1 /* Common block and equivalence list handling
2 Copyright (C) 2000, 2003, 2004, 2005, 2006, 2007
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 2, 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 COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
23 /* The core algorithm is based on Andy Vaught's g95 tree. Also the
24 way to build UNION_TYPE is borrowed from Richard Henderson.
26 Transform common blocks. An integral part of this is processing
27 equivalence variables. Equivalenced variables that are not in a
28 common block end up in a private block of their own.
30 Each common block or local equivalence list is declared as a union.
31 Variables within the block are represented as a field within the
32 block with the proper offset.
34 So if two variables are equivalenced, they just point to a common
37 Mathematically, laying out an equivalence block is equivalent to
38 solving a linear system of equations. The matrix is usually a
39 sparse matrix in which each row contains all zero elements except
40 for a +1 and a -1, a sort of a generalized Vandermonde matrix. The
41 matrix is usually block diagonal. The system can be
42 overdetermined, underdetermined or have a unique solution. If the
43 system is inconsistent, the program is not standard conforming.
44 The solution vector is integral, since all of the pivots are +1 or -1.
46 How we lay out an equivalence block is a little less complicated.
47 In an equivalence list with n elements, there are n-1 conditions to
48 be satisfied. The conditions partition the variables into what we
49 will call segments. If A and B are equivalenced then A and B are
50 in the same segment. If B and C are equivalenced as well, then A,
51 B and C are in a segment and so on. Each segment is a block of
52 memory that has one or more variables equivalenced in some way. A
53 common block is made up of a series of segments that are joined one
54 after the other. In the linear system, a segment is a block
57 To lay out a segment we first start with some variable and
58 determine its length. The first variable is assumed to start at
59 offset one and extends to however long it is. We then traverse the
60 list of equivalences to find an unused condition that involves at
61 least one of the variables currently in the segment.
63 Each equivalence condition amounts to the condition B+b=C+c where B
64 and C are the offsets of the B and C variables, and b and c are
65 constants which are nonzero for array elements, substrings or
66 structure components. So for
68 EQUIVALENCE(B(2), C(3))
70 B + 2*size of B's elements = C + 3*size of C's elements.
72 If B and C are known we check to see if the condition already
73 holds. If B is known we can solve for C. Since we know the length
74 of C, we can see if the minimum and maximum extents of the segment
75 are affected. Eventually, we make a full pass through the
76 equivalence list without finding any new conditions and the segment
79 At this point, the segment is added to the current common block.
80 Since we know the minimum extent of the segment, everything in the
81 segment is translated to its position in the common block. The
82 usual case here is that there are no equivalence statements and the
83 common block is series of segments with one variable each, which is
84 a diagonal matrix in the matrix formulation.
86 Each segment is described by a chain of segment_info structures. Each
87 segment_info structure describes the extents of a single variable within
88 the segment. This list is maintained in the order the elements are
89 positioned withing the segment. If two elements have the same starting
90 offset the smaller will come first. If they also have the same size their
91 ordering is undefined.
93 Once all common blocks have been created, the list of equivalences
94 is examined for still-unused equivalence conditions. We create a
95 block for each merged equivalence list. */
99 #include "coretypes.h"
105 #include "gfortran.h"
107 #include "trans-types.h"
108 #include "trans-const.h"
109 #include "target-memory.h"
112 /* Holds a single variable in an equivalence set. */
113 typedef struct segment_info
116 HOST_WIDE_INT offset;
117 HOST_WIDE_INT length;
118 /* This will contain the field type until the field is created. */
120 struct segment_info *next;
123 static segment_info * current_segment;
124 static gfc_namespace *gfc_common_ns = NULL;
127 /* Make a segment_info based on a symbol. */
129 static segment_info *
130 get_segment_info (gfc_symbol * sym, HOST_WIDE_INT offset)
134 /* Make sure we've got the character length. */
135 if (sym->ts.type == BT_CHARACTER)
136 gfc_conv_const_charlen (sym->ts.cl);
138 /* Create the segment_info and fill it in. */
139 s = (segment_info *) gfc_getmem (sizeof (segment_info));
141 /* We will use this type when building the segment aggregate type. */
142 s->field = gfc_sym_type (sym);
143 s->length = int_size_in_bytes (s->field);
150 /* Add a copy of a segment list to the namespace. This is specifically for
151 equivalence segments, so that dependency checking can be done on
152 equivalence group members. */
155 copy_equiv_list_to_ns (segment_info *c)
161 l = (gfc_equiv_list *) gfc_getmem (sizeof (gfc_equiv_list));
163 l->next = c->sym->ns->equiv_lists;
164 c->sym->ns->equiv_lists = l;
166 for (f = c; f; f = f->next)
168 s = (gfc_equiv_info *) gfc_getmem (sizeof (gfc_equiv_info));
172 s->offset = f->offset;
173 s->length = f->length;
178 /* Add combine segment V and segment LIST. */
180 static segment_info *
181 add_segments (segment_info *list, segment_info *v)
192 /* Find the location of the new element. */
195 if (v->offset < s->offset)
197 if (v->offset == s->offset
198 && v->length <= s->length)
205 /* Insert the new element in between p and s. */
220 /* Construct mangled common block name from symbol name. */
223 gfc_sym_mangled_common_id (const char *name)
226 char mangled_name[GFC_MAX_MANGLED_SYMBOL_LEN + 1];
228 if (strcmp (name, BLANK_COMMON_NAME) == 0)
229 return get_identifier (name);
231 if (gfc_option.flag_underscoring)
233 has_underscore = strchr (name, '_') != 0;
234 if (gfc_option.flag_second_underscore && has_underscore)
235 snprintf (mangled_name, sizeof mangled_name, "%s__", name);
237 snprintf (mangled_name, sizeof mangled_name, "%s_", name);
239 return get_identifier (mangled_name);
242 return get_identifier (name);
246 /* Build a field declaration for a common variable or a local equivalence
250 build_field (segment_info *h, tree union_type, record_layout_info rli)
254 HOST_WIDE_INT offset = h->offset;
255 unsigned HOST_WIDE_INT desired_align, known_align;
257 name = get_identifier (h->sym->name);
258 field = build_decl (FIELD_DECL, name, h->field);
259 gfc_set_decl_location (field, &h->sym->declared_at);
260 known_align = (offset & -offset) * BITS_PER_UNIT;
261 if (known_align == 0 || known_align > BIGGEST_ALIGNMENT)
262 known_align = BIGGEST_ALIGNMENT;
264 desired_align = update_alignment_for_field (rli, field, known_align);
265 if (desired_align > known_align)
266 DECL_PACKED (field) = 1;
268 DECL_FIELD_CONTEXT (field) = union_type;
269 DECL_FIELD_OFFSET (field) = size_int (offset);
270 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
271 SET_DECL_OFFSET_ALIGN (field, known_align);
273 rli->offset = size_binop (MAX_EXPR, rli->offset,
274 size_binop (PLUS_EXPR,
275 DECL_FIELD_OFFSET (field),
276 DECL_SIZE_UNIT (field)));
277 /* If this field is assigned to a label, we create another two variables.
278 One will hold the address of target label or format label. The other will
279 hold the length of format label string. */
280 if (h->sym->attr.assign)
285 gfc_allocate_lang_decl (field);
286 GFC_DECL_ASSIGN (field) = 1;
287 len = gfc_create_var_np (gfc_charlen_type_node,h->sym->name);
288 addr = gfc_create_var_np (pvoid_type_node, h->sym->name);
289 TREE_STATIC (len) = 1;
290 TREE_STATIC (addr) = 1;
291 DECL_INITIAL (len) = build_int_cst (NULL_TREE, -2);
292 gfc_set_decl_location (len, &h->sym->declared_at);
293 gfc_set_decl_location (addr, &h->sym->declared_at);
294 GFC_DECL_STRING_LEN (field) = pushdecl_top_level (len);
295 GFC_DECL_ASSIGN_ADDR (field) = pushdecl_top_level (addr);
302 /* Get storage for local equivalence. */
305 build_equiv_decl (tree union_type, bool is_init, bool is_saved)
309 static int serial = 0;
313 decl = gfc_create_var (union_type, "equiv");
314 TREE_STATIC (decl) = 1;
315 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
319 snprintf (name, sizeof (name), "equiv.%d", serial++);
320 decl = build_decl (VAR_DECL, get_identifier (name), union_type);
321 DECL_ARTIFICIAL (decl) = 1;
322 DECL_IGNORED_P (decl) = 1;
324 if (!gfc_can_put_var_on_stack (DECL_SIZE_UNIT (decl))
326 TREE_STATIC (decl) = 1;
328 TREE_ADDRESSABLE (decl) = 1;
329 TREE_USED (decl) = 1;
330 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
332 /* The source location has been lost, and doesn't really matter.
333 We need to set it to something though. */
334 gfc_set_decl_location (decl, &gfc_current_locus);
336 gfc_add_decl_to_function (decl);
342 /* Get storage for common block. */
345 build_common_decl (gfc_common_head *com, tree union_type, bool is_init)
347 gfc_symbol *common_sym;
350 /* Create a namespace to store symbols for common blocks. */
351 if (gfc_common_ns == NULL)
352 gfc_common_ns = gfc_get_namespace (NULL, 0);
354 gfc_get_symbol (com->name, gfc_common_ns, &common_sym);
355 decl = common_sym->backend_decl;
357 /* Update the size of this common block as needed. */
358 if (decl != NULL_TREE)
360 tree size = TYPE_SIZE_UNIT (union_type);
361 if (tree_int_cst_lt (DECL_SIZE_UNIT (decl), size))
363 /* Named common blocks of the same name shall be of the same size
364 in all scoping units of a program in which they appear, but
365 blank common blocks may be of different sizes. */
366 if (strcmp (com->name, BLANK_COMMON_NAME))
367 gfc_warning ("Named COMMON block '%s' at %L shall be of the "
368 "same size", com->name, &com->where);
369 DECL_SIZE_UNIT (decl) = size;
373 /* If this common block has been declared in a previous program unit,
374 and either it is already initialized or there is no new initialization
375 for it, just return. */
376 if ((decl != NULL_TREE) && (!is_init || DECL_INITIAL (decl)))
379 /* If there is no backend_decl for the common block, build it. */
380 if (decl == NULL_TREE)
382 decl = build_decl (VAR_DECL, get_identifier (com->name), union_type);
383 SET_DECL_ASSEMBLER_NAME (decl, gfc_sym_mangled_common_id (com->name));
384 TREE_PUBLIC (decl) = 1;
385 TREE_STATIC (decl) = 1;
386 DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
387 DECL_USER_ALIGN (decl) = 0;
388 GFC_DECL_COMMON_OR_EQUIV (decl) = 1;
390 gfc_set_decl_location (decl, &com->where);
392 if (com->threadprivate)
393 DECL_TLS_MODEL (decl) = decl_default_tls_model (decl);
395 /* Place the back end declaration for this common block in
396 GLOBAL_BINDING_LEVEL. */
397 common_sym->backend_decl = pushdecl_top_level (decl);
400 /* Has no initial values. */
403 DECL_INITIAL (decl) = NULL_TREE;
404 DECL_COMMON (decl) = 1;
405 DECL_DEFER_OUTPUT (decl) = 1;
409 DECL_INITIAL (decl) = error_mark_node;
410 DECL_COMMON (decl) = 0;
411 DECL_DEFER_OUTPUT (decl) = 0;
417 /* Return a field that is the size of the union, if an equivalence has
418 overlapping initializers. Merge the initializers into a single
419 initializer for this new field, then free the old ones. */
422 get_init_field (segment_info *head, tree union_type, tree *field_init,
423 record_layout_info rli)
426 HOST_WIDE_INT length = 0;
427 HOST_WIDE_INT offset = 0;
428 unsigned HOST_WIDE_INT known_align, desired_align;
429 bool overlap = false;
432 unsigned char *data, *chk;
433 VEC(constructor_elt,gc) *v = NULL;
435 tree type = unsigned_char_type_node;
438 /* Obtain the size of the union and check if there are any overlapping
440 for (s = head; s; s = s->next)
442 HOST_WIDE_INT slen = s->offset + s->length;
445 if (s->offset < offset)
449 length = length < slen ? slen : length;
455 /* Now absorb all the initializer data into a single vector,
456 whilst checking for overlapping, unequal values. */
457 data = (unsigned char*)gfc_getmem ((size_t)length);
458 chk = (unsigned char*)gfc_getmem ((size_t)length);
460 /* TODO - change this when default initialization is implemented. */
461 memset (data, '\0', (size_t)length);
462 memset (chk, '\0', (size_t)length);
463 for (s = head; s; s = s->next)
465 gfc_merge_initializers (s->sym->ts, s->sym->value,
470 for (i = 0; i < length; i++)
471 CONSTRUCTOR_APPEND_ELT (v, NULL, build_int_cst (type, data[i]));
476 /* Build a char[length] array to hold the initializers. Much of what
477 follows is borrowed from build_field, above. */
479 tmp = build_int_cst (gfc_array_index_type, length - 1);
480 tmp = build_range_type (gfc_array_index_type,
481 gfc_index_zero_node, tmp);
482 tmp = build_array_type (type, tmp);
483 field = build_decl (FIELD_DECL, NULL_TREE, tmp);
484 gfc_set_decl_location (field, &gfc_current_locus);
486 known_align = BIGGEST_ALIGNMENT;
488 desired_align = update_alignment_for_field (rli, field, known_align);
489 if (desired_align > known_align)
490 DECL_PACKED (field) = 1;
492 DECL_FIELD_CONTEXT (field) = union_type;
493 DECL_FIELD_OFFSET (field) = size_int (0);
494 DECL_FIELD_BIT_OFFSET (field) = bitsize_zero_node;
495 SET_DECL_OFFSET_ALIGN (field, known_align);
497 rli->offset = size_binop (MAX_EXPR, rli->offset,
498 size_binop (PLUS_EXPR,
499 DECL_FIELD_OFFSET (field),
500 DECL_SIZE_UNIT (field)));
502 init = build_constructor (TREE_TYPE (field), v);
503 TREE_CONSTANT (init) = 1;
504 TREE_INVARIANT (init) = 1;
508 for (s = head; s; s = s->next)
510 if (s->sym->value == NULL)
513 gfc_free_expr (s->sym->value);
514 s->sym->value = NULL;
521 /* Declare memory for the common block or local equivalence, and create
522 backend declarations for all of the elements. */
525 create_common (gfc_common_head *com, segment_info *head, bool saw_equiv)
527 segment_info *s, *next_s;
532 record_layout_info rli;
534 bool is_init = false;
535 bool is_saved = false;
537 /* Declare the variables inside the common block.
538 If the current common block contains any equivalence object, then
539 make a UNION_TYPE node, otherwise RECORD_TYPE. This will let the
540 alias analyzer work well when there is no address overlapping for
541 common variables in the current common block. */
543 union_type = make_node (UNION_TYPE);
545 union_type = make_node (RECORD_TYPE);
547 rli = start_record_layout (union_type);
548 field_link = &TYPE_FIELDS (union_type);
550 /* Check for overlapping initializers and replace them with a single,
551 artificial field that contains all the data. */
553 field = get_init_field (head, union_type, &field_init, rli);
557 if (field != NULL_TREE)
561 field_link = &TREE_CHAIN (field);
564 for (s = head; s; s = s->next)
566 build_field (s, union_type, rli);
568 /* Link the field into the type. */
569 *field_link = s->field;
570 field_link = &TREE_CHAIN (s->field);
572 /* Has initial value. */
576 /* Has SAVE attribute. */
577 if (s->sym->attr.save)
581 finish_record_layout (rli, true);
584 decl = build_common_decl (com, union_type, is_init);
586 decl = build_equiv_decl (union_type, is_init, is_saved);
591 HOST_WIDE_INT offset = 0;
592 VEC(constructor_elt,gc) *v = NULL;
594 if (field != NULL_TREE && field_init != NULL_TREE)
595 CONSTRUCTOR_APPEND_ELT (v, field, field_init);
597 for (s = head; s; s = s->next)
601 /* Add the initializer for this field. */
602 tmp = gfc_conv_initializer (s->sym->value, &s->sym->ts,
603 TREE_TYPE (s->field), s->sym->attr.dimension,
604 s->sym->attr.pointer || s->sym->attr.allocatable);
606 CONSTRUCTOR_APPEND_ELT (v, s->field, tmp);
607 offset = s->offset + s->length;
611 gcc_assert (!VEC_empty (constructor_elt, v));
612 ctor = build_constructor (union_type, v);
613 TREE_CONSTANT (ctor) = 1;
614 TREE_INVARIANT (ctor) = 1;
615 TREE_STATIC (ctor) = 1;
616 DECL_INITIAL (decl) = ctor;
618 #ifdef ENABLE_CHECKING
621 unsigned HOST_WIDE_INT idx;
622 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), idx, field, value)
623 gcc_assert (TREE_CODE (field) == FIELD_DECL);
628 /* Build component reference for each variable. */
629 for (s = head; s; s = next_s)
633 var_decl = build_decl (VAR_DECL, DECL_NAME (s->field),
634 TREE_TYPE (s->field));
635 gfc_set_decl_location (var_decl, &s->sym->declared_at);
636 TREE_PUBLIC (var_decl) = TREE_PUBLIC (decl);
637 TREE_STATIC (var_decl) = TREE_STATIC (decl);
638 TREE_USED (var_decl) = TREE_USED (decl);
639 if (s->sym->attr.target)
640 TREE_ADDRESSABLE (var_decl) = 1;
641 /* This is a fake variable just for debugging purposes. */
642 TREE_ASM_WRITTEN (var_decl) = 1;
645 var_decl = pushdecl_top_level (var_decl);
647 gfc_add_decl_to_function (var_decl);
649 SET_DECL_VALUE_EXPR (var_decl,
650 build3 (COMPONENT_REF, TREE_TYPE (s->field),
651 decl, s->field, NULL_TREE));
652 DECL_HAS_VALUE_EXPR_P (var_decl) = 1;
653 GFC_DECL_COMMON_OR_EQUIV (var_decl) = 1;
655 if (s->sym->attr.assign)
657 gfc_allocate_lang_decl (var_decl);
658 GFC_DECL_ASSIGN (var_decl) = 1;
659 GFC_DECL_STRING_LEN (var_decl) = GFC_DECL_STRING_LEN (s->field);
660 GFC_DECL_ASSIGN_ADDR (var_decl) = GFC_DECL_ASSIGN_ADDR (s->field);
663 s->sym->backend_decl = var_decl;
671 /* Given a symbol, find it in the current segment list. Returns NULL if
674 static segment_info *
675 find_segment_info (gfc_symbol *symbol)
679 for (n = current_segment; n; n = n->next)
681 if (n->sym == symbol)
689 /* Given an expression node, make sure it is a constant integer and return
693 get_mpz (gfc_expr *e)
696 if (e->expr_type != EXPR_CONSTANT)
697 gfc_internal_error ("get_mpz(): Not an integer constant");
699 return &e->value.integer;
703 /* Given an array specification and an array reference, figure out the
704 array element number (zero based). Bounds and elements are guaranteed
705 to be constants. If something goes wrong we generate an error and
709 element_number (gfc_array_ref *ar)
711 mpz_t multiplier, offset, extent, n;
713 HOST_WIDE_INT i, rank;
717 mpz_init_set_ui (multiplier, 1);
718 mpz_init_set_ui (offset, 0);
722 for (i = 0; i < rank; i++)
724 if (ar->dimen_type[i] != DIMEN_ELEMENT)
725 gfc_internal_error ("element_number(): Bad dimension type");
727 mpz_sub (n, *get_mpz (ar->start[i]), *get_mpz (as->lower[i]));
729 mpz_mul (n, n, multiplier);
730 mpz_add (offset, offset, n);
732 mpz_sub (extent, *get_mpz (as->upper[i]), *get_mpz (as->lower[i]));
733 mpz_add_ui (extent, extent, 1);
735 if (mpz_sgn (extent) < 0)
736 mpz_set_ui (extent, 0);
738 mpz_mul (multiplier, multiplier, extent);
741 i = mpz_get_ui (offset);
743 mpz_clear (multiplier);
752 /* Given a single element of an equivalence list, figure out the offset
753 from the base symbol. For simple variables or full arrays, this is
754 simply zero. For an array element we have to calculate the array
755 element number and multiply by the element size. For a substring we
756 have to calculate the further reference. */
759 calculate_offset (gfc_expr *e)
761 HOST_WIDE_INT n, element_size, offset;
762 gfc_typespec *element_type;
766 element_type = &e->symtree->n.sym->ts;
768 for (reference = e->ref; reference; reference = reference->next)
769 switch (reference->type)
772 switch (reference->u.ar.type)
778 n = element_number (&reference->u.ar);
779 if (element_type->type == BT_CHARACTER)
780 gfc_conv_const_charlen (element_type->cl);
782 int_size_in_bytes (gfc_typenode_for_spec (element_type));
783 offset += n * element_size;
787 gfc_error ("Bad array reference at %L", &e->where);
791 if (reference->u.ss.start != NULL)
792 offset += mpz_get_ui (*get_mpz (reference->u.ss.start)) - 1;
795 gfc_error ("Illegal reference type at %L as EQUIVALENCE object",
802 /* Add a new segment_info structure to the current segment. eq1 is already
803 in the list, eq2 is not. */
806 new_condition (segment_info *v, gfc_equiv *eq1, gfc_equiv *eq2)
808 HOST_WIDE_INT offset1, offset2;
811 offset1 = calculate_offset (eq1->expr);
812 offset2 = calculate_offset (eq2->expr);
814 a = get_segment_info (eq2->expr->symtree->n.sym,
815 v->offset + offset1 - offset2);
817 current_segment = add_segments (current_segment, a);
821 /* Given two equivalence structures that are both already in the list, make
822 sure that this new condition is not violated, generating an error if it
826 confirm_condition (segment_info *s1, gfc_equiv *eq1, segment_info *s2,
829 HOST_WIDE_INT offset1, offset2;
831 offset1 = calculate_offset (eq1->expr);
832 offset2 = calculate_offset (eq2->expr);
834 if (s1->offset + offset1 != s2->offset + offset2)
835 gfc_error ("Inconsistent equivalence rules involving '%s' at %L and "
836 "'%s' at %L", s1->sym->name, &s1->sym->declared_at,
837 s2->sym->name, &s2->sym->declared_at);
841 /* Process a new equivalence condition. eq1 is know to be in segment f.
842 If eq2 is also present then confirm that the condition holds.
843 Otherwise add a new variable to the segment list. */
846 add_condition (segment_info *f, gfc_equiv *eq1, gfc_equiv *eq2)
850 n = find_segment_info (eq2->expr->symtree->n.sym);
853 new_condition (f, eq1, eq2);
855 confirm_condition (f, eq1, n, eq2);
859 /* Given a segment element, search through the equivalence lists for unused
860 conditions that involve the symbol. Add these rules to the segment. */
863 find_equivalence (segment_info *n)
865 gfc_equiv *e1, *e2, *eq;
870 for (e1 = n->sym->ns->equiv; e1; e1 = e1->next)
874 /* Search the equivalence list, including the root (first) element
875 for the symbol that owns the segment. */
876 for (e2 = e1; e2; e2 = e2->eq)
878 if (!e2->used && e2->expr->symtree->n.sym == n->sym)
885 /* Go to the next root element. */
891 /* Now traverse the equivalence list matching the offsets. */
892 for (e2 = e1; e2; e2 = e2->eq)
894 if (!e2->used && e2 != eq)
896 add_condition (n, eq, e2);
906 /* Add all symbols equivalenced within a segment. We need to scan the
907 segment list multiple times to include indirect equivalences. Since
908 a new segment_info can inserted at the beginning of the segment list,
909 depending on its offset, we have to force a final pass through the
910 loop by demanding that completion sees a pass with no matches; ie.
911 all symbols with equiv_built set and no new equivalences found. */
914 add_equivalences (bool *saw_equiv)
924 for (f = current_segment; f; f = f->next)
926 if (!f->sym->equiv_built)
928 f->sym->equiv_built = 1;
929 seen_one = find_equivalence (f);
939 /* Add a copy of this segment list to the namespace. */
940 copy_equiv_list_to_ns (current_segment);
944 /* Returns the offset necessary to properly align the current equivalence.
945 Sets *palign to the required alignment. */
948 align_segment (unsigned HOST_WIDE_INT *palign)
951 unsigned HOST_WIDE_INT offset;
952 unsigned HOST_WIDE_INT max_align;
953 unsigned HOST_WIDE_INT this_align;
954 unsigned HOST_WIDE_INT this_offset;
958 for (s = current_segment; s; s = s->next)
960 this_align = TYPE_ALIGN_UNIT (s->field);
961 if (s->offset & (this_align - 1))
963 /* Field is misaligned. */
964 this_offset = this_align - ((s->offset + offset) & (this_align - 1));
965 if (this_offset & (max_align - 1))
967 /* Aligning this field would misalign a previous field. */
968 gfc_error ("The equivalence set for variable '%s' "
969 "declared at %L violates alignment requirements",
970 s->sym->name, &s->sym->declared_at);
972 offset += this_offset;
974 max_align = this_align;
982 /* Adjust segment offsets by the given amount. */
985 apply_segment_offset (segment_info *s, HOST_WIDE_INT offset)
987 for (; s; s = s->next)
992 /* Lay out a symbol in a common block. If the symbol has already been seen
993 then check the location is consistent. Otherwise create segments
994 for that symbol and all the symbols equivalenced with it. */
996 /* Translate a single common block. */
999 translate_common (gfc_common_head *common, gfc_symbol *var_list)
1003 segment_info *common_segment;
1004 HOST_WIDE_INT offset;
1005 HOST_WIDE_INT current_offset;
1006 unsigned HOST_WIDE_INT align;
1007 unsigned HOST_WIDE_INT max_align;
1010 common_segment = NULL;
1015 /* Add symbols to the segment. */
1016 for (sym = var_list; sym; sym = sym->common_next)
1018 current_segment = common_segment;
1019 s = find_segment_info (sym);
1021 /* Symbol has already been added via an equivalence. Multiple
1022 use associations of the same common block result in equiv_built
1023 being set but no information about the symbol in the segment. */
1024 if (s && sym->equiv_built)
1026 /* Ensure the current location is properly aligned. */
1027 align = TYPE_ALIGN_UNIT (s->field);
1028 current_offset = (current_offset + align - 1) &~ (align - 1);
1030 /* Verify that it ended up where we expect it. */
1031 if (s->offset != current_offset)
1033 gfc_error ("Equivalence for '%s' does not match ordering of "
1034 "COMMON '%s' at %L", sym->name,
1035 common->name, &common->where);
1040 /* A symbol we haven't seen before. */
1041 s = current_segment = get_segment_info (sym, current_offset);
1043 /* Add all objects directly or indirectly equivalenced with this
1045 add_equivalences (&saw_equiv);
1047 if (current_segment->offset < 0)
1048 gfc_error ("The equivalence set for '%s' cause an invalid "
1049 "extension to COMMON '%s' at %L", sym->name,
1050 common->name, &common->where);
1052 offset = align_segment (&align);
1054 if (offset & (max_align - 1))
1056 /* The required offset conflicts with previous alignment
1057 requirements. Insert padding immediately before this
1059 gfc_warning ("Padding of %d bytes required before '%s' in "
1060 "COMMON '%s' at %L", (int)offset, s->sym->name,
1061 common->name, &common->where);
1065 /* Offset the whole common block. */
1066 apply_segment_offset (common_segment, offset);
1069 /* Apply the offset to the new segments. */
1070 apply_segment_offset (current_segment, offset);
1071 current_offset += offset;
1072 if (max_align < align)
1075 /* Add the new segments to the common block. */
1076 common_segment = add_segments (common_segment, current_segment);
1079 /* The offset of the next common variable. */
1080 current_offset += s->length;
1083 if (common_segment == NULL)
1085 gfc_error ("COMMON '%s' at %L does not exist",
1086 common->name, &common->where);
1090 if (common_segment->offset != 0)
1092 gfc_warning ("COMMON '%s' at %L requires %d bytes of padding at start",
1093 common->name, &common->where, (int)common_segment->offset);
1096 create_common (common, common_segment, saw_equiv);
1100 /* Create a new block for each merged equivalence list. */
1103 finish_equivalences (gfc_namespace *ns)
1107 gfc_common_head * c;
1108 HOST_WIDE_INT offset;
1109 unsigned HOST_WIDE_INT align;
1112 for (z = ns->equiv; z; z = z->next)
1113 for (y = z->eq; y; y = y->eq)
1117 sym = z->expr->symtree->n.sym;
1118 current_segment = get_segment_info (sym, 0);
1120 /* All objects directly or indirectly equivalenced with this
1122 add_equivalences (&dummy);
1124 /* Align the block. */
1125 offset = align_segment (&align);
1127 /* Ensure all offsets are positive. */
1128 offset -= current_segment->offset & ~(align - 1);
1130 apply_segment_offset (current_segment, offset);
1132 /* Create the decl. If this is a module equivalence, it has a
1133 unique name, pointed to by z->module. This is written to a
1134 gfc_common_header to push create_common into using
1135 build_common_decl, so that the equivalence appears as an
1136 external symbol. Otherwise, a local declaration is built using
1137 build_equiv_decl. */
1140 c = gfc_get_common_head ();
1141 /* We've lost the real location, so use the location of the
1142 enclosing procedure. */
1143 c->where = ns->proc_name->declared_at;
1144 strcpy (c->name, z->module);
1149 create_common (c, current_segment, true);
1155 /* Work function for translating a named common block. */
1158 named_common (gfc_symtree *st)
1160 translate_common (st->n.common, st->n.common->head);
1164 /* Translate the common blocks in a namespace. Unlike other variables,
1165 these have to be created before code, because the backend_decl depends
1166 on the rest of the common block. */
1169 gfc_trans_common (gfc_namespace *ns)
1173 /* Translate the blank common block. */
1174 if (ns->blank_common.head != NULL)
1176 c = gfc_get_common_head ();
1178 /* We've lost the real location, so use the location of the
1179 enclosing procedure. */
1180 if (ns->proc_name != NULL)
1181 c->where = ns->proc_name->declared_at;
1183 c->where = ns->blank_common.head->common_head->where;
1185 strcpy (c->name, BLANK_COMMON_NAME);
1186 translate_common (c, ns->blank_common.head);
1189 /* Translate all named common blocks. */
1190 gfc_traverse_symtree (ns->common_root, named_common);
1192 /* Translate local equivalence. */
1193 finish_equivalences (ns);
1195 /* Commit the newly created symbols for common blocks and module
1197 gfc_commit_symbols ();