1 /* __builtin_object_size (ptr, object_size_type) computation
2 Copyright (C) 2004-2013 Free Software Foundation, Inc.
3 Contributed by Jakub Jelinek <jakub@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
26 #include "diagnostic-core.h"
27 #include "gimple-pretty-print.h"
28 #include "tree-flow.h"
29 #include "tree-pass.h"
30 #include "tree-ssa-propagate.h"
32 struct object_size_info
35 bitmap visited
, reexamine
;
39 unsigned int *stack
, *tos
;
42 static unsigned HOST_WIDE_INT unknown
[4] = { -1, -1, 0, 0 };
44 static tree
compute_object_offset (const_tree
, const_tree
);
45 static unsigned HOST_WIDE_INT
addr_object_size (struct object_size_info
*,
47 static unsigned HOST_WIDE_INT
alloc_object_size (const_gimple
, int);
48 static tree
pass_through_call (const_gimple
);
49 static void collect_object_sizes_for (struct object_size_info
*, tree
);
50 static void expr_object_size (struct object_size_info
*, tree
, tree
);
51 static bool merge_object_sizes (struct object_size_info
*, tree
, tree
,
52 unsigned HOST_WIDE_INT
);
53 static bool plus_stmt_object_size (struct object_size_info
*, tree
, gimple
);
54 static bool cond_expr_object_size (struct object_size_info
*, tree
, gimple
);
55 static unsigned int compute_object_sizes (void);
56 static void init_offset_limit (void);
57 static void check_for_plus_in_loops (struct object_size_info
*, tree
);
58 static void check_for_plus_in_loops_1 (struct object_size_info
*, tree
,
61 /* object_sizes[0] is upper bound for number of bytes till the end of
63 object_sizes[1] is upper bound for number of bytes till the end of
64 the subobject (innermost array or field with address taken).
65 object_sizes[2] is lower bound for number of bytes till the end of
66 the object and object_sizes[3] lower bound for subobject. */
67 static unsigned HOST_WIDE_INT
*object_sizes
[4];
69 /* Bitmaps what object sizes have been computed already. */
70 static bitmap computed
[4];
72 /* Maximum value of offset we consider to be addition. */
73 static unsigned HOST_WIDE_INT offset_limit
;
76 /* Initialize OFFSET_LIMIT variable. */
78 init_offset_limit (void)
80 if (host_integerp (TYPE_MAX_VALUE (sizetype
), 1))
81 offset_limit
= tree_low_cst (TYPE_MAX_VALUE (sizetype
), 1);
88 /* Compute offset of EXPR within VAR. Return error_mark_node
92 compute_object_offset (const_tree expr
, const_tree var
)
94 enum tree_code code
= PLUS_EXPR
;
98 return size_zero_node
;
100 switch (TREE_CODE (expr
))
103 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
104 if (base
== error_mark_node
)
107 t
= TREE_OPERAND (expr
, 1);
108 off
= size_binop (PLUS_EXPR
, DECL_FIELD_OFFSET (t
),
109 size_int (tree_low_cst (DECL_FIELD_BIT_OFFSET (t
), 1)
115 case VIEW_CONVERT_EXPR
:
116 case NON_LVALUE_EXPR
:
117 return compute_object_offset (TREE_OPERAND (expr
, 0), var
);
120 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
121 if (base
== error_mark_node
)
124 off
= TYPE_SIZE_UNIT (TREE_TYPE (expr
));
128 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
129 if (base
== error_mark_node
)
132 t
= TREE_OPERAND (expr
, 1);
133 if (TREE_CODE (t
) == INTEGER_CST
&& tree_int_cst_sgn (t
) < 0)
136 t
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (t
), t
);
138 t
= fold_convert (sizetype
, t
);
139 off
= size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (TREE_TYPE (expr
)), t
);
143 gcc_assert (TREE_CODE (TREE_OPERAND (expr
, 0)) == ADDR_EXPR
);
144 return double_int_to_tree (sizetype
, mem_ref_offset (expr
));
147 return error_mark_node
;
150 return size_binop (code
, base
, off
);
154 /* Compute __builtin_object_size for PTR, which is a ADDR_EXPR.
155 OBJECT_SIZE_TYPE is the second argument from __builtin_object_size.
156 If unknown, return unknown[object_size_type]. */
158 static unsigned HOST_WIDE_INT
159 addr_object_size (struct object_size_info
*osi
, const_tree ptr
,
160 int object_size_type
)
162 tree pt_var
, pt_var_size
= NULL_TREE
, var_size
, bytes
;
164 gcc_assert (TREE_CODE (ptr
) == ADDR_EXPR
);
166 pt_var
= TREE_OPERAND (ptr
, 0);
167 while (handled_component_p (pt_var
))
168 pt_var
= TREE_OPERAND (pt_var
, 0);
171 && TREE_CODE (pt_var
) == MEM_REF
)
173 unsigned HOST_WIDE_INT sz
;
175 if (!osi
|| (object_size_type
& 1) != 0
176 || TREE_CODE (TREE_OPERAND (pt_var
, 0)) != SSA_NAME
)
178 sz
= compute_builtin_object_size (TREE_OPERAND (pt_var
, 0),
179 object_size_type
& ~1);
183 tree var
= TREE_OPERAND (pt_var
, 0);
185 collect_object_sizes_for (osi
, var
);
186 if (bitmap_bit_p (computed
[object_size_type
],
187 SSA_NAME_VERSION (var
)))
188 sz
= object_sizes
[object_size_type
][SSA_NAME_VERSION (var
)];
190 sz
= unknown
[object_size_type
];
192 if (sz
!= unknown
[object_size_type
])
194 double_int dsz
= double_int::from_uhwi (sz
) - mem_ref_offset (pt_var
);
195 if (dsz
.is_negative ())
197 else if (dsz
.fits_uhwi ())
200 sz
= unknown
[object_size_type
];
203 if (sz
!= unknown
[object_size_type
] && sz
< offset_limit
)
204 pt_var_size
= size_int (sz
);
208 && host_integerp (DECL_SIZE_UNIT (pt_var
), 1)
209 && (unsigned HOST_WIDE_INT
)
210 tree_low_cst (DECL_SIZE_UNIT (pt_var
), 1) < offset_limit
)
211 pt_var_size
= DECL_SIZE_UNIT (pt_var
);
213 && TREE_CODE (pt_var
) == STRING_CST
214 && TYPE_SIZE_UNIT (TREE_TYPE (pt_var
))
215 && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (pt_var
)), 1)
216 && (unsigned HOST_WIDE_INT
)
217 tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (pt_var
)), 1)
219 pt_var_size
= TYPE_SIZE_UNIT (TREE_TYPE (pt_var
));
221 return unknown
[object_size_type
];
223 if (pt_var
!= TREE_OPERAND (ptr
, 0))
227 if (object_size_type
& 1)
229 var
= TREE_OPERAND (ptr
, 0);
232 && TREE_CODE (var
) != BIT_FIELD_REF
233 && TREE_CODE (var
) != COMPONENT_REF
234 && TREE_CODE (var
) != ARRAY_REF
235 && TREE_CODE (var
) != ARRAY_RANGE_REF
236 && TREE_CODE (var
) != REALPART_EXPR
237 && TREE_CODE (var
) != IMAGPART_EXPR
)
238 var
= TREE_OPERAND (var
, 0);
239 if (var
!= pt_var
&& TREE_CODE (var
) == ARRAY_REF
)
240 var
= TREE_OPERAND (var
, 0);
241 if (! TYPE_SIZE_UNIT (TREE_TYPE (var
))
242 || ! host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (var
)), 1)
244 && tree_int_cst_lt (pt_var_size
,
245 TYPE_SIZE_UNIT (TREE_TYPE (var
)))))
247 else if (var
!= pt_var
&& TREE_CODE (pt_var
) == MEM_REF
)
250 /* For &X->fld, compute object size only if fld isn't the last
251 field, as struct { int i; char c[1]; } is often used instead
252 of flexible array member. */
253 while (v
&& v
!= pt_var
)
254 switch (TREE_CODE (v
))
257 if (TYPE_SIZE_UNIT (TREE_TYPE (TREE_OPERAND (v
, 0)))
258 && TREE_CODE (TREE_OPERAND (v
, 1)) == INTEGER_CST
)
261 = TYPE_DOMAIN (TREE_TYPE (TREE_OPERAND (v
, 0)));
263 && TYPE_MAX_VALUE (domain
)
264 && TREE_CODE (TYPE_MAX_VALUE (domain
))
266 && tree_int_cst_lt (TREE_OPERAND (v
, 1),
267 TYPE_MAX_VALUE (domain
)))
273 v
= TREE_OPERAND (v
, 0);
280 if (TREE_CODE (TREE_TYPE (v
)) != ARRAY_TYPE
)
285 while (v
!= pt_var
&& TREE_CODE (v
) == COMPONENT_REF
)
286 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
288 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
292 v
= TREE_OPERAND (v
, 0);
293 if (TREE_CODE (v
) == COMPONENT_REF
294 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
297 tree fld_chain
= DECL_CHAIN (TREE_OPERAND (v
, 1));
298 for (; fld_chain
; fld_chain
= DECL_CHAIN (fld_chain
))
299 if (TREE_CODE (fld_chain
) == FIELD_DECL
)
307 v
= TREE_OPERAND (v
, 0);
309 while (v
!= pt_var
&& TREE_CODE (v
) == COMPONENT_REF
)
310 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
312 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
316 v
= TREE_OPERAND (v
, 0);
334 var_size
= TYPE_SIZE_UNIT (TREE_TYPE (var
));
335 else if (!pt_var_size
)
336 return unknown
[object_size_type
];
338 var_size
= pt_var_size
;
339 bytes
= compute_object_offset (TREE_OPERAND (ptr
, 0), var
);
340 if (bytes
!= error_mark_node
)
342 if (TREE_CODE (bytes
) == INTEGER_CST
343 && tree_int_cst_lt (var_size
, bytes
))
344 bytes
= size_zero_node
;
346 bytes
= size_binop (MINUS_EXPR
, var_size
, bytes
);
350 && TREE_CODE (pt_var
) == MEM_REF
351 && bytes
!= error_mark_node
)
353 tree bytes2
= compute_object_offset (TREE_OPERAND (ptr
, 0), pt_var
);
354 if (bytes2
!= error_mark_node
)
356 if (TREE_CODE (bytes2
) == INTEGER_CST
357 && tree_int_cst_lt (pt_var_size
, bytes2
))
358 bytes2
= size_zero_node
;
360 bytes2
= size_binop (MINUS_EXPR
, pt_var_size
, bytes2
);
361 bytes
= size_binop (MIN_EXPR
, bytes
, bytes2
);
365 else if (!pt_var_size
)
366 return unknown
[object_size_type
];
370 if (host_integerp (bytes
, 1))
371 return tree_low_cst (bytes
, 1);
373 return unknown
[object_size_type
];
377 /* Compute __builtin_object_size for CALL, which is a GIMPLE_CALL.
378 Handles various allocation calls. OBJECT_SIZE_TYPE is the second
379 argument from __builtin_object_size. If unknown, return
380 unknown[object_size_type]. */
382 static unsigned HOST_WIDE_INT
383 alloc_object_size (const_gimple call
, int object_size_type
)
385 tree callee
, bytes
= NULL_TREE
;
387 int arg1
= -1, arg2
= -1;
389 gcc_assert (is_gimple_call (call
));
391 callee
= gimple_call_fndecl (call
);
393 return unknown
[object_size_type
];
395 alloc_size
= lookup_attribute ("alloc_size", TYPE_ATTRIBUTES (TREE_TYPE(callee
)));
396 if (alloc_size
&& TREE_VALUE (alloc_size
))
398 tree p
= TREE_VALUE (alloc_size
);
400 arg1
= TREE_INT_CST_LOW (TREE_VALUE (p
))-1;
402 arg2
= TREE_INT_CST_LOW (TREE_VALUE (TREE_CHAIN (p
)))-1;
405 if (DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
406 switch (DECL_FUNCTION_CODE (callee
))
408 case BUILT_IN_CALLOC
:
411 case BUILT_IN_MALLOC
:
412 case BUILT_IN_ALLOCA
:
413 case BUILT_IN_ALLOCA_WITH_ALIGN
:
419 if (arg1
< 0 || arg1
>= (int)gimple_call_num_args (call
)
420 || TREE_CODE (gimple_call_arg (call
, arg1
)) != INTEGER_CST
422 && (arg2
>= (int)gimple_call_num_args (call
)
423 || TREE_CODE (gimple_call_arg (call
, arg2
)) != INTEGER_CST
)))
424 return unknown
[object_size_type
];
427 bytes
= size_binop (MULT_EXPR
,
428 fold_convert (sizetype
, gimple_call_arg (call
, arg1
)),
429 fold_convert (sizetype
, gimple_call_arg (call
, arg2
)));
431 bytes
= fold_convert (sizetype
, gimple_call_arg (call
, arg1
));
433 if (bytes
&& host_integerp (bytes
, 1))
434 return tree_low_cst (bytes
, 1);
436 return unknown
[object_size_type
];
440 /* If object size is propagated from one of function's arguments directly
441 to its return value, return that argument for GIMPLE_CALL statement CALL.
442 Otherwise return NULL. */
445 pass_through_call (const_gimple call
)
447 tree callee
= gimple_call_fndecl (call
);
450 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
451 switch (DECL_FUNCTION_CODE (callee
))
453 case BUILT_IN_MEMCPY
:
454 case BUILT_IN_MEMMOVE
:
455 case BUILT_IN_MEMSET
:
456 case BUILT_IN_STRCPY
:
457 case BUILT_IN_STRNCPY
:
458 case BUILT_IN_STRCAT
:
459 case BUILT_IN_STRNCAT
:
460 case BUILT_IN_MEMCPY_CHK
:
461 case BUILT_IN_MEMMOVE_CHK
:
462 case BUILT_IN_MEMSET_CHK
:
463 case BUILT_IN_STRCPY_CHK
:
464 case BUILT_IN_STRNCPY_CHK
:
465 case BUILT_IN_STPNCPY_CHK
:
466 case BUILT_IN_STRCAT_CHK
:
467 case BUILT_IN_STRNCAT_CHK
:
468 case BUILT_IN_ASSUME_ALIGNED
:
469 if (gimple_call_num_args (call
) >= 1)
470 return gimple_call_arg (call
, 0);
480 /* Compute __builtin_object_size value for PTR. OBJECT_SIZE_TYPE is the
481 second argument from __builtin_object_size. */
483 unsigned HOST_WIDE_INT
484 compute_builtin_object_size (tree ptr
, int object_size_type
)
486 gcc_assert (object_size_type
>= 0 && object_size_type
<= 3);
489 init_offset_limit ();
491 if (TREE_CODE (ptr
) == ADDR_EXPR
)
492 return addr_object_size (NULL
, ptr
, object_size_type
);
494 if (TREE_CODE (ptr
) == SSA_NAME
495 && POINTER_TYPE_P (TREE_TYPE (ptr
))
496 && object_sizes
[object_size_type
] != NULL
)
498 if (!bitmap_bit_p (computed
[object_size_type
], SSA_NAME_VERSION (ptr
)))
500 struct object_size_info osi
;
506 fprintf (dump_file
, "Computing %s %sobject size for ",
507 (object_size_type
& 2) ? "minimum" : "maximum",
508 (object_size_type
& 1) ? "sub" : "");
509 print_generic_expr (dump_file
, ptr
, dump_flags
);
510 fprintf (dump_file
, ":\n");
513 osi
.visited
= BITMAP_ALLOC (NULL
);
514 osi
.reexamine
= BITMAP_ALLOC (NULL
);
515 osi
.object_size_type
= object_size_type
;
520 /* First pass: walk UD chains, compute object sizes that
521 can be computed. osi.reexamine bitmap at the end will
522 contain what variables were found in dependency cycles
523 and therefore need to be reexamined. */
526 collect_object_sizes_for (&osi
, ptr
);
528 /* Second pass: keep recomputing object sizes of variables
529 that need reexamination, until no object sizes are
530 increased or all object sizes are computed. */
531 if (! bitmap_empty_p (osi
.reexamine
))
533 bitmap reexamine
= BITMAP_ALLOC (NULL
);
535 /* If looking for minimum instead of maximum object size,
536 detect cases where a pointer is increased in a loop.
537 Although even without this detection pass 2 would eventually
538 terminate, it could take a long time. If a pointer is
539 increasing this way, we need to assume 0 object size.
540 E.g. p = &buf[0]; while (cond) p = p + 4; */
541 if (object_size_type
& 2)
543 osi
.depths
= XCNEWVEC (unsigned int, num_ssa_names
);
544 osi
.stack
= XNEWVEC (unsigned int, num_ssa_names
);
547 /* collect_object_sizes_for is changing
548 osi.reexamine bitmap, so iterate over a copy. */
549 bitmap_copy (reexamine
, osi
.reexamine
);
550 EXECUTE_IF_SET_IN_BITMAP (reexamine
, 0, i
, bi
)
551 if (bitmap_bit_p (osi
.reexamine
, i
))
552 check_for_plus_in_loops (&osi
, ssa_name (i
));
565 /* collect_object_sizes_for is changing
566 osi.reexamine bitmap, so iterate over a copy. */
567 bitmap_copy (reexamine
, osi
.reexamine
);
568 EXECUTE_IF_SET_IN_BITMAP (reexamine
, 0, i
, bi
)
569 if (bitmap_bit_p (osi
.reexamine
, i
))
571 collect_object_sizes_for (&osi
, ssa_name (i
));
572 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
574 fprintf (dump_file
, "Reexamining ");
575 print_generic_expr (dump_file
, ssa_name (i
),
577 fprintf (dump_file
, "\n");
583 BITMAP_FREE (reexamine
);
585 EXECUTE_IF_SET_IN_BITMAP (osi
.reexamine
, 0, i
, bi
)
586 bitmap_set_bit (computed
[object_size_type
], i
);
588 /* Debugging dumps. */
591 EXECUTE_IF_SET_IN_BITMAP (osi
.visited
, 0, i
, bi
)
592 if (object_sizes
[object_size_type
][i
]
593 != unknown
[object_size_type
])
595 print_generic_expr (dump_file
, ssa_name (i
),
598 ": %s %sobject size "
599 HOST_WIDE_INT_PRINT_UNSIGNED
"\n",
600 (object_size_type
& 2) ? "minimum" : "maximum",
601 (object_size_type
& 1) ? "sub" : "",
602 object_sizes
[object_size_type
][i
]);
606 BITMAP_FREE (osi
.reexamine
);
607 BITMAP_FREE (osi
.visited
);
610 return object_sizes
[object_size_type
][SSA_NAME_VERSION (ptr
)];
613 return unknown
[object_size_type
];
616 /* Compute object_sizes for PTR, defined to VALUE, which is not an SSA_NAME. */
619 expr_object_size (struct object_size_info
*osi
, tree ptr
, tree value
)
621 int object_size_type
= osi
->object_size_type
;
622 unsigned int varno
= SSA_NAME_VERSION (ptr
);
623 unsigned HOST_WIDE_INT bytes
;
625 gcc_assert (object_sizes
[object_size_type
][varno
]
626 != unknown
[object_size_type
]);
627 gcc_assert (osi
->pass
== 0);
629 if (TREE_CODE (value
) == WITH_SIZE_EXPR
)
630 value
= TREE_OPERAND (value
, 0);
632 /* Pointer variables should have been handled by merge_object_sizes. */
633 gcc_assert (TREE_CODE (value
) != SSA_NAME
634 || !POINTER_TYPE_P (TREE_TYPE (value
)));
636 if (TREE_CODE (value
) == ADDR_EXPR
)
637 bytes
= addr_object_size (osi
, value
, object_size_type
);
639 bytes
= unknown
[object_size_type
];
641 if ((object_size_type
& 2) == 0)
643 if (object_sizes
[object_size_type
][varno
] < bytes
)
644 object_sizes
[object_size_type
][varno
] = bytes
;
648 if (object_sizes
[object_size_type
][varno
] > bytes
)
649 object_sizes
[object_size_type
][varno
] = bytes
;
654 /* Compute object_sizes for PTR, defined to the result of a call. */
657 call_object_size (struct object_size_info
*osi
, tree ptr
, gimple call
)
659 int object_size_type
= osi
->object_size_type
;
660 unsigned int varno
= SSA_NAME_VERSION (ptr
);
661 unsigned HOST_WIDE_INT bytes
;
663 gcc_assert (is_gimple_call (call
));
665 gcc_assert (object_sizes
[object_size_type
][varno
]
666 != unknown
[object_size_type
]);
667 gcc_assert (osi
->pass
== 0);
669 bytes
= alloc_object_size (call
, object_size_type
);
671 if ((object_size_type
& 2) == 0)
673 if (object_sizes
[object_size_type
][varno
] < bytes
)
674 object_sizes
[object_size_type
][varno
] = bytes
;
678 if (object_sizes
[object_size_type
][varno
] > bytes
)
679 object_sizes
[object_size_type
][varno
] = bytes
;
684 /* Compute object_sizes for PTR, defined to an unknown value. */
687 unknown_object_size (struct object_size_info
*osi
, tree ptr
)
689 int object_size_type
= osi
->object_size_type
;
690 unsigned int varno
= SSA_NAME_VERSION (ptr
);
691 unsigned HOST_WIDE_INT bytes
;
693 gcc_assert (object_sizes
[object_size_type
][varno
]
694 != unknown
[object_size_type
]);
695 gcc_assert (osi
->pass
== 0);
697 bytes
= unknown
[object_size_type
];
699 if ((object_size_type
& 2) == 0)
701 if (object_sizes
[object_size_type
][varno
] < bytes
)
702 object_sizes
[object_size_type
][varno
] = bytes
;
706 if (object_sizes
[object_size_type
][varno
] > bytes
)
707 object_sizes
[object_size_type
][varno
] = bytes
;
712 /* Merge object sizes of ORIG + OFFSET into DEST. Return true if
713 the object size might need reexamination later. */
716 merge_object_sizes (struct object_size_info
*osi
, tree dest
, tree orig
,
717 unsigned HOST_WIDE_INT offset
)
719 int object_size_type
= osi
->object_size_type
;
720 unsigned int varno
= SSA_NAME_VERSION (dest
);
721 unsigned HOST_WIDE_INT orig_bytes
;
723 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
725 if (offset
>= offset_limit
)
727 object_sizes
[object_size_type
][varno
] = unknown
[object_size_type
];
732 collect_object_sizes_for (osi
, orig
);
734 orig_bytes
= object_sizes
[object_size_type
][SSA_NAME_VERSION (orig
)];
735 if (orig_bytes
!= unknown
[object_size_type
])
736 orig_bytes
= (offset
> orig_bytes
)
737 ? (unsigned HOST_WIDE_INT
) 0 : orig_bytes
- offset
;
739 if ((object_size_type
& 2) == 0)
741 if (object_sizes
[object_size_type
][varno
] < orig_bytes
)
743 object_sizes
[object_size_type
][varno
] = orig_bytes
;
749 if (object_sizes
[object_size_type
][varno
] > orig_bytes
)
751 object_sizes
[object_size_type
][varno
] = orig_bytes
;
755 return bitmap_bit_p (osi
->reexamine
, SSA_NAME_VERSION (orig
));
759 /* Compute object_sizes for VAR, defined to the result of an assignment
760 with operator POINTER_PLUS_EXPR. Return true if the object size might
761 need reexamination later. */
764 plus_stmt_object_size (struct object_size_info
*osi
, tree var
, gimple stmt
)
766 int object_size_type
= osi
->object_size_type
;
767 unsigned int varno
= SSA_NAME_VERSION (var
);
768 unsigned HOST_WIDE_INT bytes
;
771 if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
773 op0
= gimple_assign_rhs1 (stmt
);
774 op1
= gimple_assign_rhs2 (stmt
);
776 else if (gimple_assign_rhs_code (stmt
) == ADDR_EXPR
)
778 tree rhs
= TREE_OPERAND (gimple_assign_rhs1 (stmt
), 0);
779 gcc_assert (TREE_CODE (rhs
) == MEM_REF
);
780 op0
= TREE_OPERAND (rhs
, 0);
781 op1
= TREE_OPERAND (rhs
, 1);
786 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
789 /* Handle PTR + OFFSET here. */
790 if (TREE_CODE (op1
) == INTEGER_CST
791 && (TREE_CODE (op0
) == SSA_NAME
792 || TREE_CODE (op0
) == ADDR_EXPR
))
794 if (! host_integerp (op1
, 1))
795 bytes
= unknown
[object_size_type
];
796 else if (TREE_CODE (op0
) == SSA_NAME
)
797 return merge_object_sizes (osi
, var
, op0
, tree_low_cst (op1
, 1));
800 unsigned HOST_WIDE_INT off
= tree_low_cst (op1
, 1);
802 /* op0 will be ADDR_EXPR here. */
803 bytes
= addr_object_size (osi
, op0
, object_size_type
);
804 if (bytes
== unknown
[object_size_type
])
806 else if (off
> offset_limit
)
807 bytes
= unknown
[object_size_type
];
808 else if (off
> bytes
)
815 bytes
= unknown
[object_size_type
];
817 if ((object_size_type
& 2) == 0)
819 if (object_sizes
[object_size_type
][varno
] < bytes
)
820 object_sizes
[object_size_type
][varno
] = bytes
;
824 if (object_sizes
[object_size_type
][varno
] > bytes
)
825 object_sizes
[object_size_type
][varno
] = bytes
;
831 /* Compute object_sizes for VAR, defined at STMT, which is
832 a COND_EXPR. Return true if the object size might need reexamination
836 cond_expr_object_size (struct object_size_info
*osi
, tree var
, gimple stmt
)
839 int object_size_type
= osi
->object_size_type
;
840 unsigned int varno
= SSA_NAME_VERSION (var
);
841 bool reexamine
= false;
843 gcc_assert (gimple_assign_rhs_code (stmt
) == COND_EXPR
);
845 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
848 then_
= gimple_assign_rhs2 (stmt
);
849 else_
= gimple_assign_rhs3 (stmt
);
851 if (TREE_CODE (then_
) == SSA_NAME
)
852 reexamine
|= merge_object_sizes (osi
, var
, then_
, 0);
854 expr_object_size (osi
, var
, then_
);
856 if (TREE_CODE (else_
) == SSA_NAME
)
857 reexamine
|= merge_object_sizes (osi
, var
, else_
, 0);
859 expr_object_size (osi
, var
, else_
);
864 /* Compute object sizes for VAR.
865 For ADDR_EXPR an object size is the number of remaining bytes
866 to the end of the object (where what is considered an object depends on
867 OSI->object_size_type).
868 For allocation GIMPLE_CALL like malloc or calloc object size is the size
870 For POINTER_PLUS_EXPR where second operand is a constant integer,
871 object size is object size of the first operand minus the constant.
872 If the constant is bigger than the number of remaining bytes until the
873 end of the object, object size is 0, but if it is instead a pointer
874 subtraction, object size is unknown[object_size_type].
875 To differentiate addition from subtraction, ADDR_EXPR returns
876 unknown[object_size_type] for all objects bigger than half of the address
877 space, and constants less than half of the address space are considered
878 addition, while bigger constants subtraction.
879 For a memcpy like GIMPLE_CALL that always returns one of its arguments, the
880 object size is object size of that argument.
881 Otherwise, object size is the maximum of object sizes of variables
882 that it might be set to. */
885 collect_object_sizes_for (struct object_size_info
*osi
, tree var
)
887 int object_size_type
= osi
->object_size_type
;
888 unsigned int varno
= SSA_NAME_VERSION (var
);
892 if (bitmap_bit_p (computed
[object_size_type
], varno
))
897 if (bitmap_set_bit (osi
->visited
, varno
))
899 object_sizes
[object_size_type
][varno
]
900 = (object_size_type
& 2) ? -1 : 0;
904 /* Found a dependency loop. Mark the variable for later
906 bitmap_set_bit (osi
->reexamine
, varno
);
907 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
909 fprintf (dump_file
, "Found a dependency loop at ");
910 print_generic_expr (dump_file
, var
, dump_flags
);
911 fprintf (dump_file
, "\n");
917 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
919 fprintf (dump_file
, "Visiting use-def links for ");
920 print_generic_expr (dump_file
, var
, dump_flags
);
921 fprintf (dump_file
, "\n");
924 stmt
= SSA_NAME_DEF_STMT (var
);
927 switch (gimple_code (stmt
))
931 tree rhs
= gimple_assign_rhs1 (stmt
);
932 if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
933 || (gimple_assign_rhs_code (stmt
) == ADDR_EXPR
934 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == MEM_REF
))
935 reexamine
= plus_stmt_object_size (osi
, var
, stmt
);
936 else if (gimple_assign_rhs_code (stmt
) == COND_EXPR
)
937 reexamine
= cond_expr_object_size (osi
, var
, stmt
);
938 else if (gimple_assign_single_p (stmt
)
939 || gimple_assign_unary_nop_p (stmt
))
941 if (TREE_CODE (rhs
) == SSA_NAME
942 && POINTER_TYPE_P (TREE_TYPE (rhs
)))
943 reexamine
= merge_object_sizes (osi
, var
, rhs
, 0);
945 expr_object_size (osi
, var
, rhs
);
948 unknown_object_size (osi
, var
);
954 tree arg
= pass_through_call (stmt
);
957 if (TREE_CODE (arg
) == SSA_NAME
958 && POINTER_TYPE_P (TREE_TYPE (arg
)))
959 reexamine
= merge_object_sizes (osi
, var
, arg
, 0);
961 expr_object_size (osi
, var
, arg
);
964 call_object_size (osi
, var
, stmt
);
969 /* Pointers defined by __asm__ statements can point anywhere. */
970 object_sizes
[object_size_type
][varno
] = unknown
[object_size_type
];
974 if (SSA_NAME_VAR (var
)
975 && TREE_CODE (SSA_NAME_VAR (var
)) == PARM_DECL
)
976 expr_object_size (osi
, var
, SSA_NAME_VAR (var
));
978 /* Uninitialized SSA names point nowhere. */
979 object_sizes
[object_size_type
][varno
] = unknown
[object_size_type
];
986 for (i
= 0; i
< gimple_phi_num_args (stmt
); i
++)
988 tree rhs
= gimple_phi_arg (stmt
, i
)->def
;
990 if (object_sizes
[object_size_type
][varno
]
991 == unknown
[object_size_type
])
994 if (TREE_CODE (rhs
) == SSA_NAME
)
995 reexamine
|= merge_object_sizes (osi
, var
, rhs
, 0);
996 else if (osi
->pass
== 0)
997 expr_object_size (osi
, var
, rhs
);
1007 || object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
1009 bitmap_set_bit (computed
[object_size_type
], varno
);
1010 bitmap_clear_bit (osi
->reexamine
, varno
);
1014 bitmap_set_bit (osi
->reexamine
, varno
);
1015 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1017 fprintf (dump_file
, "Need to reexamine ");
1018 print_generic_expr (dump_file
, var
, dump_flags
);
1019 fprintf (dump_file
, "\n");
1025 /* Helper function for check_for_plus_in_loops. Called recursively
1029 check_for_plus_in_loops_1 (struct object_size_info
*osi
, tree var
,
1032 gimple stmt
= SSA_NAME_DEF_STMT (var
);
1033 unsigned int varno
= SSA_NAME_VERSION (var
);
1035 if (osi
->depths
[varno
])
1037 if (osi
->depths
[varno
] != depth
)
1041 /* Found a loop involving pointer addition. */
1042 for (sp
= osi
->tos
; sp
> osi
->stack
; )
1045 bitmap_clear_bit (osi
->reexamine
, *sp
);
1046 bitmap_set_bit (computed
[osi
->object_size_type
], *sp
);
1047 object_sizes
[osi
->object_size_type
][*sp
] = 0;
1054 else if (! bitmap_bit_p (osi
->reexamine
, varno
))
1057 osi
->depths
[varno
] = depth
;
1058 *osi
->tos
++ = varno
;
1060 switch (gimple_code (stmt
))
1065 if ((gimple_assign_single_p (stmt
)
1066 || gimple_assign_unary_nop_p (stmt
))
1067 && TREE_CODE (gimple_assign_rhs1 (stmt
)) == SSA_NAME
)
1069 tree rhs
= gimple_assign_rhs1 (stmt
);
1071 check_for_plus_in_loops_1 (osi
, rhs
, depth
);
1073 else if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
1075 tree basevar
= gimple_assign_rhs1 (stmt
);
1076 tree cst
= gimple_assign_rhs2 (stmt
);
1078 gcc_assert (TREE_CODE (cst
) == INTEGER_CST
);
1080 check_for_plus_in_loops_1 (osi
, basevar
,
1081 depth
+ !integer_zerop (cst
));
1090 tree arg
= pass_through_call (stmt
);
1093 if (TREE_CODE (arg
) == SSA_NAME
)
1094 check_for_plus_in_loops_1 (osi
, arg
, depth
);
1105 for (i
= 0; i
< gimple_phi_num_args (stmt
); i
++)
1107 tree rhs
= gimple_phi_arg (stmt
, i
)->def
;
1109 if (TREE_CODE (rhs
) == SSA_NAME
)
1110 check_for_plus_in_loops_1 (osi
, rhs
, depth
);
1119 osi
->depths
[varno
] = 0;
1124 /* Check if some pointer we are computing object size of is being increased
1125 within a loop. If yes, assume all the SSA variables participating in
1126 that loop have minimum object sizes 0. */
1129 check_for_plus_in_loops (struct object_size_info
*osi
, tree var
)
1131 gimple stmt
= SSA_NAME_DEF_STMT (var
);
1133 /* NOTE: In the pre-tuples code, we handled a CALL_EXPR here,
1134 and looked for a POINTER_PLUS_EXPR in the pass-through
1135 argument, if any. In GIMPLE, however, such an expression
1136 is not a valid call operand. */
1138 if (is_gimple_assign (stmt
)
1139 && gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
1141 tree basevar
= gimple_assign_rhs1 (stmt
);
1142 tree cst
= gimple_assign_rhs2 (stmt
);
1144 gcc_assert (TREE_CODE (cst
) == INTEGER_CST
);
1146 if (integer_zerop (cst
))
1149 osi
->depths
[SSA_NAME_VERSION (basevar
)] = 1;
1150 *osi
->tos
++ = SSA_NAME_VERSION (basevar
);
1151 check_for_plus_in_loops_1 (osi
, var
, 2);
1152 osi
->depths
[SSA_NAME_VERSION (basevar
)] = 0;
1158 /* Initialize data structures for the object size computation. */
1161 init_object_sizes (void)
1163 int object_size_type
;
1165 if (object_sizes
[0])
1168 for (object_size_type
= 0; object_size_type
<= 3; object_size_type
++)
1170 object_sizes
[object_size_type
] = XNEWVEC (unsigned HOST_WIDE_INT
, num_ssa_names
);
1171 computed
[object_size_type
] = BITMAP_ALLOC (NULL
);
1174 init_offset_limit ();
1178 /* Destroy data structures after the object size computation. */
1181 fini_object_sizes (void)
1183 int object_size_type
;
1185 for (object_size_type
= 0; object_size_type
<= 3; object_size_type
++)
1187 free (object_sizes
[object_size_type
]);
1188 BITMAP_FREE (computed
[object_size_type
]);
1189 object_sizes
[object_size_type
] = NULL
;
1194 /* Simple pass to optimize all __builtin_object_size () builtins. */
1197 compute_object_sizes (void)
1202 gimple_stmt_iterator i
;
1203 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
1205 tree callee
, result
;
1206 gimple call
= gsi_stmt (i
);
1208 if (gimple_code (call
) != GIMPLE_CALL
)
1211 callee
= gimple_call_fndecl (call
);
1213 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
1214 || DECL_FUNCTION_CODE (callee
) != BUILT_IN_OBJECT_SIZE
)
1217 init_object_sizes ();
1218 result
= fold_call_stmt (call
, false);
1221 if (gimple_call_num_args (call
) == 2
1222 && POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
1224 tree ost
= gimple_call_arg (call
, 1);
1226 if (host_integerp (ost
, 1))
1228 unsigned HOST_WIDE_INT object_size_type
1229 = tree_low_cst (ost
, 1);
1231 if (object_size_type
< 2)
1232 result
= fold_convert (size_type_node
,
1233 integer_minus_one_node
);
1234 else if (object_size_type
< 4)
1235 result
= build_zero_cst (size_type_node
);
1243 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1245 fprintf (dump_file
, "Simplified\n ");
1246 print_gimple_stmt (dump_file
, call
, 0, dump_flags
);
1249 if (!update_call_from_tree (&i
, result
))
1252 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1254 fprintf (dump_file
, "to\n ");
1255 print_gimple_stmt (dump_file
, gsi_stmt (i
), 0, dump_flags
);
1256 fprintf (dump_file
, "\n");
1261 fini_object_sizes ();
1265 struct gimple_opt_pass pass_object_sizes
=
1270 OPTGROUP_NONE
, /* optinfo_flags */
1272 compute_object_sizes
, /* execute */
1275 0, /* static_pass_number */
1276 TV_NONE
, /* tv_id */
1277 PROP_cfg
| PROP_ssa
, /* properties_required */
1278 0, /* properties_provided */
1279 0, /* properties_destroyed */
1280 0, /* todo_flags_start */
1281 TODO_verify_ssa
/* todo_flags_finish */