1 /* __builtin_object_size (ptr, object_size_type) computation
2 Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
4 Contributed by Jakub Jelinek <jakub@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/>. */
24 #include "coretypes.h"
27 #include "diagnostic-core.h"
28 #include "gimple-pretty-print.h"
29 #include "tree-flow.h"
30 #include "tree-pass.h"
31 #include "tree-ssa-propagate.h"
33 struct object_size_info
36 bitmap visited
, reexamine
;
40 unsigned int *stack
, *tos
;
43 static unsigned HOST_WIDE_INT unknown
[4] = { -1, -1, 0, 0 };
45 static tree
compute_object_offset (const_tree
, const_tree
);
46 static unsigned HOST_WIDE_INT
addr_object_size (struct object_size_info
*,
48 static unsigned HOST_WIDE_INT
alloc_object_size (const_gimple
, int);
49 static tree
pass_through_call (const_gimple
);
50 static void collect_object_sizes_for (struct object_size_info
*, tree
);
51 static void expr_object_size (struct object_size_info
*, tree
, tree
);
52 static bool merge_object_sizes (struct object_size_info
*, tree
, tree
,
53 unsigned HOST_WIDE_INT
);
54 static bool plus_stmt_object_size (struct object_size_info
*, tree
, gimple
);
55 static bool cond_expr_object_size (struct object_size_info
*, tree
, gimple
);
56 static unsigned int compute_object_sizes (void);
57 static void init_offset_limit (void);
58 static void check_for_plus_in_loops (struct object_size_info
*, tree
);
59 static void check_for_plus_in_loops_1 (struct object_size_info
*, tree
,
62 /* object_sizes[0] is upper bound for number of bytes till the end of
64 object_sizes[1] is upper bound for number of bytes till the end of
65 the subobject (innermost array or field with address taken).
66 object_sizes[2] is lower bound for number of bytes till the end of
67 the object and object_sizes[3] lower bound for subobject. */
68 static unsigned HOST_WIDE_INT
*object_sizes
[4];
70 /* Bitmaps what object sizes have been computed already. */
71 static bitmap computed
[4];
73 /* Maximum value of offset we consider to be addition. */
74 static unsigned HOST_WIDE_INT offset_limit
;
77 /* Initialize OFFSET_LIMIT variable. */
79 init_offset_limit (void)
81 if (host_integerp (TYPE_MAX_VALUE (sizetype
), 1))
82 offset_limit
= tree_low_cst (TYPE_MAX_VALUE (sizetype
), 1);
89 /* Compute offset of EXPR within VAR. Return error_mark_node
93 compute_object_offset (const_tree expr
, const_tree var
)
95 enum tree_code code
= PLUS_EXPR
;
99 return size_zero_node
;
101 switch (TREE_CODE (expr
))
104 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
105 if (base
== error_mark_node
)
108 t
= TREE_OPERAND (expr
, 1);
109 off
= size_binop (PLUS_EXPR
, DECL_FIELD_OFFSET (t
),
110 size_int (tree_low_cst (DECL_FIELD_BIT_OFFSET (t
), 1)
116 case VIEW_CONVERT_EXPR
:
117 case NON_LVALUE_EXPR
:
118 return compute_object_offset (TREE_OPERAND (expr
, 0), var
);
121 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
122 if (base
== error_mark_node
)
125 off
= TYPE_SIZE_UNIT (TREE_TYPE (expr
));
129 base
= compute_object_offset (TREE_OPERAND (expr
, 0), var
);
130 if (base
== error_mark_node
)
133 t
= TREE_OPERAND (expr
, 1);
134 if (TREE_CODE (t
) == INTEGER_CST
&& tree_int_cst_sgn (t
) < 0)
137 t
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (t
), t
);
139 t
= fold_convert (sizetype
, t
);
140 off
= size_binop (MULT_EXPR
, TYPE_SIZE_UNIT (TREE_TYPE (expr
)), t
);
144 gcc_assert (TREE_CODE (TREE_OPERAND (expr
, 0)) == ADDR_EXPR
);
145 return double_int_to_tree (sizetype
, mem_ref_offset (expr
));
148 return error_mark_node
;
151 return size_binop (code
, base
, off
);
155 /* Compute __builtin_object_size for PTR, which is a ADDR_EXPR.
156 OBJECT_SIZE_TYPE is the second argument from __builtin_object_size.
157 If unknown, return unknown[object_size_type]. */
159 static unsigned HOST_WIDE_INT
160 addr_object_size (struct object_size_info
*osi
, const_tree ptr
,
161 int object_size_type
)
163 tree pt_var
, pt_var_size
= NULL_TREE
, var_size
, bytes
;
165 gcc_assert (TREE_CODE (ptr
) == ADDR_EXPR
);
167 pt_var
= TREE_OPERAND (ptr
, 0);
168 while (handled_component_p (pt_var
))
169 pt_var
= TREE_OPERAND (pt_var
, 0);
172 && TREE_CODE (pt_var
) == MEM_REF
)
174 unsigned HOST_WIDE_INT sz
;
176 if (!osi
|| (object_size_type
& 1) != 0
177 || TREE_CODE (TREE_OPERAND (pt_var
, 0)) != SSA_NAME
)
179 sz
= compute_builtin_object_size (TREE_OPERAND (pt_var
, 0),
180 object_size_type
& ~1);
184 tree var
= TREE_OPERAND (pt_var
, 0);
186 collect_object_sizes_for (osi
, var
);
187 if (bitmap_bit_p (computed
[object_size_type
],
188 SSA_NAME_VERSION (var
)))
189 sz
= object_sizes
[object_size_type
][SSA_NAME_VERSION (var
)];
191 sz
= unknown
[object_size_type
];
193 if (sz
!= unknown
[object_size_type
])
195 double_int dsz
= double_int_sub (uhwi_to_double_int (sz
),
196 mem_ref_offset (pt_var
));
197 if (double_int_negative_p (dsz
))
199 else if (double_int_fits_in_uhwi_p (dsz
))
200 sz
= double_int_to_uhwi (dsz
);
202 sz
= unknown
[object_size_type
];
205 if (sz
!= unknown
[object_size_type
] && sz
< offset_limit
)
206 pt_var_size
= size_int (sz
);
210 && host_integerp (DECL_SIZE_UNIT (pt_var
), 1)
211 && (unsigned HOST_WIDE_INT
)
212 tree_low_cst (DECL_SIZE_UNIT (pt_var
), 1) < offset_limit
)
213 pt_var_size
= DECL_SIZE_UNIT (pt_var
);
215 && TREE_CODE (pt_var
) == STRING_CST
216 && TYPE_SIZE_UNIT (TREE_TYPE (pt_var
))
217 && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (pt_var
)), 1)
218 && (unsigned HOST_WIDE_INT
)
219 tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (pt_var
)), 1)
221 pt_var_size
= TYPE_SIZE_UNIT (TREE_TYPE (pt_var
));
223 return unknown
[object_size_type
];
225 if (pt_var
!= TREE_OPERAND (ptr
, 0))
229 if (object_size_type
& 1)
231 var
= TREE_OPERAND (ptr
, 0);
234 && TREE_CODE (var
) != BIT_FIELD_REF
235 && TREE_CODE (var
) != COMPONENT_REF
236 && TREE_CODE (var
) != ARRAY_REF
237 && TREE_CODE (var
) != ARRAY_RANGE_REF
238 && TREE_CODE (var
) != REALPART_EXPR
239 && TREE_CODE (var
) != IMAGPART_EXPR
)
240 var
= TREE_OPERAND (var
, 0);
241 if (var
!= pt_var
&& TREE_CODE (var
) == ARRAY_REF
)
242 var
= TREE_OPERAND (var
, 0);
243 if (! TYPE_SIZE_UNIT (TREE_TYPE (var
))
244 || ! host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (var
)), 1)
246 && tree_int_cst_lt (pt_var_size
,
247 TYPE_SIZE_UNIT (TREE_TYPE (var
)))))
249 else if (var
!= pt_var
&& TREE_CODE (pt_var
) == MEM_REF
)
252 /* For &X->fld, compute object size only if fld isn't the last
253 field, as struct { int i; char c[1]; } is often used instead
254 of flexible array member. */
255 while (v
&& v
!= pt_var
)
256 switch (TREE_CODE (v
))
259 if (TYPE_SIZE_UNIT (TREE_TYPE (TREE_OPERAND (v
, 0)))
260 && TREE_CODE (TREE_OPERAND (v
, 1)) == INTEGER_CST
)
263 = TYPE_DOMAIN (TREE_TYPE (TREE_OPERAND (v
, 0)));
265 && TYPE_MAX_VALUE (domain
)
266 && TREE_CODE (TYPE_MAX_VALUE (domain
))
268 && tree_int_cst_lt (TREE_OPERAND (v
, 1),
269 TYPE_MAX_VALUE (domain
)))
275 v
= TREE_OPERAND (v
, 0);
282 if (TREE_CODE (TREE_TYPE (v
)) != ARRAY_TYPE
)
287 while (v
!= pt_var
&& TREE_CODE (v
) == COMPONENT_REF
)
288 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
290 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
294 v
= TREE_OPERAND (v
, 0);
295 if (TREE_CODE (v
) == COMPONENT_REF
296 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
299 tree fld_chain
= DECL_CHAIN (TREE_OPERAND (v
, 1));
300 for (; fld_chain
; fld_chain
= DECL_CHAIN (fld_chain
))
301 if (TREE_CODE (fld_chain
) == FIELD_DECL
)
309 v
= TREE_OPERAND (v
, 0);
311 while (v
!= pt_var
&& TREE_CODE (v
) == COMPONENT_REF
)
312 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
314 && TREE_CODE (TREE_TYPE (TREE_OPERAND (v
, 0)))
318 v
= TREE_OPERAND (v
, 0);
336 var_size
= TYPE_SIZE_UNIT (TREE_TYPE (var
));
337 else if (!pt_var_size
)
338 return unknown
[object_size_type
];
340 var_size
= pt_var_size
;
341 bytes
= compute_object_offset (TREE_OPERAND (ptr
, 0), var
);
342 if (bytes
!= error_mark_node
)
344 if (TREE_CODE (bytes
) == INTEGER_CST
345 && tree_int_cst_lt (var_size
, bytes
))
346 bytes
= size_zero_node
;
348 bytes
= size_binop (MINUS_EXPR
, var_size
, bytes
);
352 && TREE_CODE (pt_var
) == MEM_REF
353 && bytes
!= error_mark_node
)
355 tree bytes2
= compute_object_offset (TREE_OPERAND (ptr
, 0), pt_var
);
356 if (bytes2
!= error_mark_node
)
358 if (TREE_CODE (bytes2
) == INTEGER_CST
359 && tree_int_cst_lt (pt_var_size
, bytes2
))
360 bytes2
= size_zero_node
;
362 bytes2
= size_binop (MINUS_EXPR
, pt_var_size
, bytes2
);
363 bytes
= size_binop (MIN_EXPR
, bytes
, bytes2
);
367 else if (!pt_var_size
)
368 return unknown
[object_size_type
];
372 if (host_integerp (bytes
, 1))
373 return tree_low_cst (bytes
, 1);
375 return unknown
[object_size_type
];
379 /* Compute __builtin_object_size for CALL, which is a GIMPLE_CALL.
380 Handles various allocation calls. OBJECT_SIZE_TYPE is the second
381 argument from __builtin_object_size. If unknown, return
382 unknown[object_size_type]. */
384 static unsigned HOST_WIDE_INT
385 alloc_object_size (const_gimple call
, int object_size_type
)
387 tree callee
, bytes
= NULL_TREE
;
389 int arg1
= -1, arg2
= -1;
391 gcc_assert (is_gimple_call (call
));
393 callee
= gimple_call_fndecl (call
);
395 return unknown
[object_size_type
];
397 alloc_size
= lookup_attribute ("alloc_size", TYPE_ATTRIBUTES (TREE_TYPE(callee
)));
398 if (alloc_size
&& TREE_VALUE (alloc_size
))
400 tree p
= TREE_VALUE (alloc_size
);
402 arg1
= TREE_INT_CST_LOW (TREE_VALUE (p
))-1;
404 arg2
= TREE_INT_CST_LOW (TREE_VALUE (TREE_CHAIN (p
)))-1;
407 if (DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
408 switch (DECL_FUNCTION_CODE (callee
))
410 case BUILT_IN_CALLOC
:
413 case BUILT_IN_MALLOC
:
414 case BUILT_IN_ALLOCA
:
415 case BUILT_IN_ALLOCA_WITH_ALIGN
:
421 if (arg1
< 0 || arg1
>= (int)gimple_call_num_args (call
)
422 || TREE_CODE (gimple_call_arg (call
, arg1
)) != INTEGER_CST
424 && (arg2
>= (int)gimple_call_num_args (call
)
425 || TREE_CODE (gimple_call_arg (call
, arg2
)) != INTEGER_CST
)))
426 return unknown
[object_size_type
];
429 bytes
= size_binop (MULT_EXPR
,
430 fold_convert (sizetype
, gimple_call_arg (call
, arg1
)),
431 fold_convert (sizetype
, gimple_call_arg (call
, arg2
)));
433 bytes
= fold_convert (sizetype
, gimple_call_arg (call
, arg1
));
435 if (bytes
&& host_integerp (bytes
, 1))
436 return tree_low_cst (bytes
, 1);
438 return unknown
[object_size_type
];
442 /* If object size is propagated from one of function's arguments directly
443 to its return value, return that argument for GIMPLE_CALL statement CALL.
444 Otherwise return NULL. */
447 pass_through_call (const_gimple call
)
449 tree callee
= gimple_call_fndecl (call
);
452 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
)
453 switch (DECL_FUNCTION_CODE (callee
))
455 case BUILT_IN_MEMCPY
:
456 case BUILT_IN_MEMMOVE
:
457 case BUILT_IN_MEMSET
:
458 case BUILT_IN_STRCPY
:
459 case BUILT_IN_STRNCPY
:
460 case BUILT_IN_STRCAT
:
461 case BUILT_IN_STRNCAT
:
462 case BUILT_IN_MEMCPY_CHK
:
463 case BUILT_IN_MEMMOVE_CHK
:
464 case BUILT_IN_MEMSET_CHK
:
465 case BUILT_IN_STRCPY_CHK
:
466 case BUILT_IN_STRNCPY_CHK
:
467 case BUILT_IN_STPNCPY_CHK
:
468 case BUILT_IN_STRCAT_CHK
:
469 case BUILT_IN_STRNCAT_CHK
:
470 case BUILT_IN_ASSUME_ALIGNED
:
471 if (gimple_call_num_args (call
) >= 1)
472 return gimple_call_arg (call
, 0);
482 /* Compute __builtin_object_size value for PTR. OBJECT_SIZE_TYPE is the
483 second argument from __builtin_object_size. */
485 unsigned HOST_WIDE_INT
486 compute_builtin_object_size (tree ptr
, int object_size_type
)
488 gcc_assert (object_size_type
>= 0 && object_size_type
<= 3);
491 init_offset_limit ();
493 if (TREE_CODE (ptr
) == ADDR_EXPR
)
494 return addr_object_size (NULL
, ptr
, object_size_type
);
496 if (TREE_CODE (ptr
) == SSA_NAME
497 && POINTER_TYPE_P (TREE_TYPE (ptr
))
498 && object_sizes
[object_size_type
] != NULL
)
500 if (!bitmap_bit_p (computed
[object_size_type
], SSA_NAME_VERSION (ptr
)))
502 struct object_size_info osi
;
508 fprintf (dump_file
, "Computing %s %sobject size for ",
509 (object_size_type
& 2) ? "minimum" : "maximum",
510 (object_size_type
& 1) ? "sub" : "");
511 print_generic_expr (dump_file
, ptr
, dump_flags
);
512 fprintf (dump_file
, ":\n");
515 osi
.visited
= BITMAP_ALLOC (NULL
);
516 osi
.reexamine
= BITMAP_ALLOC (NULL
);
517 osi
.object_size_type
= object_size_type
;
522 /* First pass: walk UD chains, compute object sizes that
523 can be computed. osi.reexamine bitmap at the end will
524 contain what variables were found in dependency cycles
525 and therefore need to be reexamined. */
528 collect_object_sizes_for (&osi
, ptr
);
530 /* Second pass: keep recomputing object sizes of variables
531 that need reexamination, until no object sizes are
532 increased or all object sizes are computed. */
533 if (! bitmap_empty_p (osi
.reexamine
))
535 bitmap reexamine
= BITMAP_ALLOC (NULL
);
537 /* If looking for minimum instead of maximum object size,
538 detect cases where a pointer is increased in a loop.
539 Although even without this detection pass 2 would eventually
540 terminate, it could take a long time. If a pointer is
541 increasing this way, we need to assume 0 object size.
542 E.g. p = &buf[0]; while (cond) p = p + 4; */
543 if (object_size_type
& 2)
545 osi
.depths
= XCNEWVEC (unsigned int, num_ssa_names
);
546 osi
.stack
= XNEWVEC (unsigned int, num_ssa_names
);
549 /* collect_object_sizes_for is changing
550 osi.reexamine bitmap, so iterate over a copy. */
551 bitmap_copy (reexamine
, osi
.reexamine
);
552 EXECUTE_IF_SET_IN_BITMAP (reexamine
, 0, i
, bi
)
553 if (bitmap_bit_p (osi
.reexamine
, i
))
554 check_for_plus_in_loops (&osi
, ssa_name (i
));
567 /* collect_object_sizes_for is changing
568 osi.reexamine bitmap, so iterate over a copy. */
569 bitmap_copy (reexamine
, osi
.reexamine
);
570 EXECUTE_IF_SET_IN_BITMAP (reexamine
, 0, i
, bi
)
571 if (bitmap_bit_p (osi
.reexamine
, i
))
573 collect_object_sizes_for (&osi
, ssa_name (i
));
574 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
576 fprintf (dump_file
, "Reexamining ");
577 print_generic_expr (dump_file
, ssa_name (i
),
579 fprintf (dump_file
, "\n");
585 BITMAP_FREE (reexamine
);
587 EXECUTE_IF_SET_IN_BITMAP (osi
.reexamine
, 0, i
, bi
)
588 bitmap_set_bit (computed
[object_size_type
], i
);
590 /* Debugging dumps. */
593 EXECUTE_IF_SET_IN_BITMAP (osi
.visited
, 0, i
, bi
)
594 if (object_sizes
[object_size_type
][i
]
595 != unknown
[object_size_type
])
597 print_generic_expr (dump_file
, ssa_name (i
),
600 ": %s %sobject size "
601 HOST_WIDE_INT_PRINT_UNSIGNED
"\n",
602 (object_size_type
& 2) ? "minimum" : "maximum",
603 (object_size_type
& 1) ? "sub" : "",
604 object_sizes
[object_size_type
][i
]);
608 BITMAP_FREE (osi
.reexamine
);
609 BITMAP_FREE (osi
.visited
);
612 return object_sizes
[object_size_type
][SSA_NAME_VERSION (ptr
)];
615 return unknown
[object_size_type
];
618 /* Compute object_sizes for PTR, defined to VALUE, which is not an SSA_NAME. */
621 expr_object_size (struct object_size_info
*osi
, tree ptr
, tree value
)
623 int object_size_type
= osi
->object_size_type
;
624 unsigned int varno
= SSA_NAME_VERSION (ptr
);
625 unsigned HOST_WIDE_INT bytes
;
627 gcc_assert (object_sizes
[object_size_type
][varno
]
628 != unknown
[object_size_type
]);
629 gcc_assert (osi
->pass
== 0);
631 if (TREE_CODE (value
) == WITH_SIZE_EXPR
)
632 value
= TREE_OPERAND (value
, 0);
634 /* Pointer variables should have been handled by merge_object_sizes. */
635 gcc_assert (TREE_CODE (value
) != SSA_NAME
636 || !POINTER_TYPE_P (TREE_TYPE (value
)));
638 if (TREE_CODE (value
) == ADDR_EXPR
)
639 bytes
= addr_object_size (osi
, value
, object_size_type
);
641 bytes
= unknown
[object_size_type
];
643 if ((object_size_type
& 2) == 0)
645 if (object_sizes
[object_size_type
][varno
] < bytes
)
646 object_sizes
[object_size_type
][varno
] = bytes
;
650 if (object_sizes
[object_size_type
][varno
] > bytes
)
651 object_sizes
[object_size_type
][varno
] = bytes
;
656 /* Compute object_sizes for PTR, defined to the result of a call. */
659 call_object_size (struct object_size_info
*osi
, tree ptr
, gimple call
)
661 int object_size_type
= osi
->object_size_type
;
662 unsigned int varno
= SSA_NAME_VERSION (ptr
);
663 unsigned HOST_WIDE_INT bytes
;
665 gcc_assert (is_gimple_call (call
));
667 gcc_assert (object_sizes
[object_size_type
][varno
]
668 != unknown
[object_size_type
]);
669 gcc_assert (osi
->pass
== 0);
671 bytes
= alloc_object_size (call
, object_size_type
);
673 if ((object_size_type
& 2) == 0)
675 if (object_sizes
[object_size_type
][varno
] < bytes
)
676 object_sizes
[object_size_type
][varno
] = bytes
;
680 if (object_sizes
[object_size_type
][varno
] > bytes
)
681 object_sizes
[object_size_type
][varno
] = bytes
;
686 /* Compute object_sizes for PTR, defined to an unknown value. */
689 unknown_object_size (struct object_size_info
*osi
, tree ptr
)
691 int object_size_type
= osi
->object_size_type
;
692 unsigned int varno
= SSA_NAME_VERSION (ptr
);
693 unsigned HOST_WIDE_INT bytes
;
695 gcc_assert (object_sizes
[object_size_type
][varno
]
696 != unknown
[object_size_type
]);
697 gcc_assert (osi
->pass
== 0);
699 bytes
= unknown
[object_size_type
];
701 if ((object_size_type
& 2) == 0)
703 if (object_sizes
[object_size_type
][varno
] < bytes
)
704 object_sizes
[object_size_type
][varno
] = bytes
;
708 if (object_sizes
[object_size_type
][varno
] > bytes
)
709 object_sizes
[object_size_type
][varno
] = bytes
;
714 /* Merge object sizes of ORIG + OFFSET into DEST. Return true if
715 the object size might need reexamination later. */
718 merge_object_sizes (struct object_size_info
*osi
, tree dest
, tree orig
,
719 unsigned HOST_WIDE_INT offset
)
721 int object_size_type
= osi
->object_size_type
;
722 unsigned int varno
= SSA_NAME_VERSION (dest
);
723 unsigned HOST_WIDE_INT orig_bytes
;
725 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
727 if (offset
>= offset_limit
)
729 object_sizes
[object_size_type
][varno
] = unknown
[object_size_type
];
734 collect_object_sizes_for (osi
, orig
);
736 orig_bytes
= object_sizes
[object_size_type
][SSA_NAME_VERSION (orig
)];
737 if (orig_bytes
!= unknown
[object_size_type
])
738 orig_bytes
= (offset
> orig_bytes
)
739 ? (unsigned HOST_WIDE_INT
) 0 : orig_bytes
- offset
;
741 if ((object_size_type
& 2) == 0)
743 if (object_sizes
[object_size_type
][varno
] < orig_bytes
)
745 object_sizes
[object_size_type
][varno
] = orig_bytes
;
751 if (object_sizes
[object_size_type
][varno
] > orig_bytes
)
753 object_sizes
[object_size_type
][varno
] = orig_bytes
;
757 return bitmap_bit_p (osi
->reexamine
, SSA_NAME_VERSION (orig
));
761 /* Compute object_sizes for VAR, defined to the result of an assignment
762 with operator POINTER_PLUS_EXPR. Return true if the object size might
763 need reexamination later. */
766 plus_stmt_object_size (struct object_size_info
*osi
, tree var
, gimple stmt
)
768 int object_size_type
= osi
->object_size_type
;
769 unsigned int varno
= SSA_NAME_VERSION (var
);
770 unsigned HOST_WIDE_INT bytes
;
773 if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
775 op0
= gimple_assign_rhs1 (stmt
);
776 op1
= gimple_assign_rhs2 (stmt
);
778 else if (gimple_assign_rhs_code (stmt
) == ADDR_EXPR
)
780 tree rhs
= TREE_OPERAND (gimple_assign_rhs1 (stmt
), 0);
781 gcc_assert (TREE_CODE (rhs
) == MEM_REF
);
782 op0
= TREE_OPERAND (rhs
, 0);
783 op1
= TREE_OPERAND (rhs
, 1);
788 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
791 /* Handle PTR + OFFSET here. */
792 if (TREE_CODE (op1
) == INTEGER_CST
793 && (TREE_CODE (op0
) == SSA_NAME
794 || TREE_CODE (op0
) == ADDR_EXPR
))
796 if (! host_integerp (op1
, 1))
797 bytes
= unknown
[object_size_type
];
798 else if (TREE_CODE (op0
) == SSA_NAME
)
799 return merge_object_sizes (osi
, var
, op0
, tree_low_cst (op1
, 1));
802 unsigned HOST_WIDE_INT off
= tree_low_cst (op1
, 1);
804 /* op0 will be ADDR_EXPR here. */
805 bytes
= addr_object_size (osi
, op0
, object_size_type
);
806 if (bytes
== unknown
[object_size_type
])
808 else if (off
> offset_limit
)
809 bytes
= unknown
[object_size_type
];
810 else if (off
> bytes
)
817 bytes
= unknown
[object_size_type
];
819 if ((object_size_type
& 2) == 0)
821 if (object_sizes
[object_size_type
][varno
] < bytes
)
822 object_sizes
[object_size_type
][varno
] = bytes
;
826 if (object_sizes
[object_size_type
][varno
] > bytes
)
827 object_sizes
[object_size_type
][varno
] = bytes
;
833 /* Compute object_sizes for VAR, defined at STMT, which is
834 a COND_EXPR. Return true if the object size might need reexamination
838 cond_expr_object_size (struct object_size_info
*osi
, tree var
, gimple stmt
)
841 int object_size_type
= osi
->object_size_type
;
842 unsigned int varno
= SSA_NAME_VERSION (var
);
843 bool reexamine
= false;
845 gcc_assert (gimple_assign_rhs_code (stmt
) == COND_EXPR
);
847 if (object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
850 then_
= gimple_assign_rhs2 (stmt
);
851 else_
= gimple_assign_rhs3 (stmt
);
853 if (TREE_CODE (then_
) == SSA_NAME
)
854 reexamine
|= merge_object_sizes (osi
, var
, then_
, 0);
856 expr_object_size (osi
, var
, then_
);
858 if (TREE_CODE (else_
) == SSA_NAME
)
859 reexamine
|= merge_object_sizes (osi
, var
, else_
, 0);
861 expr_object_size (osi
, var
, else_
);
866 /* Compute object sizes for VAR.
867 For ADDR_EXPR an object size is the number of remaining bytes
868 to the end of the object (where what is considered an object depends on
869 OSI->object_size_type).
870 For allocation GIMPLE_CALL like malloc or calloc object size is the size
872 For POINTER_PLUS_EXPR where second operand is a constant integer,
873 object size is object size of the first operand minus the constant.
874 If the constant is bigger than the number of remaining bytes until the
875 end of the object, object size is 0, but if it is instead a pointer
876 subtraction, object size is unknown[object_size_type].
877 To differentiate addition from subtraction, ADDR_EXPR returns
878 unknown[object_size_type] for all objects bigger than half of the address
879 space, and constants less than half of the address space are considered
880 addition, while bigger constants subtraction.
881 For a memcpy like GIMPLE_CALL that always returns one of its arguments, the
882 object size is object size of that argument.
883 Otherwise, object size is the maximum of object sizes of variables
884 that it might be set to. */
887 collect_object_sizes_for (struct object_size_info
*osi
, tree var
)
889 int object_size_type
= osi
->object_size_type
;
890 unsigned int varno
= SSA_NAME_VERSION (var
);
894 if (bitmap_bit_p (computed
[object_size_type
], varno
))
899 if (bitmap_set_bit (osi
->visited
, varno
))
901 object_sizes
[object_size_type
][varno
]
902 = (object_size_type
& 2) ? -1 : 0;
906 /* Found a dependency loop. Mark the variable for later
908 bitmap_set_bit (osi
->reexamine
, varno
);
909 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
911 fprintf (dump_file
, "Found a dependency loop at ");
912 print_generic_expr (dump_file
, var
, dump_flags
);
913 fprintf (dump_file
, "\n");
919 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
921 fprintf (dump_file
, "Visiting use-def links for ");
922 print_generic_expr (dump_file
, var
, dump_flags
);
923 fprintf (dump_file
, "\n");
926 stmt
= SSA_NAME_DEF_STMT (var
);
929 switch (gimple_code (stmt
))
933 tree rhs
= gimple_assign_rhs1 (stmt
);
934 if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
935 || (gimple_assign_rhs_code (stmt
) == ADDR_EXPR
936 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == MEM_REF
))
937 reexamine
= plus_stmt_object_size (osi
, var
, stmt
);
938 else if (gimple_assign_rhs_code (stmt
) == COND_EXPR
)
939 reexamine
= cond_expr_object_size (osi
, var
, stmt
);
940 else if (gimple_assign_single_p (stmt
)
941 || gimple_assign_unary_nop_p (stmt
))
943 if (TREE_CODE (rhs
) == SSA_NAME
944 && POINTER_TYPE_P (TREE_TYPE (rhs
)))
945 reexamine
= merge_object_sizes (osi
, var
, rhs
, 0);
947 expr_object_size (osi
, var
, rhs
);
950 unknown_object_size (osi
, var
);
956 tree arg
= pass_through_call (stmt
);
959 if (TREE_CODE (arg
) == SSA_NAME
960 && POINTER_TYPE_P (TREE_TYPE (arg
)))
961 reexamine
= merge_object_sizes (osi
, var
, arg
, 0);
963 expr_object_size (osi
, var
, arg
);
966 call_object_size (osi
, var
, stmt
);
971 /* Pointers defined by __asm__ statements can point anywhere. */
972 object_sizes
[object_size_type
][varno
] = unknown
[object_size_type
];
977 tree decl
= SSA_NAME_VAR (var
);
979 if (TREE_CODE (decl
) != PARM_DECL
&& DECL_INITIAL (decl
))
980 expr_object_size (osi
, var
, DECL_INITIAL (decl
));
982 expr_object_size (osi
, var
, decl
);
990 for (i
= 0; i
< gimple_phi_num_args (stmt
); i
++)
992 tree rhs
= gimple_phi_arg (stmt
, i
)->def
;
994 if (object_sizes
[object_size_type
][varno
]
995 == unknown
[object_size_type
])
998 if (TREE_CODE (rhs
) == SSA_NAME
)
999 reexamine
|= merge_object_sizes (osi
, var
, rhs
, 0);
1000 else if (osi
->pass
== 0)
1001 expr_object_size (osi
, var
, rhs
);
1011 || object_sizes
[object_size_type
][varno
] == unknown
[object_size_type
])
1013 bitmap_set_bit (computed
[object_size_type
], varno
);
1014 bitmap_clear_bit (osi
->reexamine
, varno
);
1018 bitmap_set_bit (osi
->reexamine
, varno
);
1019 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1021 fprintf (dump_file
, "Need to reexamine ");
1022 print_generic_expr (dump_file
, var
, dump_flags
);
1023 fprintf (dump_file
, "\n");
1029 /* Helper function for check_for_plus_in_loops. Called recursively
1033 check_for_plus_in_loops_1 (struct object_size_info
*osi
, tree var
,
1036 gimple stmt
= SSA_NAME_DEF_STMT (var
);
1037 unsigned int varno
= SSA_NAME_VERSION (var
);
1039 if (osi
->depths
[varno
])
1041 if (osi
->depths
[varno
] != depth
)
1045 /* Found a loop involving pointer addition. */
1046 for (sp
= osi
->tos
; sp
> osi
->stack
; )
1049 bitmap_clear_bit (osi
->reexamine
, *sp
);
1050 bitmap_set_bit (computed
[osi
->object_size_type
], *sp
);
1051 object_sizes
[osi
->object_size_type
][*sp
] = 0;
1058 else if (! bitmap_bit_p (osi
->reexamine
, varno
))
1061 osi
->depths
[varno
] = depth
;
1062 *osi
->tos
++ = varno
;
1064 switch (gimple_code (stmt
))
1069 if ((gimple_assign_single_p (stmt
)
1070 || gimple_assign_unary_nop_p (stmt
))
1071 && TREE_CODE (gimple_assign_rhs1 (stmt
)) == SSA_NAME
)
1073 tree rhs
= gimple_assign_rhs1 (stmt
);
1075 check_for_plus_in_loops_1 (osi
, rhs
, depth
);
1077 else if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
1079 tree basevar
= gimple_assign_rhs1 (stmt
);
1080 tree cst
= gimple_assign_rhs2 (stmt
);
1082 gcc_assert (TREE_CODE (cst
) == INTEGER_CST
);
1084 check_for_plus_in_loops_1 (osi
, basevar
,
1085 depth
+ !integer_zerop (cst
));
1094 tree arg
= pass_through_call (stmt
);
1097 if (TREE_CODE (arg
) == SSA_NAME
)
1098 check_for_plus_in_loops_1 (osi
, arg
, depth
);
1109 for (i
= 0; i
< gimple_phi_num_args (stmt
); i
++)
1111 tree rhs
= gimple_phi_arg (stmt
, i
)->def
;
1113 if (TREE_CODE (rhs
) == SSA_NAME
)
1114 check_for_plus_in_loops_1 (osi
, rhs
, depth
);
1123 osi
->depths
[varno
] = 0;
1128 /* Check if some pointer we are computing object size of is being increased
1129 within a loop. If yes, assume all the SSA variables participating in
1130 that loop have minimum object sizes 0. */
1133 check_for_plus_in_loops (struct object_size_info
*osi
, tree var
)
1135 gimple stmt
= SSA_NAME_DEF_STMT (var
);
1137 /* NOTE: In the pre-tuples code, we handled a CALL_EXPR here,
1138 and looked for a POINTER_PLUS_EXPR in the pass-through
1139 argument, if any. In GIMPLE, however, such an expression
1140 is not a valid call operand. */
1142 if (is_gimple_assign (stmt
)
1143 && gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
)
1145 tree basevar
= gimple_assign_rhs1 (stmt
);
1146 tree cst
= gimple_assign_rhs2 (stmt
);
1148 gcc_assert (TREE_CODE (cst
) == INTEGER_CST
);
1150 if (integer_zerop (cst
))
1153 osi
->depths
[SSA_NAME_VERSION (basevar
)] = 1;
1154 *osi
->tos
++ = SSA_NAME_VERSION (basevar
);
1155 check_for_plus_in_loops_1 (osi
, var
, 2);
1156 osi
->depths
[SSA_NAME_VERSION (basevar
)] = 0;
1162 /* Initialize data structures for the object size computation. */
1165 init_object_sizes (void)
1167 int object_size_type
;
1169 if (object_sizes
[0])
1172 for (object_size_type
= 0; object_size_type
<= 3; object_size_type
++)
1174 object_sizes
[object_size_type
] = XNEWVEC (unsigned HOST_WIDE_INT
, num_ssa_names
);
1175 computed
[object_size_type
] = BITMAP_ALLOC (NULL
);
1178 init_offset_limit ();
1182 /* Destroy data structures after the object size computation. */
1185 fini_object_sizes (void)
1187 int object_size_type
;
1189 for (object_size_type
= 0; object_size_type
<= 3; object_size_type
++)
1191 free (object_sizes
[object_size_type
]);
1192 BITMAP_FREE (computed
[object_size_type
]);
1193 object_sizes
[object_size_type
] = NULL
;
1198 /* Simple pass to optimize all __builtin_object_size () builtins. */
1201 compute_object_sizes (void)
1206 gimple_stmt_iterator i
;
1207 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
1209 tree callee
, result
;
1210 gimple call
= gsi_stmt (i
);
1212 if (gimple_code (call
) != GIMPLE_CALL
)
1215 callee
= gimple_call_fndecl (call
);
1217 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
1218 || DECL_FUNCTION_CODE (callee
) != BUILT_IN_OBJECT_SIZE
)
1221 init_object_sizes ();
1222 result
= fold_call_stmt (call
, false);
1225 if (gimple_call_num_args (call
) == 2
1226 && POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
1228 tree ost
= gimple_call_arg (call
, 1);
1230 if (host_integerp (ost
, 1))
1232 unsigned HOST_WIDE_INT object_size_type
1233 = tree_low_cst (ost
, 1);
1235 if (object_size_type
< 2)
1236 result
= fold_convert (size_type_node
,
1237 integer_minus_one_node
);
1238 else if (object_size_type
< 4)
1239 result
= build_zero_cst (size_type_node
);
1247 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1249 fprintf (dump_file
, "Simplified\n ");
1250 print_gimple_stmt (dump_file
, call
, 0, dump_flags
);
1253 if (!update_call_from_tree (&i
, result
))
1256 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1258 fprintf (dump_file
, "to\n ");
1259 print_gimple_stmt (dump_file
, gsi_stmt (i
), 0, dump_flags
);
1260 fprintf (dump_file
, "\n");
1265 fini_object_sizes ();
1269 struct gimple_opt_pass pass_object_sizes
=
1275 compute_object_sizes
, /* execute */
1278 0, /* static_pass_number */
1279 TV_NONE
, /* tv_id */
1280 PROP_cfg
| PROP_ssa
, /* properties_required */
1281 0, /* properties_provided */
1282 0, /* properties_destroyed */
1283 0, /* todo_flags_start */
1284 TODO_verify_ssa
/* todo_flags_finish */