_BINDING_LEVEL. */
446 common_sym->backend_decl = pushdecl_top_level (decl);
449 /* Has no initial values. */
452 DECL_INITIAL (decl) = NULL_TREE;
453 DECL_COMMON (decl) = 1;
454 DECL_DEFER_OUTPUT (decl) = 1;
458 DECL_INITIAL (decl) = error_mark_node;
459 DECL_COMMON (decl) = 0;
460 DECL_DEFER_OUTPUT (decl) = 0;
466 /* Return a field that is the size of the union, if an equivalence has
467 overlapping initializers. Merge the initializers into a single
468 initializer for this new field, then free the old ones. */
471 get_init_field (segment_info *head, tree union_type, tree *field_init,
472 record_layout_info rli)
475 HOST_WIDE_INT length = 0;
476 HOST_WIDE_INT offset = 0;
477 unsigned HOST_WIDE_INT known_align, desired_align;
478 bool overlap = false;
481 unsigned char *data, *chk;
482 VEC(constructor_elt,gc) *v = NULL;
484 tree type = unsigned_char_type_node;
487 /* Obtain the size of the union and check if there are any overlapping
489 for (s = head; s; s = s->next)
491 HOST_WIDE_INT slen = s->offset + s->length;
494 if (s->offset < offset)
498 length = length < slen ? slen : length;
504 /* Now absorb all the initializer data into a single vector,
505 whilst checking for overlapping, unequal values. */
506 data = (unsigned char*)gfc_getmem ((size_t)length);
507 chk = (unsigned char*)gfc_getmem ((size_t)length);
509 /* TODO - change this when default initialization is implemented. */
510 memset (data, '\0', (size_t)length);
511 memset (chk, '\0', (size_t)length);
512 for (s = head; s; s = s->next)
514 gfc_merge_initializers (s->sym->ts, s->sym->value,
519 for (i = 0; i < length; i++)
520 CONSTRUCTOR_APPEND_ELT (v, NULL, build_int_cst (type, data[i]));
525 /* Build a char[length] array to hold the initializers. Much of what
526 follows is borrowed from build_field, above. */
528 tmp = build_int_cst (gfc_array_index_type, length - 1);
529 tmp = build_range_type (gfc_array_index_type,
530 gfc_index_zero_node, tmp);
531 tmp = build_array_type (type, tmp);
532 field = build_decl (gfc_current_locus.lb->location,
533 FIELD_DECL, NULL_TREE, tmp);
535 known_align = BIGGEST_ALIGNMENT;
537 desired_align = update_alignment_for_field (rli, field, known_align);
538 if (desired_align > known_align)
539 DECL_PACKED (field) = 1;
541 DECL_FIELD_CONTEXT (field) = union_type;
542 DECL_FIELD_OFFSET (field) = size_int (0);
543 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
544 SET_DECL_OFFSET_ALIGN (field, known_align);
546 rli->offset = size_binop (MAX_EXPR, rli->offset,
547 size_binop (PLUS_EXPR,
548 DECL_FIELD_OFFSET (field),
549 DECL_SIZE_UNIT (field)));
551 init = build_constructor (TREE_TYPE (field), v);
552 TREE_CONSTANT (init) = 1;
556 for (s = head; s; s = s->next)
558 if (s->sym->value == NULL)
561 gfc_free_expr (s->sym->value);
562 s->sym->value = NULL;
569 /* Declare memory for the common block or local equivalence, and create
570 backend declarations for all of the elements. */
573 create_common (gfc_common_head *com, segment_info *head, bool saw_equiv)
575 segment_info *s, *next_s;
579 tree field_init = NULL_TREE;
580 record_layout_info rli;
582 bool is_init = false;
583 bool is_saved = false;
585 /* Declare the variables inside the common block.
586 If the current common block contains any equivalence object, then
587 make a UNION_TYPE node, otherwise RECORD_TYPE. This will let the
588 alias analyzer work well when there is no address overlapping for
589 common variables in the current common block. */
591 union_type = make_node (UNION_TYPE);
593 union_type = make_node (RECORD_TYPE);
595 rli = start_record_layout (union_type);
596 field_link = &TYPE_FIELDS (union_type);
598 /* Check for overlapping initializers and replace them with a single,
599 artificial field that contains all the data. */
601 field = get_init_field (head, union_type, &field_init, rli);
605 if (field != NULL_TREE)
609 field_link = &TREE_CHAIN (field);
612 for (s = head; s; s = s->next)
614 build_field (s, union_type, rli);
616 /* Link the field into the type. */
617 *field_link = s->field;
618 field_link = &TREE_CHAIN (s->field);
620 /* Has initial value. */
624 /* Has SAVE attribute. */
625 if (s->sym->attr.save)
629 finish_record_layout (rli, true);
632 decl = build_common_decl (com, union_type, is_init);
634 decl = build_equiv_decl (union_type, is_init, is_saved);
639 HOST_WIDE_INT offset = 0;
640 VEC(constructor_elt,gc) *v = NULL;
642 if (field != NULL_TREE && field_init != NULL_TREE)
643 CONSTRUCTOR_APPEND_ELT (v, field, field_init);
645 for (s = head; s; s = s->next)
649 /* Add the initializer for this field. */
650 tmp = gfc_conv_initializer (s->sym->value, &s->sym->ts,
651 TREE_TYPE (s->field), s->sym->attr.dimension,
652 s->sym->attr.pointer || s->sym->attr.allocatable);
654 CONSTRUCTOR_APPEND_ELT (v, s->field, tmp);
655 offset = s->offset + s->length;
659 gcc_assert (!VEC_empty (constructor_elt, v));
660 ctor = build_constructor (union_type, v);
661 TREE_CONSTANT (ctor) = 1;
662 TREE_STATIC (ctor) = 1;
663 DECL_INITIAL (decl) = ctor;
665 #ifdef ENABLE_CHECKING
668 unsigned HOST_WIDE_INT idx;
669 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), idx, field, value)
670 gcc_assert (TREE_CODE (field) == FIELD_DECL);
675 /* Build component reference for each variable. */
676 for (s = head; s; s = next_s)
680 var_decl = build_decl (s->sym->declared_at.lb->location,
681 VAR_DECL, DECL_NAME (s->field),
682 TREE_TYPE (s->field));
683 TREE_PUBLIC (var_decl) = TREE_PUBLIC (decl);
684 TREE_STATIC (var_decl) = TREE_STATIC (decl);
685 TREE_USED (var_decl) = TREE_USED (decl);
686 if (s->sym->attr.use_assoc)
687 DECL_IGNORED_P (var_decl) = 1;
688 if (s->sym->attr.target)
689 TREE_ADDRESSABLE (var_decl) = 1;
690 /* This is a fake variable just for debugging purposes. */
691 TREE_ASM_WRITTEN (var_decl) = 1;
693 /* To preserve identifier names in COMMON, chain to procedure
694 scope unless at top level in a module definition. */
696 && s->sym->ns->proc_name
697 && s->sym->ns->proc_name->attr.flavor == FL_MODULE)
698 var_decl = pushdecl_top_level (var_decl);
700 gfc_add_decl_to_function (var_decl);
702 SET_DECL_VALUE_EXPR (var_decl,
703 fold_build3 (COMPONENT_REF, TREE_TYPE (s->field),
704 decl, s->field, NULL_TREE));
705 DECL_HAS_VALUE_EXPR_P (var_decl) = 1;
706 GFC_DECL_COMMON_OR_EQUIV (var_decl) = 1;
708 if (s->sym->attr.assign)
710 gfc_allocate_lang_decl (var_decl);
711 GFC_DECL_ASSIGN (var_decl) = 1;
712 GFC_DECL_STRING_LEN (var_decl) = GFC_DECL_STRING_LEN (s->field);
713 GFC_DECL_ASSIGN_ADDR (var_decl) = GFC_DECL_ASSIGN_ADDR (s->field);
716 s->sym->backend_decl = var_decl;
724 /* Given a symbol, find it in the current segment list. Returns NULL if
727 static segment_info *
728 find_segment_info (gfc_symbol *symbol)
732 for (n = current_segment; n; n = n->next)
734 if (n->sym == symbol)
742 /* Given an expression node, make sure it is a constant integer and return
746 get_mpz (gfc_expr *e)
749 if (e->expr_type != EXPR_CONSTANT)
750 gfc_internal_error ("get_mpz(): Not an integer constant");
752 return &e->value.integer;
756 /* Given an array specification and an array reference, figure out the
757 array element number (zero based). Bounds and elements are guaranteed
758 to be constants. If something goes wrong we generate an error and
762 element_number (gfc_array_ref *ar)
764 mpz_t multiplier, offset, extent, n;
766 HOST_WIDE_INT i, rank;
770 mpz_init_set_ui (multiplier, 1);
771 mpz_init_set_ui (offset, 0);
775 for (i = 0; i < rank; i++)
777 if (ar->dimen_type[i] != DIMEN_ELEMENT)
778 gfc_internal_error ("element_number(): Bad dimension type");
780 mpz_sub (n, *get_mpz (ar->start[i]), *get_mpz (as->lower[i]));
782 mpz_mul (n, n, multiplier);
783 mpz_add (offset, offset, n);
785 mpz_sub (extent, *get_mpz (as->upper[i]), *get_mpz (as->lower[i]));
786 mpz_add_ui (extent, extent, 1);
788 if (mpz_sgn (extent) < 0)
789 mpz_set_ui (extent, 0);
791 mpz_mul (multiplier, multiplier, extent);
794 i = mpz_get_ui (offset);
796 mpz_clear (multiplier);
805 /* Given a single element of an equivalence list, figure out the offset
806 from the base symbol. For simple variables or full arrays, this is
807 simply zero. For an array element we have to calculate the array
808 element number and multiply by the element size. For a substring we
809 have to calculate the further reference. */
812 calculate_offset (gfc_expr *e)
814 HOST_WIDE_INT n, element_size, offset;
815 gfc_typespec *element_type;
819 element_type = &e->symtree->n.sym->ts;
821 for (reference = e->ref; reference; reference = reference->next)
822 switch (reference->type)
825 switch (reference->u.ar.type)
831 n = element_number (&reference->u.ar);
832 if (element_type->type == BT_CHARACTER)
833 gfc_conv_const_charlen (element_type->u.cl);
835 int_size_in_bytes (gfc_typenode_for_spec (element_type));
836 offset += n * element_size;
840 gfc_error ("Bad array reference at %L", &e->where);
844 if (reference->u.ss.start != NULL)
845 offset += mpz_get_ui (*get_mpz (reference->u.ss.start)) - 1;
848 gfc_error ("Illegal reference type at %L as EQUIVALENCE object",
855 /* Add a new segment_info structure to the current segment. eq1 is already
856 in the list, eq2 is not. */
859 new_condition (segment_info *v, gfc_equiv *eq1, gfc_equiv *eq2)
861 HOST_WIDE_INT offset1, offset2;
864 offset1 = calculate_offset (eq1->expr);
865 offset2 = calculate_offset (eq2->expr);
867 a = get_segment_info (eq2->expr->symtree->n.sym,
868 v->offset + offset1 - offset2);
870 current_segment = add_segments (current_segment, a);
874 /* Given two equivalence structures that are both already in the list, make
875 sure that this new condition is not violated, generating an error if it
879 confirm_condition (segment_info *s1, gfc_equiv *eq1, segment_info *s2,
882 HOST_WIDE_INT offset1, offset2;
884 offset1 = calculate_offset (eq1->expr);
885 offset2 = calculate_offset (eq2->expr);
887 if (s1->offset + offset1 != s2->offset + offset2)
888 gfc_error ("Inconsistent equivalence rules involving '%s' at %L and "
889 "'%s' at %L", s1->sym->name, &s1->sym->declared_at,
890 s2->sym->name, &s2->sym->declared_at);
894 /* Process a new equivalence condition. eq1 is know to be in segment f.
895 If eq2 is also present then confirm that the condition holds.
896 Otherwise add a new variable to the segment list. */
899 add_condition (segment_info *f, gfc_equiv *eq1, gfc_equiv *eq2)
903 n = find_segment_info (eq2->expr->symtree->n.sym);
906 new_condition (f, eq1, eq2);
908 confirm_condition (f, eq1, n, eq2);
912 /* Given a segment element, search through the equivalence lists for unused
913 conditions that involve the symbol. Add these rules to the segment. */
916 find_equivalence (segment_info *n)
918 gfc_equiv *e1, *e2, *eq;
923 for (e1 = n->sym->ns->equiv; e1; e1 = e1->next)
927 /* Search the equivalence list, including the root (first) element
928 for the symbol that owns the segment. */
929 for (e2 = e1; e2; e2 = e2->eq)
931 if (!e2->used && e2->expr->symtree->n.sym == n->sym)
938 /* Go to the next root element. */
944 /* Now traverse the equivalence list matching the offsets. */
945 for (e2 = e1; e2; e2 = e2->eq)
947 if (!e2->used && e2 != eq)
949 add_condition (n, eq, e2);
959 /* Add all symbols equivalenced within a segment. We need to scan the
960 segment list multiple times to include indirect equivalences. Since
961 a new segment_info can inserted at the beginning of the segment list,
962 depending on its offset, we have to force a final pass through the
963 loop by demanding that completion sees a pass with no matches; i.e.,
964 all symbols with equiv_built set and no new equivalences found. */
967 add_equivalences (bool *saw_equiv)
977 for (f = current_segment; f; f = f->next)
979 if (!f->sym->equiv_built)
981 f->sym->equiv_built = 1;
982 seen_one = find_equivalence (f);
992 /* Add a copy of this segment list to the namespace. */
993 copy_equiv_list_to_ns (current_segment);
997 /* Returns the offset necessary to properly align the current equivalence.
998 Sets *palign to the required alignment. */
1000 static HOST_WIDE_INT
1001 align_segment (unsigned HOST_WIDE_INT *palign)
1004 unsigned HOST_WIDE_INT offset;
1005 unsigned HOST_WIDE_INT max_align;
1006 unsigned HOST_WIDE_INT this_align;
1007 unsigned HOST_WIDE_INT this_offset;
1011 for (s = current_segment; s; s = s->next)
1013 this_align = TYPE_ALIGN_UNIT (s->field);
1014 if (s->offset & (this_align - 1))
1016 /* Field is misaligned. */
1017 this_offset = this_align - ((s->offset + offset) & (this_align - 1));
1018 if (this_offset & (max_align - 1))
1020 /* Aligning this field would misalign a previous field. */
1021 gfc_error ("The equivalence set for variable '%s' "
1022 "declared at %L violates alignment requirements",
1023 s->sym->name, &s->sym->declared_at);
1025 offset += this_offset;
1027 max_align = this_align;
1030 *palign = max_align;
1035 /* Adjust segment offsets by the given amount. */
1038 apply_segment_offset (segment_info *s, HOST_WIDE_INT offset)
1040 for (; s; s = s->next)
1041 s->offset += offset;
1045 /* Lay out a symbol in a common block. If the symbol has already been seen
1046 then check the location is consistent. Otherwise create segments
1047 for that symbol and all the symbols equivalenced with it. */
1049 /* Translate a single common block. */
1052 translate_common (gfc_common_head *common, gfc_symbol *var_list)
1056 segment_info *common_segment;
1057 HOST_WIDE_INT offset;
1058 HOST_WIDE_INT current_offset;
1059 unsigned HOST_WIDE_INT align;
1060 unsigned HOST_WIDE_INT max_align;
1063 common_segment = NULL;
1070 /* Add symbols to the segment. */
1071 for (sym = var_list; sym; sym = sym->common_next)
1073 current_segment = common_segment;
1074 s = find_segment_info (sym);
1076 /* Symbol has already been added via an equivalence. Multiple
1077 use associations of the same common block result in equiv_built
1078 being set but no information about the symbol in the segment. */
1079 if (s && sym->equiv_built)
1081 /* Ensure the current location is properly aligned. */
1082 align = TYPE_ALIGN_UNIT (s->field);
1083 current_offset = (current_offset + align - 1) &~ (align - 1);
1085 /* Verify that it ended up where we expect it. */
1086 if (s->offset != current_offset)
1088 gfc_error ("Equivalence for '%s' does not match ordering of "
1089 "COMMON '%s' at %L", sym->name,
1090 common->name, &common->where);
1095 /* A symbol we haven't seen before. */
1096 s = current_segment = get_segment_info (sym, current_offset);
1098 /* Add all objects directly or indirectly equivalenced with this
1100 add_equivalences (&saw_equiv);
1102 if (current_segment->offset < 0)
1103 gfc_error ("The equivalence set for '%s' cause an invalid "
1104 "extension to COMMON '%s' at %L", sym->name,
1105 common->name, &common->where);
1107 if (gfc_option.flag_align_commons)
1108 offset = align_segment (&align);
1110 if (offset & (max_align - 1))
1112 /* The required offset conflicts with previous alignment
1113 requirements. Insert padding immediately before this
1115 if (gfc_option.warn_align_commons)
1117 if (strcmp (common->name, BLANK_COMMON_NAME))
1118 gfc_warning ("Padding of %d bytes required before '%s' in "
1119 "COMMON '%s' at %L; reorder elements or use "
1120 "-fno-align-commons", (int)offset,
1121 s->sym->name, common->name, &common->where);
1123 gfc_warning ("Padding of %d bytes required before '%s' in "
1124 "COMMON at %L; reorder elements or use "
1125 "-fno-align-commons", (int)offset,
1126 s->sym->name, &common->where);
1130 /* Apply the offset to the new segments. */
1131 apply_segment_offset (current_segment, offset);
1132 current_offset += offset;
1133 if (max_align < align)
1136 /* Add the new segments to the common block. */
1137 common_segment = add_segments (common_segment, current_segment);
1140 /* The offset of the next common variable. */
1141 current_offset += s->length;
1144 if (common_segment == NULL)
1146 gfc_error ("COMMON '%s' at %L does not exist",
1147 common->name, &common->where);
1151 if (common_segment->offset != 0 && gfc_option.warn_align_commons)
1153 if (strcmp (common->name, BLANK_COMMON_NAME))
1154 gfc_warning ("COMMON '%s' at %L requires %d bytes of padding at start; "
1155 "reorder elements or use -fno-align-commons",
1156 common->name, &common->where, (int)common_segment->offset);
1158 gfc_warning ("COMMON at %L requires %d bytes of padding at start; "
1159 "reorder elements or use -fno-align-commons",
1160 &common->where, (int)common_segment->offset);
1163 create_common (common, common_segment, saw_equiv);
1167 /* Create a new block for each merged equivalence list. */
1170 finish_equivalences (gfc_namespace *ns)
1174 gfc_common_head * c;
1175 HOST_WIDE_INT offset;
1176 unsigned HOST_WIDE_INT align;
1179 for (z = ns->equiv; z; z = z->next)
1180 for (y = z->eq; y; y = y->eq)
1184 sym = z->expr->symtree->n.sym;
1185 current_segment = get_segment_info (sym, 0);
1187 /* All objects directly or indirectly equivalenced with this
1189 add_equivalences (&dummy);
1191 /* Align the block. */
1192 offset = align_segment (&align);
1194 /* Ensure all offsets are positive. */
1195 offset -= current_segment->offset & ~(align - 1);
1197 apply_segment_offset (current_segment, offset);
1199 /* Create the decl. If this is a module equivalence, it has a
1200 unique name, pointed to by z->module. This is written to a
1201 gfc_common_header to push create_common into using
1202 build_common_decl, so that the equivalence appears as an
1203 external symbol. Otherwise, a local declaration is built using
1204 build_equiv_decl. */
1207 c = gfc_get_common_head ();
1208 /* We've lost the real location, so use the location of the
1209 enclosing procedure. */
1210 c->where = ns->proc_name->declared_at;
1211 strcpy (c->name, z->module);
1216 create_common (c, current_segment, true);
1222 /* Work function for translating a named common block. */
1225 named_common (gfc_symtree *st)
1227 translate_common (st->n.common, st->n.common->head);
1231 /* Translate the common blocks in a namespace. Unlike other variables,
1232 these have to be created before code, because the backend_decl depends
1233 on the rest of the common block. */
1236 gfc_trans_common (gfc_namespace *ns)
1240 /* Translate the blank common block. */
1241 if (ns->blank_common.head != NULL)
1243 c = gfc_get_common_head ();
1244 c->where = ns->blank_common.head->common_head->where;
1245 strcpy (c->name, BLANK_COMMON_NAME);
1246 translate_common (c, ns->blank_common.head);
1249 /* Translate all named common blocks. */
1250 gfc_traverse_symtree (ns->common_root, named_common);
1252 /* Translate local equivalence. */
1253 finish_equivalences (ns);
1255 /* Commit the newly created symbols for common blocks and module
1257 gfc_commit_symbols ();