1 /* Routines for performing Temporary Expression Replacement (TER) in SSA trees.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation,
4 Contributed by Andrew MacLeod <amacleod@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
28 #include "diagnostic.h"
30 #include "tree-flow.h"
31 #include "tree-dump.h"
32 #include "tree-ssa-live.h"
36 /* Temporary Expression Replacement (TER)
38 Replace SSA version variables during out-of-ssa with their defining
39 expression if there is only one use of the variable.
41 This pass is required in order for the RTL expansion pass to see larger
42 chunks of code. This allows it to make better choices on RTL pattern
43 selection. When expand is rewritten and merged with out-of-ssa, and
44 understands SSA, this should be eliminated.
46 A pass is made through the function, one block at a time. No cross block
47 information is tracked.
49 Variables which only have one use, and whose defining stmt is considered
50 a replaceable expression (see is_replaceable_p) are tracked to see whether
51 they can be replaced at their use location.
57 if there are the only use of n_12 and a_2, TER will substitute in their
58 expressions in v_9, and end up with:
60 v_9 = (b_5 + 6) * (C * 10)
62 which will then have the ssa_name assigned to regular variables, and the
63 resulting code which will be passed to the expander looks something like:
65 v = (b + 6) * (C * 10)
68 This requires ensuring that none of the variables used by the expression
69 change between the def point and where it is used. Furthermore, if any
70 of the ssa_names used in this expression are themselves replaceable, we
71 have to ensure none of that expressions' arguments change either.
72 Although SSA_NAMES themselves don't change, this pass is performed after
73 coalescing has coalesced different SSA_NAMES together, so there could be a
74 definition of an SSA_NAME which is coalesced with a use that causes a
77 PHI b_5 = <b_8(2), b_14(1)>
84 If b_5, b_8 and b_14 are all coalesced together...
85 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
86 because b_8 is in fact killing the value of b_5 since they share a partition
87 and will be assigned the same memory or register location.
89 TER implements this but stepping through the instructions in a block and
90 tracking potential expressions for replacement, and the partitions they are
91 dependent on. Expressions are represented by the SSA_NAME_VERSION of the
92 DEF on the LHS of a GIMPLE_MODIFY_STMT and the expression is the RHS.
94 When a stmt is determined to be a possible replacement expression, the
95 following steps are taken:
97 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
98 def and any uses in the expression. non-NULL means the expression is being
99 tracked. The UID's themselves are used to prevent TER substitution into
100 accumulating sequences, i.e.,
106 this can result in very large expressions which don't accomplish anything
107 see PR tree-optimization/17549.
109 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
110 partition which is used in the expression. This is primarily used to remove
111 an expression from the partition kill lists when a decision is made whether
112 to replace it or not. This is indexed by ssa version number as well, and
113 indicates a partition number. virtual operands are not tracked individually,
114 but they are summarized by an artificial partition called VIRTUAL_PARTITION.
115 This means a MAY or MUST def will kill *ALL* expressions that are dependent
116 on a virtual operand.
117 Note that the EXPR_DECL_UID and this bitmap represent very similar
118 information, but the info in one is not easy to obtain from the other.
120 KILL_LIST is yet another bitmap array, this time it is indexed by partition
121 number, and represents a list of active expressions which will will no
122 longer be valid if a definition into this partition takes place.
124 PARTITION_IN_USE is simply a bitmap which is used to track which partitions
125 currently have something in their kill list. This is used at the end of
126 a block to clear out the KILL_LIST bitmaps at the end of each block.
128 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
129 dependencies which will be reused by the current definition. All the uses
130 on an expression are processed before anything else is done. If a use is
131 determined to be a replaceable expression AND the current stmt is also going
132 to be replaceable, all the dependencies of this replaceable use will be
133 picked up by the current stmt's expression. Rather than recreate them, they
134 are simply copied here and then copied into the new expression when it is
140 a_2's expression 'b_5 + 6' is determined to be replaceable at the use
141 location. It is dependent on the partition 'b_5' is in. This is cached into
142 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
143 replaceability, it is a candidate, and it is dependent on the partition
144 b_5 is in *NOT* a_2, as well as c_4's partition.
146 if v_8 is also replaceable:
150 x_9 is dependent on partitions b_5, and c_4
152 if a statement is found which has either of those partitions written to
153 before x_9 is used, then x_9 itself is NOT replaceable. */
156 /* Temporary Expression Replacement (TER) table information. */
158 typedef struct temp_expr_table_d
161 bitmap
*partition_dependencies
; /* Partitions expr is dependent on. */
162 tree
*replaceable_expressions
; /* Replacement expression table. */
163 bitmap
*expr_decl_uids
; /* Base uids of exprs. */
164 bitmap
*kill_list
; /* Expr's killed by a partition. */
165 int virtual_partition
; /* Pseudo partition for virtual ops. */
166 bitmap partition_in_use
; /* Partitions with kill entries. */
167 bitmap new_replaceable_dependencies
; /* Holding place for pending dep's. */
168 int *num_in_part
; /* # of ssa_names in a partition. */
169 } *temp_expr_table_p
;
171 /* Used to indicate a dependency on VDEFs. */
172 #define VIRTUAL_PARTITION(table) (table->virtual_partition)
174 #ifdef ENABLE_CHECKING
175 extern void debug_ter (FILE *, temp_expr_table_p
);
179 /* Create a new TER table for MAP. */
181 static temp_expr_table_p
182 new_temp_expr_table (var_map map
)
187 t
= XNEW (struct temp_expr_table_d
);
190 t
->partition_dependencies
= XCNEWVEC (bitmap
, num_ssa_names
+ 1);
191 t
->expr_decl_uids
= XCNEWVEC (bitmap
, num_ssa_names
+ 1);
192 t
->kill_list
= XCNEWVEC (bitmap
, num_var_partitions (map
) + 1);
194 t
->partition_in_use
= BITMAP_ALLOC (NULL
);
196 t
->virtual_partition
= num_var_partitions (map
);
197 t
->new_replaceable_dependencies
= BITMAP_ALLOC (NULL
);
199 t
->replaceable_expressions
= NULL
;
200 t
->num_in_part
= XCNEWVEC (int, num_var_partitions (map
));
201 for (x
= 1; x
< num_ssa_names
; x
++)
204 tree name
= ssa_name (x
);
207 p
= var_to_partition (map
, name
);
208 if (p
!= NO_PARTITION
)
216 /* Free TER table T. If there are valid replacements, return the expression
220 free_temp_expr_table (temp_expr_table_p t
)
225 #ifdef ENABLE_CHECKING
227 for (x
= 0; x
<= num_var_partitions (t
->map
); x
++)
228 gcc_assert (!t
->kill_list
[x
]);
231 BITMAP_FREE (t
->partition_in_use
);
232 BITMAP_FREE (t
->new_replaceable_dependencies
);
234 for (i
= 0; i
<= num_ssa_names
; i
++)
235 if (t
->expr_decl_uids
[i
])
236 BITMAP_FREE (t
->expr_decl_uids
[i
]);
237 free (t
->expr_decl_uids
);
240 free (t
->partition_dependencies
);
241 free (t
->num_in_part
);
243 if (t
->replaceable_expressions
)
244 ret
= t
->replaceable_expressions
;
251 /* Return TRUE if VERSION is to be replaced by an expression in TAB. */
254 version_to_be_replaced_p (temp_expr_table_p tab
, int version
)
256 if (!tab
->replaceable_expressions
)
258 return tab
->replaceable_expressions
[version
] != NULL_TREE
;
262 /* Add partition P to the list if partitions VERSION is dependent on. TAB is
263 the expression table */
266 make_dependent_on_partition (temp_expr_table_p tab
, int version
, int p
)
268 if (!tab
->partition_dependencies
[version
])
269 tab
->partition_dependencies
[version
] = BITMAP_ALLOC (NULL
);
271 bitmap_set_bit (tab
->partition_dependencies
[version
], p
);
275 /* Add VER to the kill list for P. TAB is the expression table */
278 add_to_partition_kill_list (temp_expr_table_p tab
, int p
, int ver
)
280 if (!tab
->kill_list
[p
])
282 tab
->kill_list
[p
] = BITMAP_ALLOC (NULL
);
283 bitmap_set_bit (tab
->partition_in_use
, p
);
285 bitmap_set_bit (tab
->kill_list
[p
], ver
);
289 /* Remove VER from the partition kill list for P. TAB is the expression
293 remove_from_partition_kill_list (temp_expr_table_p tab
, int p
, int version
)
295 #ifdef ENABLE_CHECKING
296 gcc_assert (tab
->kill_list
[p
]);
298 bitmap_clear_bit (tab
->kill_list
[p
], version
);
299 if (bitmap_empty_p (tab
->kill_list
[p
]))
301 bitmap_clear_bit (tab
->partition_in_use
, p
);
302 BITMAP_FREE (tab
->kill_list
[p
]);
307 /* Add a dependency between the def of ssa VERSION and VAR. If VAR is
308 replaceable by an expression, add a dependence each of the elements of the
309 expression. These are contained in the new_replaceable list. TAB is the
313 add_dependence (temp_expr_table_p tab
, int version
, tree var
)
319 i
= SSA_NAME_VERSION (var
);
320 if (version_to_be_replaced_p (tab
, i
))
322 if (!bitmap_empty_p (tab
->new_replaceable_dependencies
))
324 /* Version will now be killed by a write to any partition the
325 substituted expression would have been killed by. */
326 EXECUTE_IF_SET_IN_BITMAP (tab
->new_replaceable_dependencies
, 0, x
, bi
)
327 add_to_partition_kill_list (tab
, x
, version
);
329 /* Rather than set partition_dependencies and in_use lists bit by
330 bit, simply OR in the new_replaceable_dependencies bits. */
331 if (!tab
->partition_dependencies
[version
])
332 tab
->partition_dependencies
[version
] = BITMAP_ALLOC (NULL
);
333 bitmap_ior_into (tab
->partition_dependencies
[version
],
334 tab
->new_replaceable_dependencies
);
335 bitmap_ior_into (tab
->partition_in_use
,
336 tab
->new_replaceable_dependencies
);
337 /* It is only necessary to add these once. */
338 bitmap_clear (tab
->new_replaceable_dependencies
);
343 i
= var_to_partition (tab
->map
, var
);
344 #ifdef ENABLE_CHECKING
345 gcc_assert (i
!= NO_PARTITION
);
346 gcc_assert (tab
->num_in_part
[i
] != 0);
348 /* Only dependencies on ssa_names which are coalesced with something need
349 to be tracked. Partitions with containing only a single SSA_NAME
350 *cannot* have their value changed. */
351 if (tab
->num_in_part
[i
] > 1)
353 add_to_partition_kill_list (tab
, i
, version
);
354 make_dependent_on_partition (tab
, version
, i
);
360 /* Return TRUE if expression STMT is suitable for replacement. */
363 is_replaceable_p (tree stmt
)
368 location_t locus1
, locus2
;
371 /* Only consider modify stmts. */
372 if (TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
)
375 /* If the statement may throw an exception, it cannot be replaced. */
376 if (tree_could_throw_p (stmt
))
379 /* Punt if there is more than 1 def. */
380 def
= SINGLE_SSA_TREE_OPERAND (stmt
, SSA_OP_DEF
);
384 /* Only consider definitions which have a single use. */
385 if (!single_imm_use (def
, &use_p
, &use_stmt
))
388 /* If the use isn't in this block, it wont be replaced either. */
389 if (bb_for_stmt (use_stmt
) != bb_for_stmt (stmt
))
392 if (GIMPLE_STMT_P (stmt
))
394 locus1
= GIMPLE_STMT_LOCUS (stmt
);
395 block1
= GIMPLE_STMT_BLOCK (stmt
);
399 locus1
= *EXPR_LOCUS (stmt
);
400 block1
= TREE_BLOCK (stmt
);
402 if (GIMPLE_STMT_P (use_stmt
))
404 locus2
= GIMPLE_STMT_LOCUS (use_stmt
);
405 block2
= GIMPLE_STMT_BLOCK (use_stmt
);
407 if (TREE_CODE (use_stmt
) == PHI_NODE
)
414 locus2
= *EXPR_LOCUS (use_stmt
);
415 block2
= TREE_BLOCK (use_stmt
);
419 && ((locus1
&& locus1
!= locus2
) || (block1
&& block1
!= block2
)))
422 /* Used in this block, but at the TOP of the block, not the end. */
423 if (TREE_CODE (use_stmt
) == PHI_NODE
)
426 /* There must be no VDEFs. */
427 if (!(ZERO_SSA_OPERANDS (stmt
, SSA_OP_VDEF
)))
430 /* Without alias info we can't move around loads. */
431 if (stmt_ann (stmt
)->references_memory
&& !optimize
)
434 /* Float expressions must go through memory if float-store is on. */
436 && FLOAT_TYPE_P (TREE_TYPE (GENERIC_TREE_OPERAND (stmt
, 1))))
439 /* An assignment with a register variable on the RHS is not
441 if (TREE_CODE (GENERIC_TREE_OPERAND (stmt
, 1)) == VAR_DECL
442 && DECL_HARD_REGISTER (GENERIC_TREE_OPERAND (stmt
, 1)))
445 /* No function calls can be replaced. */
446 if ((call_expr
= get_call_expr_in (stmt
)) != NULL_TREE
)
449 /* Leave any stmt with volatile operands alone as well. */
450 if (stmt_ann (stmt
)->has_volatile_ops
)
457 /* This function will remove the expression for VERSION from replacement
458 consideration in table TAB. If FREE_EXPR is true, then remove the
459 expression from consideration as well by freeing the decl uid bitmap. */
462 finished_with_expr (temp_expr_table_p tab
, int version
, bool free_expr
)
467 /* Remove this expression from its dependent lists. The partition dependence
468 list is retained and transfered later to whomever uses this version. */
469 if (tab
->partition_dependencies
[version
])
471 EXECUTE_IF_SET_IN_BITMAP (tab
->partition_dependencies
[version
], 0, i
, bi
)
472 remove_from_partition_kill_list (tab
, i
, version
);
473 BITMAP_FREE (tab
->partition_dependencies
[version
]);
476 BITMAP_FREE (tab
->expr_decl_uids
[version
]);
480 /* Create an expression entry for a replaceable expression. */
483 process_replaceable (temp_expr_table_p tab
, tree stmt
)
485 tree var
, def
, basevar
;
488 bitmap def_vars
, use_vars
;
490 #ifdef ENABLE_CHECKING
491 gcc_assert (is_replaceable_p (stmt
));
494 def
= SINGLE_SSA_TREE_OPERAND (stmt
, SSA_OP_DEF
);
495 version
= SSA_NAME_VERSION (def
);
496 basevar
= SSA_NAME_VAR (def
);
497 def_vars
= BITMAP_ALLOC (NULL
);
499 bitmap_set_bit (def_vars
, DECL_UID (basevar
));
501 /* Add this expression to the dependency list for each use partition. */
502 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
504 int var_version
= SSA_NAME_VERSION (var
);
506 use_vars
= tab
->expr_decl_uids
[var_version
];
507 add_dependence (tab
, version
, var
);
510 bitmap_ior_into (def_vars
, use_vars
);
511 BITMAP_FREE (tab
->expr_decl_uids
[var_version
]);
514 bitmap_set_bit (def_vars
, DECL_UID (SSA_NAME_VAR (var
)));
516 tab
->expr_decl_uids
[version
] = def_vars
;
518 /* If there are VUSES, add a dependence on virtual defs. */
519 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_VUSE
))
521 make_dependent_on_partition (tab
, version
, VIRTUAL_PARTITION (tab
));
522 add_to_partition_kill_list (tab
, VIRTUAL_PARTITION (tab
), version
);
527 /* This function removes any expression in TAB which is dependent on PARTITION
528 from consideration, making it not replaceable. */
531 kill_expr (temp_expr_table_p tab
, int partition
)
535 /* Mark every active expr dependent on this var as not replaceable.
536 finished_with_expr can modify the bitmap, so we can't execute over it. */
537 while (tab
->kill_list
[partition
])
539 version
= bitmap_first_set_bit (tab
->kill_list
[partition
]);
540 finished_with_expr (tab
, version
, true);
543 #ifdef ENABLE_CHECKING
544 gcc_assert (!tab
->kill_list
[partition
]);
549 /* This function kills all expressions in TAB which are dependent on virtual
553 kill_virtual_exprs (temp_expr_table_p tab
)
555 kill_expr (tab
, VIRTUAL_PARTITION (tab
));
559 /* Mark the expression associated with VAR as replaceable, and enter
560 the defining stmt into the partition_dependencies table TAB. If
561 MORE_REPLACING is true, accumulate the pending partition dependencies. */
564 mark_replaceable (temp_expr_table_p tab
, tree var
, bool more_replacing
)
566 int version
= SSA_NAME_VERSION (var
);
568 /* Move the dependence list to the pending listpending. */
569 if (more_replacing
&& tab
->partition_dependencies
[version
])
570 bitmap_ior_into (tab
->new_replaceable_dependencies
,
571 tab
->partition_dependencies
[version
]);
573 finished_with_expr (tab
, version
, !more_replacing
);
575 /* Set the replaceable expression. */
576 if (!tab
->replaceable_expressions
)
577 tab
->replaceable_expressions
= XCNEWVEC (tree
, num_ssa_names
+ 1);
578 tab
->replaceable_expressions
[version
] = SSA_NAME_DEF_STMT (var
);
582 /* This function processes basic block BB, and looks for variables which can
583 be replaced by their expressions. Results are stored in the table TAB. */
586 find_replaceable_in_bb (temp_expr_table_p tab
, basic_block bb
)
588 block_stmt_iterator bsi
;
592 var_map map
= tab
->map
;
594 bool stmt_replaceable
;
596 for (bsi
= bsi_start (bb
); !bsi_end_p (bsi
); bsi_next (&bsi
))
598 stmt
= bsi_stmt (bsi
);
599 ann
= stmt_ann (stmt
);
601 stmt_replaceable
= is_replaceable_p (stmt
);
602 /* Determine if this stmt finishes an existing expression. */
603 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
605 unsigned ver
= SSA_NAME_VERSION (use
);
607 /* If this use is a potential replacement variable, process it. */
608 if (tab
->expr_decl_uids
[ver
])
610 bool same_root_var
= false;
612 bitmap vars
= tab
->expr_decl_uids
[ver
];
614 /* See if the root variables are the same. If they are, we
615 do not want to do the replacement to avoid problems with
616 code size, see PR tree-optimization/17549. */
617 if (!bitmap_empty_p (vars
))
618 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter2
, SSA_OP_DEF
)
620 if (bitmap_bit_p (vars
, DECL_UID (SSA_NAME_VAR (def
))))
622 same_root_var
= true;
627 /* Mark expression as replaceable unless stmt is volatile or the
628 def variable has the same root variable as something in the
629 substitution list. */
630 if (ann
->has_volatile_ops
|| same_root_var
)
631 finished_with_expr (tab
, ver
, true);
633 mark_replaceable (tab
, use
, stmt_replaceable
);
637 /* Next, see if this stmt kills off an active expression. */
638 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_DEF
)
640 partition
= var_to_partition (map
, def
);
641 if (partition
!= NO_PARTITION
&& tab
->kill_list
[partition
])
642 kill_expr (tab
, partition
);
645 /* Now see if we are creating a new expression or not. */
646 if (stmt_replaceable
)
647 process_replaceable (tab
, stmt
);
649 /* Free any unused dependency lists. */
650 bitmap_clear (tab
->new_replaceable_dependencies
);
652 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
653 including the current stmt. */
654 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_VIRTUAL_DEFS
))
655 kill_virtual_exprs (tab
);
660 /* This function is the driver routine for replacement of temporary expressions
661 in the SSA->normal phase, operating on MAP. If there are replaceable
662 expressions, a table is returned which maps SSA versions to the
663 expressions they should be replaced with. A NULL_TREE indicates no
664 replacement should take place. If there are no replacements at all,
665 NULL is returned by the function, otherwise an expression vector indexed
666 by SSA_NAME version numbers. */
669 find_replaceable_exprs (var_map map
)
672 temp_expr_table_p table
;
675 table
= new_temp_expr_table (map
);
678 find_replaceable_in_bb (table
, bb
);
679 gcc_assert (bitmap_empty_p (table
->partition_in_use
));
681 #ifdef ENABLE_CHECKING
684 /* Make sure all the tables have been cleared out. */
685 for (i
= 0; i
< num_ssa_names
+ 1; i
++)
687 gcc_assert (table
->partition_dependencies
[i
] == NULL
);
688 gcc_assert (table
->expr_decl_uids
[i
] == NULL
);
689 if (i
< num_var_partitions (map
))
690 gcc_assert (table
->kill_list
[i
] == NULL
);
696 ret
= free_temp_expr_table (table
);
701 /* Dump TER expression table EXPR to file F. */
704 dump_replaceable_exprs (FILE *f
, tree
*expr
)
709 fprintf (f
, "\nReplacing Expressions\n");
710 for (x
= 0; x
< (int)num_ssa_names
; x
++)
714 var
= SINGLE_SSA_TREE_OPERAND (stmt
, SSA_OP_DEF
);
715 gcc_assert (var
!= NULL_TREE
);
716 print_generic_expr (f
, var
, TDF_SLIM
);
717 fprintf (f
, " replace with --> ");
718 print_generic_expr (f
, GENERIC_TREE_OPERAND (stmt
, 1),
726 #ifdef ENABLE_CHECKING
727 /* Dump the status of the various tables in the expression table. This is used
728 exclusively to debug TER. F is the place to send debug info and T is the
729 table being debugged. */
732 debug_ter (FILE *f
, temp_expr_table_p t
)
737 fprintf (f
, "\nDumping current state of TER\n virtual partition = %d\n",
738 VIRTUAL_PARTITION (t
));
739 if (t
->replaceable_expressions
)
740 dump_replaceable_exprs (f
, t
->replaceable_expressions
);
741 fprintf (f
, "Currently tracking the following expressions:\n");
743 for (x
= 1; x
< num_ssa_names
; x
++)
744 if (t
->expr_decl_uids
[x
])
746 print_generic_expr (stderr
, ssa_name (x
), TDF_SLIM
);
747 fprintf (f
, " dep-parts : ");
748 if (t
->partition_dependencies
[x
]
749 && !bitmap_empty_p (t
->partition_dependencies
[x
]))
751 EXECUTE_IF_SET_IN_BITMAP (t
->partition_dependencies
[x
], 0, y
, bi
)
752 fprintf (f
, "P%d ",y
);
754 fprintf (stderr
, " basedecls: ");
755 EXECUTE_IF_SET_IN_BITMAP (t
->expr_decl_uids
[x
], 0, y
, bi
)
756 fprintf (f
, "%d ",y
);
757 fprintf (stderr
, "\n");
760 bitmap_print (f
, t
->partition_in_use
, "Partitions in use ",
761 "\npartition KILL lists:\n");
763 for (x
= 0; x
<= num_var_partitions (t
->map
); x
++)
766 fprintf (f
, "Partition %d : ", x
);
767 EXECUTE_IF_SET_IN_BITMAP (t
->kill_list
[x
], 0, y
, bi
)
768 fprintf (f
, "_%d ",y
);
771 fprintf (f
, "\n----------\n");