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 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
.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 (FIELD_DECL
, name
, h
->field
);
282 gfc_set_decl_location (field
, &h
->sym
->declared_at
);
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
);
325 /* Get storage for local equivalence. */
328 build_equiv_decl (tree union_type
, bool is_init
, bool is_saved
)
332 static int serial
= 0;
336 decl
= gfc_create_var (union_type
, "equiv");
337 TREE_STATIC (decl
) = 1;
338 GFC_DECL_COMMON_OR_EQUIV (decl
) = 1;
342 snprintf (name
, sizeof (name
), "equiv.%d", serial
++);
343 decl
= build_decl (VAR_DECL
, get_identifier (name
), union_type
);
344 DECL_ARTIFICIAL (decl
) = 1;
345 DECL_IGNORED_P (decl
) = 1;
347 if (!gfc_can_put_var_on_stack (DECL_SIZE_UNIT (decl
))
349 TREE_STATIC (decl
) = 1;
351 TREE_ADDRESSABLE (decl
) = 1;
352 TREE_USED (decl
) = 1;
353 GFC_DECL_COMMON_OR_EQUIV (decl
) = 1;
355 /* The source location has been lost, and doesn't really matter.
356 We need to set it to something though. */
357 gfc_set_decl_location (decl
, &gfc_current_locus
);
359 gfc_add_decl_to_function (decl
);
365 /* Get storage for common block. */
368 build_common_decl (gfc_common_head
*com
, tree union_type
, bool is_init
)
370 gfc_symbol
*common_sym
;
373 /* Create a namespace to store symbols for common blocks. */
374 if (gfc_common_ns
== NULL
)
375 gfc_common_ns
= gfc_get_namespace (NULL
, 0);
377 gfc_get_symbol (com
->name
, gfc_common_ns
, &common_sym
);
378 decl
= common_sym
->backend_decl
;
380 /* Update the size of this common block as needed. */
381 if (decl
!= NULL_TREE
)
383 tree size
= TYPE_SIZE_UNIT (union_type
);
384 if (tree_int_cst_lt (DECL_SIZE_UNIT (decl
), size
))
386 /* Named common blocks of the same name shall be of the same size
387 in all scoping units of a program in which they appear, but
388 blank common blocks may be of different sizes. */
389 if (strcmp (com
->name
, BLANK_COMMON_NAME
))
390 gfc_warning ("Named COMMON block '%s' at %L shall be of the "
391 "same size", com
->name
, &com
->where
);
392 DECL_SIZE_UNIT (decl
) = size
;
393 TREE_TYPE (decl
) = union_type
;
397 /* If this common block has been declared in a previous program unit,
398 and either it is already initialized or there is no new initialization
399 for it, just return. */
400 if ((decl
!= NULL_TREE
) && (!is_init
|| DECL_INITIAL (decl
)))
403 /* If there is no backend_decl for the common block, build it. */
404 if (decl
== NULL_TREE
)
406 decl
= build_decl (VAR_DECL
, get_identifier (com
->name
), union_type
);
407 SET_DECL_ASSEMBLER_NAME (decl
, gfc_sym_mangled_common_id (com
));
408 TREE_PUBLIC (decl
) = 1;
409 TREE_STATIC (decl
) = 1;
410 DECL_ALIGN (decl
) = BIGGEST_ALIGNMENT
;
411 DECL_USER_ALIGN (decl
) = 0;
412 GFC_DECL_COMMON_OR_EQUIV (decl
) = 1;
414 gfc_set_decl_location (decl
, &com
->where
);
416 if (com
->threadprivate
)
417 DECL_TLS_MODEL (decl
) = decl_default_tls_model (decl
);
419 /* Place the back end declaration for this common block in
420 GLOBAL_BINDING_LEVEL. */
421 common_sym
->backend_decl
= pushdecl_top_level (decl
);
424 /* Has no initial values. */
427 DECL_INITIAL (decl
) = NULL_TREE
;
428 DECL_COMMON (decl
) = 1;
429 DECL_DEFER_OUTPUT (decl
) = 1;
433 DECL_INITIAL (decl
) = error_mark_node
;
434 DECL_COMMON (decl
) = 0;
435 DECL_DEFER_OUTPUT (decl
) = 0;
441 /* Return a field that is the size of the union, if an equivalence has
442 overlapping initializers. Merge the initializers into a single
443 initializer for this new field, then free the old ones. */
446 get_init_field (segment_info
*head
, tree union_type
, tree
*field_init
,
447 record_layout_info rli
)
450 HOST_WIDE_INT length
= 0;
451 HOST_WIDE_INT offset
= 0;
452 unsigned HOST_WIDE_INT known_align
, desired_align
;
453 bool overlap
= false;
456 unsigned char *data
, *chk
;
457 VEC(constructor_elt
,gc
) *v
= NULL
;
459 tree type
= unsigned_char_type_node
;
462 /* Obtain the size of the union and check if there are any overlapping
464 for (s
= head
; s
; s
= s
->next
)
466 HOST_WIDE_INT slen
= s
->offset
+ s
->length
;
469 if (s
->offset
< offset
)
473 length
= length
< slen
? slen
: length
;
479 /* Now absorb all the initializer data into a single vector,
480 whilst checking for overlapping, unequal values. */
481 data
= (unsigned char*)gfc_getmem ((size_t)length
);
482 chk
= (unsigned char*)gfc_getmem ((size_t)length
);
484 /* TODO - change this when default initialization is implemented. */
485 memset (data
, '\0', (size_t)length
);
486 memset (chk
, '\0', (size_t)length
);
487 for (s
= head
; s
; s
= s
->next
)
489 gfc_merge_initializers (s
->sym
->ts
, s
->sym
->value
,
494 for (i
= 0; i
< length
; i
++)
495 CONSTRUCTOR_APPEND_ELT (v
, NULL
, build_int_cst (type
, data
[i
]));
500 /* Build a char[length] array to hold the initializers. Much of what
501 follows is borrowed from build_field, above. */
503 tmp
= build_int_cst (gfc_array_index_type
, length
- 1);
504 tmp
= build_range_type (gfc_array_index_type
,
505 gfc_index_zero_node
, tmp
);
506 tmp
= build_array_type (type
, tmp
);
507 field
= build_decl (FIELD_DECL
, NULL_TREE
, tmp
);
508 gfc_set_decl_location (field
, &gfc_current_locus
);
510 known_align
= BIGGEST_ALIGNMENT
;
512 desired_align
= update_alignment_for_field (rli
, field
, known_align
);
513 if (desired_align
> known_align
)
514 DECL_PACKED (field
) = 1;
516 DECL_FIELD_CONTEXT (field
) = union_type
;
517 DECL_FIELD_OFFSET (field
) = size_int (0);
518 DECL_FIELD_BIT_OFFSET (field
) = bitsize_zero_node
;
519 SET_DECL_OFFSET_ALIGN (field
, known_align
);
521 rli
->offset
= size_binop (MAX_EXPR
, rli
->offset
,
522 size_binop (PLUS_EXPR
,
523 DECL_FIELD_OFFSET (field
),
524 DECL_SIZE_UNIT (field
)));
526 init
= build_constructor (TREE_TYPE (field
), v
);
527 TREE_CONSTANT (init
) = 1;
528 TREE_INVARIANT (init
) = 1;
532 for (s
= head
; s
; s
= s
->next
)
534 if (s
->sym
->value
== NULL
)
537 gfc_free_expr (s
->sym
->value
);
538 s
->sym
->value
= NULL
;
545 /* Declare memory for the common block or local equivalence, and create
546 backend declarations for all of the elements. */
549 create_common (gfc_common_head
*com
, segment_info
*head
, bool saw_equiv
)
551 segment_info
*s
, *next_s
;
555 tree field_init
= NULL_TREE
;
556 record_layout_info rli
;
558 bool is_init
= false;
559 bool is_saved
= false;
561 /* Declare the variables inside the common block.
562 If the current common block contains any equivalence object, then
563 make a UNION_TYPE node, otherwise RECORD_TYPE. This will let the
564 alias analyzer work well when there is no address overlapping for
565 common variables in the current common block. */
567 union_type
= make_node (UNION_TYPE
);
569 union_type
= make_node (RECORD_TYPE
);
571 rli
= start_record_layout (union_type
);
572 field_link
= &TYPE_FIELDS (union_type
);
574 /* Check for overlapping initializers and replace them with a single,
575 artificial field that contains all the data. */
577 field
= get_init_field (head
, union_type
, &field_init
, rli
);
581 if (field
!= NULL_TREE
)
585 field_link
= &TREE_CHAIN (field
);
588 for (s
= head
; s
; s
= s
->next
)
590 build_field (s
, union_type
, rli
);
592 /* Link the field into the type. */
593 *field_link
= s
->field
;
594 field_link
= &TREE_CHAIN (s
->field
);
596 /* Has initial value. */
600 /* Has SAVE attribute. */
601 if (s
->sym
->attr
.save
)
605 finish_record_layout (rli
, true);
608 decl
= build_common_decl (com
, union_type
, is_init
);
610 decl
= build_equiv_decl (union_type
, is_init
, is_saved
);
615 HOST_WIDE_INT offset
= 0;
616 VEC(constructor_elt
,gc
) *v
= NULL
;
618 if (field
!= NULL_TREE
&& field_init
!= NULL_TREE
)
619 CONSTRUCTOR_APPEND_ELT (v
, field
, field_init
);
621 for (s
= head
; s
; s
= s
->next
)
625 /* Add the initializer for this field. */
626 tmp
= gfc_conv_initializer (s
->sym
->value
, &s
->sym
->ts
,
627 TREE_TYPE (s
->field
), s
->sym
->attr
.dimension
,
628 s
->sym
->attr
.pointer
|| s
->sym
->attr
.allocatable
);
630 CONSTRUCTOR_APPEND_ELT (v
, s
->field
, tmp
);
631 offset
= s
->offset
+ s
->length
;
635 gcc_assert (!VEC_empty (constructor_elt
, v
));
636 ctor
= build_constructor (union_type
, v
);
637 TREE_CONSTANT (ctor
) = 1;
638 TREE_INVARIANT (ctor
) = 1;
639 TREE_STATIC (ctor
) = 1;
640 DECL_INITIAL (decl
) = ctor
;
642 #ifdef ENABLE_CHECKING
645 unsigned HOST_WIDE_INT idx
;
646 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), idx
, field
, value
)
647 gcc_assert (TREE_CODE (field
) == FIELD_DECL
);
652 /* Build component reference for each variable. */
653 for (s
= head
; s
; s
= next_s
)
657 var_decl
= build_decl (VAR_DECL
, DECL_NAME (s
->field
),
658 TREE_TYPE (s
->field
));
659 gfc_set_decl_location (var_decl
, &s
->sym
->declared_at
);
660 TREE_PUBLIC (var_decl
) = TREE_PUBLIC (decl
);
661 TREE_STATIC (var_decl
) = TREE_STATIC (decl
);
662 TREE_USED (var_decl
) = TREE_USED (decl
);
663 if (s
->sym
->attr
.target
)
664 TREE_ADDRESSABLE (var_decl
) = 1;
665 /* This is a fake variable just for debugging purposes. */
666 TREE_ASM_WRITTEN (var_decl
) = 1;
669 var_decl
= pushdecl_top_level (var_decl
);
671 gfc_add_decl_to_function (var_decl
);
673 SET_DECL_VALUE_EXPR (var_decl
,
674 build3 (COMPONENT_REF
, TREE_TYPE (s
->field
),
675 decl
, s
->field
, NULL_TREE
));
676 DECL_HAS_VALUE_EXPR_P (var_decl
) = 1;
677 GFC_DECL_COMMON_OR_EQUIV (var_decl
) = 1;
679 if (s
->sym
->attr
.assign
)
681 gfc_allocate_lang_decl (var_decl
);
682 GFC_DECL_ASSIGN (var_decl
) = 1;
683 GFC_DECL_STRING_LEN (var_decl
) = GFC_DECL_STRING_LEN (s
->field
);
684 GFC_DECL_ASSIGN_ADDR (var_decl
) = GFC_DECL_ASSIGN_ADDR (s
->field
);
687 s
->sym
->backend_decl
= var_decl
;
695 /* Given a symbol, find it in the current segment list. Returns NULL if
698 static segment_info
*
699 find_segment_info (gfc_symbol
*symbol
)
703 for (n
= current_segment
; n
; n
= n
->next
)
705 if (n
->sym
== symbol
)
713 /* Given an expression node, make sure it is a constant integer and return
717 get_mpz (gfc_expr
*e
)
720 if (e
->expr_type
!= EXPR_CONSTANT
)
721 gfc_internal_error ("get_mpz(): Not an integer constant");
723 return &e
->value
.integer
;
727 /* Given an array specification and an array reference, figure out the
728 array element number (zero based). Bounds and elements are guaranteed
729 to be constants. If something goes wrong we generate an error and
733 element_number (gfc_array_ref
*ar
)
735 mpz_t multiplier
, offset
, extent
, n
;
737 HOST_WIDE_INT i
, rank
;
741 mpz_init_set_ui (multiplier
, 1);
742 mpz_init_set_ui (offset
, 0);
746 for (i
= 0; i
< rank
; i
++)
748 if (ar
->dimen_type
[i
] != DIMEN_ELEMENT
)
749 gfc_internal_error ("element_number(): Bad dimension type");
751 mpz_sub (n
, *get_mpz (ar
->start
[i
]), *get_mpz (as
->lower
[i
]));
753 mpz_mul (n
, n
, multiplier
);
754 mpz_add (offset
, offset
, n
);
756 mpz_sub (extent
, *get_mpz (as
->upper
[i
]), *get_mpz (as
->lower
[i
]));
757 mpz_add_ui (extent
, extent
, 1);
759 if (mpz_sgn (extent
) < 0)
760 mpz_set_ui (extent
, 0);
762 mpz_mul (multiplier
, multiplier
, extent
);
765 i
= mpz_get_ui (offset
);
767 mpz_clear (multiplier
);
776 /* Given a single element of an equivalence list, figure out the offset
777 from the base symbol. For simple variables or full arrays, this is
778 simply zero. For an array element we have to calculate the array
779 element number and multiply by the element size. For a substring we
780 have to calculate the further reference. */
783 calculate_offset (gfc_expr
*e
)
785 HOST_WIDE_INT n
, element_size
, offset
;
786 gfc_typespec
*element_type
;
790 element_type
= &e
->symtree
->n
.sym
->ts
;
792 for (reference
= e
->ref
; reference
; reference
= reference
->next
)
793 switch (reference
->type
)
796 switch (reference
->u
.ar
.type
)
802 n
= element_number (&reference
->u
.ar
);
803 if (element_type
->type
== BT_CHARACTER
)
804 gfc_conv_const_charlen (element_type
->cl
);
806 int_size_in_bytes (gfc_typenode_for_spec (element_type
));
807 offset
+= n
* element_size
;
811 gfc_error ("Bad array reference at %L", &e
->where
);
815 if (reference
->u
.ss
.start
!= NULL
)
816 offset
+= mpz_get_ui (*get_mpz (reference
->u
.ss
.start
)) - 1;
819 gfc_error ("Illegal reference type at %L as EQUIVALENCE object",
826 /* Add a new segment_info structure to the current segment. eq1 is already
827 in the list, eq2 is not. */
830 new_condition (segment_info
*v
, gfc_equiv
*eq1
, gfc_equiv
*eq2
)
832 HOST_WIDE_INT offset1
, offset2
;
835 offset1
= calculate_offset (eq1
->expr
);
836 offset2
= calculate_offset (eq2
->expr
);
838 a
= get_segment_info (eq2
->expr
->symtree
->n
.sym
,
839 v
->offset
+ offset1
- offset2
);
841 current_segment
= add_segments (current_segment
, a
);
845 /* Given two equivalence structures that are both already in the list, make
846 sure that this new condition is not violated, generating an error if it
850 confirm_condition (segment_info
*s1
, gfc_equiv
*eq1
, segment_info
*s2
,
853 HOST_WIDE_INT offset1
, offset2
;
855 offset1
= calculate_offset (eq1
->expr
);
856 offset2
= calculate_offset (eq2
->expr
);
858 if (s1
->offset
+ offset1
!= s2
->offset
+ offset2
)
859 gfc_error ("Inconsistent equivalence rules involving '%s' at %L and "
860 "'%s' at %L", s1
->sym
->name
, &s1
->sym
->declared_at
,
861 s2
->sym
->name
, &s2
->sym
->declared_at
);
865 /* Process a new equivalence condition. eq1 is know to be in segment f.
866 If eq2 is also present then confirm that the condition holds.
867 Otherwise add a new variable to the segment list. */
870 add_condition (segment_info
*f
, gfc_equiv
*eq1
, gfc_equiv
*eq2
)
874 n
= find_segment_info (eq2
->expr
->symtree
->n
.sym
);
877 new_condition (f
, eq1
, eq2
);
879 confirm_condition (f
, eq1
, n
, eq2
);
883 /* Given a segment element, search through the equivalence lists for unused
884 conditions that involve the symbol. Add these rules to the segment. */
887 find_equivalence (segment_info
*n
)
889 gfc_equiv
*e1
, *e2
, *eq
;
894 for (e1
= n
->sym
->ns
->equiv
; e1
; e1
= e1
->next
)
898 /* Search the equivalence list, including the root (first) element
899 for the symbol that owns the segment. */
900 for (e2
= e1
; e2
; e2
= e2
->eq
)
902 if (!e2
->used
&& e2
->expr
->symtree
->n
.sym
== n
->sym
)
909 /* Go to the next root element. */
915 /* Now traverse the equivalence list matching the offsets. */
916 for (e2
= e1
; e2
; e2
= e2
->eq
)
918 if (!e2
->used
&& e2
!= eq
)
920 add_condition (n
, eq
, e2
);
930 /* Add all symbols equivalenced within a segment. We need to scan the
931 segment list multiple times to include indirect equivalences. Since
932 a new segment_info can inserted at the beginning of the segment list,
933 depending on its offset, we have to force a final pass through the
934 loop by demanding that completion sees a pass with no matches; ie.
935 all symbols with equiv_built set and no new equivalences found. */
938 add_equivalences (bool *saw_equiv
)
948 for (f
= current_segment
; f
; f
= f
->next
)
950 if (!f
->sym
->equiv_built
)
952 f
->sym
->equiv_built
= 1;
953 seen_one
= find_equivalence (f
);
963 /* Add a copy of this segment list to the namespace. */
964 copy_equiv_list_to_ns (current_segment
);
968 /* Returns the offset necessary to properly align the current equivalence.
969 Sets *palign to the required alignment. */
972 align_segment (unsigned HOST_WIDE_INT
*palign
)
975 unsigned HOST_WIDE_INT offset
;
976 unsigned HOST_WIDE_INT max_align
;
977 unsigned HOST_WIDE_INT this_align
;
978 unsigned HOST_WIDE_INT this_offset
;
982 for (s
= current_segment
; s
; s
= s
->next
)
984 this_align
= TYPE_ALIGN_UNIT (s
->field
);
985 if (s
->offset
& (this_align
- 1))
987 /* Field is misaligned. */
988 this_offset
= this_align
- ((s
->offset
+ offset
) & (this_align
- 1));
989 if (this_offset
& (max_align
- 1))
991 /* Aligning this field would misalign a previous field. */
992 gfc_error ("The equivalence set for variable '%s' "
993 "declared at %L violates alignment requirements",
994 s
->sym
->name
, &s
->sym
->declared_at
);
996 offset
+= this_offset
;
998 max_align
= this_align
;
1001 *palign
= max_align
;
1006 /* Adjust segment offsets by the given amount. */
1009 apply_segment_offset (segment_info
*s
, HOST_WIDE_INT offset
)
1011 for (; s
; s
= s
->next
)
1012 s
->offset
+= offset
;
1016 /* Lay out a symbol in a common block. If the symbol has already been seen
1017 then check the location is consistent. Otherwise create segments
1018 for that symbol and all the symbols equivalenced with it. */
1020 /* Translate a single common block. */
1023 translate_common (gfc_common_head
*common
, gfc_symbol
*var_list
)
1027 segment_info
*common_segment
;
1028 HOST_WIDE_INT offset
;
1029 HOST_WIDE_INT current_offset
;
1030 unsigned HOST_WIDE_INT align
;
1031 unsigned HOST_WIDE_INT max_align
;
1034 common_segment
= NULL
;
1039 /* Add symbols to the segment. */
1040 for (sym
= var_list
; sym
; sym
= sym
->common_next
)
1042 current_segment
= common_segment
;
1043 s
= find_segment_info (sym
);
1045 /* Symbol has already been added via an equivalence. Multiple
1046 use associations of the same common block result in equiv_built
1047 being set but no information about the symbol in the segment. */
1048 if (s
&& sym
->equiv_built
)
1050 /* Ensure the current location is properly aligned. */
1051 align
= TYPE_ALIGN_UNIT (s
->field
);
1052 current_offset
= (current_offset
+ align
- 1) &~ (align
- 1);
1054 /* Verify that it ended up where we expect it. */
1055 if (s
->offset
!= current_offset
)
1057 gfc_error ("Equivalence for '%s' does not match ordering of "
1058 "COMMON '%s' at %L", sym
->name
,
1059 common
->name
, &common
->where
);
1064 /* A symbol we haven't seen before. */
1065 s
= current_segment
= get_segment_info (sym
, current_offset
);
1067 /* Add all objects directly or indirectly equivalenced with this
1069 add_equivalences (&saw_equiv
);
1071 if (current_segment
->offset
< 0)
1072 gfc_error ("The equivalence set for '%s' cause an invalid "
1073 "extension to COMMON '%s' at %L", sym
->name
,
1074 common
->name
, &common
->where
);
1076 offset
= align_segment (&align
);
1078 if (offset
& (max_align
- 1))
1080 /* The required offset conflicts with previous alignment
1081 requirements. Insert padding immediately before this
1083 gfc_warning ("Padding of %d bytes required before '%s' in "
1084 "COMMON '%s' at %L", (int)offset
, s
->sym
->name
,
1085 common
->name
, &common
->where
);
1089 /* Offset the whole common block. */
1090 apply_segment_offset (common_segment
, offset
);
1093 /* Apply the offset to the new segments. */
1094 apply_segment_offset (current_segment
, offset
);
1095 current_offset
+= offset
;
1096 if (max_align
< align
)
1099 /* Add the new segments to the common block. */
1100 common_segment
= add_segments (common_segment
, current_segment
);
1103 /* The offset of the next common variable. */
1104 current_offset
+= s
->length
;
1107 if (common_segment
== NULL
)
1109 gfc_error ("COMMON '%s' at %L does not exist",
1110 common
->name
, &common
->where
);
1114 if (common_segment
->offset
!= 0)
1116 gfc_warning ("COMMON '%s' at %L requires %d bytes of padding at start",
1117 common
->name
, &common
->where
, (int)common_segment
->offset
);
1120 create_common (common
, common_segment
, saw_equiv
);
1124 /* Create a new block for each merged equivalence list. */
1127 finish_equivalences (gfc_namespace
*ns
)
1131 gfc_common_head
* c
;
1132 HOST_WIDE_INT offset
;
1133 unsigned HOST_WIDE_INT align
;
1136 for (z
= ns
->equiv
; z
; z
= z
->next
)
1137 for (y
= z
->eq
; y
; y
= y
->eq
)
1141 sym
= z
->expr
->symtree
->n
.sym
;
1142 current_segment
= get_segment_info (sym
, 0);
1144 /* All objects directly or indirectly equivalenced with this
1146 add_equivalences (&dummy
);
1148 /* Align the block. */
1149 offset
= align_segment (&align
);
1151 /* Ensure all offsets are positive. */
1152 offset
-= current_segment
->offset
& ~(align
- 1);
1154 apply_segment_offset (current_segment
, offset
);
1156 /* Create the decl. If this is a module equivalence, it has a
1157 unique name, pointed to by z->module. This is written to a
1158 gfc_common_header to push create_common into using
1159 build_common_decl, so that the equivalence appears as an
1160 external symbol. Otherwise, a local declaration is built using
1161 build_equiv_decl. */
1164 c
= gfc_get_common_head ();
1165 /* We've lost the real location, so use the location of the
1166 enclosing procedure. */
1167 c
->where
= ns
->proc_name
->declared_at
;
1168 strcpy (c
->name
, z
->module
);
1173 create_common (c
, current_segment
, true);
1179 /* Work function for translating a named common block. */
1182 named_common (gfc_symtree
*st
)
1184 translate_common (st
->n
.common
, st
->n
.common
->head
);
1188 /* Translate the common blocks in a namespace. Unlike other variables,
1189 these have to be created before code, because the backend_decl depends
1190 on the rest of the common block. */
1193 gfc_trans_common (gfc_namespace
*ns
)
1197 /* Translate the blank common block. */
1198 if (ns
->blank_common
.head
!= NULL
)
1200 c
= gfc_get_common_head ();
1202 /* We've lost the real location, so use the location of the
1203 enclosing procedure. */
1204 if (ns
->proc_name
!= NULL
)
1205 c
->where
= ns
->proc_name
->declared_at
;
1207 c
->where
= ns
->blank_common
.head
->common_head
->where
;
1209 strcpy (c
->name
, BLANK_COMMON_NAME
);
1210 translate_common (c
, ns
->blank_common
.head
);
1213 /* Translate all named common blocks. */
1214 gfc_traverse_symtree (ns
->common_root
, named_common
);
1216 /* Translate local equivalence. */
1217 finish_equivalences (ns
);
1219 /* Commit the newly created symbols for common blocks and module
1221 gfc_commit_symbols ();