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0a39fd54 | 1 | /* __builtin_object_size (ptr, object_size_type) computation |
2 | Copyright (C) 2004, 2005 Free Software Foundation, Inc. | |
3 | Contributed by Jakub Jelinek <jakub@redhat.com> | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
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 2, or (at your option) | |
10 | any later version. | |
11 | ||
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. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to | |
c2b61805 | 19 | the Free Software Foundation, 51 Franklin Street, Fifth Floor, |
20 | Boston, MA 02110-1301, USA. */ | |
0a39fd54 | 21 | |
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "tree.h" | |
27 | #include "diagnostic.h" | |
28 | #include "tree-flow.h" | |
29 | #include "tree-pass.h" | |
30 | #include "tree-ssa-propagate.h" | |
31 | ||
32 | struct object_size_info | |
33 | { | |
34 | int object_size_type; | |
35 | bitmap visited, reexamine; | |
36 | int pass; | |
37 | bool changed; | |
38 | unsigned int *depths; | |
39 | unsigned int *stack, *tos; | |
40 | }; | |
41 | ||
42 | static unsigned HOST_WIDE_INT unknown[4] = { -1, -1, 0, 0 }; | |
43 | ||
44 | static tree compute_object_offset (tree, tree); | |
45 | static unsigned HOST_WIDE_INT addr_object_size (tree, int); | |
46 | static unsigned HOST_WIDE_INT alloc_object_size (tree, int); | |
47 | static tree pass_through_call (tree); | |
48 | static void collect_object_sizes_for (struct object_size_info *, tree); | |
49 | static void expr_object_size (struct object_size_info *, tree, tree); | |
50 | static bool merge_object_sizes (struct object_size_info *, tree, tree, | |
51 | unsigned HOST_WIDE_INT); | |
52 | static bool plus_expr_object_size (struct object_size_info *, tree, tree); | |
2a1990e9 | 53 | static unsigned int compute_object_sizes (void); |
0a39fd54 | 54 | static void init_offset_limit (void); |
55 | static void check_for_plus_in_loops (struct object_size_info *, tree); | |
56 | static void check_for_plus_in_loops_1 (struct object_size_info *, tree, | |
57 | unsigned int); | |
58 | ||
59 | /* object_sizes[0] is upper bound for number of bytes till the end of | |
60 | the object. | |
61 | object_sizes[1] is upper bound for number of bytes till the end of | |
62 | the subobject (innermost array or field with address taken). | |
63 | object_sizes[2] is lower bound for number of bytes till the end of | |
64 | the object and object_sizes[3] lower bound for subobject. */ | |
65 | static unsigned HOST_WIDE_INT *object_sizes[4]; | |
66 | ||
67 | /* Bitmaps what object sizes have been computed already. */ | |
68 | static bitmap computed[4]; | |
69 | ||
70 | /* Maximum value of offset we consider to be addition. */ | |
71 | static unsigned HOST_WIDE_INT offset_limit; | |
72 | ||
73 | ||
74 | /* Initialize OFFSET_LIMIT variable. */ | |
75 | static void | |
76 | init_offset_limit (void) | |
77 | { | |
78 | if (host_integerp (TYPE_MAX_VALUE (sizetype), 1)) | |
79 | offset_limit = tree_low_cst (TYPE_MAX_VALUE (sizetype), 1); | |
80 | else | |
81 | offset_limit = -1; | |
82 | offset_limit /= 2; | |
83 | } | |
84 | ||
85 | ||
86 | /* Compute offset of EXPR within VAR. Return error_mark_node | |
87 | if unknown. */ | |
88 | ||
89 | static tree | |
90 | compute_object_offset (tree expr, tree var) | |
91 | { | |
92 | enum tree_code code = PLUS_EXPR; | |
93 | tree base, off, t; | |
94 | ||
95 | if (expr == var) | |
96 | return size_zero_node; | |
97 | ||
98 | switch (TREE_CODE (expr)) | |
99 | { | |
100 | case COMPONENT_REF: | |
101 | base = compute_object_offset (TREE_OPERAND (expr, 0), var); | |
102 | if (base == error_mark_node) | |
103 | return base; | |
104 | ||
105 | t = TREE_OPERAND (expr, 1); | |
106 | off = size_binop (PLUS_EXPR, DECL_FIELD_OFFSET (t), | |
107 | size_int (tree_low_cst (DECL_FIELD_BIT_OFFSET (t), 1) | |
108 | / BITS_PER_UNIT)); | |
109 | break; | |
110 | ||
111 | case REALPART_EXPR: | |
112 | case NOP_EXPR: | |
113 | case CONVERT_EXPR: | |
114 | case VIEW_CONVERT_EXPR: | |
115 | case NON_LVALUE_EXPR: | |
116 | return compute_object_offset (TREE_OPERAND (expr, 0), var); | |
117 | ||
118 | case IMAGPART_EXPR: | |
119 | base = compute_object_offset (TREE_OPERAND (expr, 0), var); | |
120 | if (base == error_mark_node) | |
121 | return base; | |
122 | ||
123 | off = TYPE_SIZE_UNIT (TREE_TYPE (expr)); | |
124 | break; | |
125 | ||
126 | case ARRAY_REF: | |
127 | base = compute_object_offset (TREE_OPERAND (expr, 0), var); | |
128 | if (base == error_mark_node) | |
129 | return base; | |
130 | ||
131 | t = TREE_OPERAND (expr, 1); | |
132 | if (TREE_CODE (t) == INTEGER_CST && tree_int_cst_sgn (t) < 0) | |
133 | { | |
134 | code = MINUS_EXPR; | |
135 | t = fold_build1 (NEGATE_EXPR, TREE_TYPE (t), t); | |
136 | } | |
137 | t = convert (sizetype, t); | |
138 | off = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (TREE_TYPE (expr)), t); | |
139 | break; | |
140 | ||
141 | default: | |
142 | return error_mark_node; | |
143 | } | |
144 | ||
145 | return size_binop (code, base, off); | |
146 | } | |
147 | ||
148 | ||
149 | /* Compute __builtin_object_size for PTR, which is a ADDR_EXPR. | |
150 | OBJECT_SIZE_TYPE is the second argument from __builtin_object_size. | |
151 | If unknown, return unknown[object_size_type]. */ | |
152 | ||
153 | static unsigned HOST_WIDE_INT | |
154 | addr_object_size (tree ptr, int object_size_type) | |
155 | { | |
156 | tree pt_var; | |
157 | ||
158 | gcc_assert (TREE_CODE (ptr) == ADDR_EXPR); | |
159 | ||
160 | pt_var = TREE_OPERAND (ptr, 0); | |
161 | if (REFERENCE_CLASS_P (pt_var)) | |
162 | pt_var = get_base_address (pt_var); | |
163 | ||
164 | if (pt_var | |
165 | && (SSA_VAR_P (pt_var) || TREE_CODE (pt_var) == STRING_CST) | |
166 | && TYPE_SIZE_UNIT (TREE_TYPE (pt_var)) | |
167 | && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), 1) | |
168 | && (unsigned HOST_WIDE_INT) | |
169 | tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), 1) < offset_limit) | |
170 | { | |
171 | tree bytes; | |
172 | ||
173 | if (pt_var != TREE_OPERAND (ptr, 0)) | |
174 | { | |
175 | tree var; | |
176 | ||
177 | if (object_size_type & 1) | |
178 | { | |
179 | var = TREE_OPERAND (ptr, 0); | |
180 | ||
181 | while (var != pt_var | |
182 | && TREE_CODE (var) != BIT_FIELD_REF | |
183 | && TREE_CODE (var) != COMPONENT_REF | |
184 | && TREE_CODE (var) != ARRAY_REF | |
185 | && TREE_CODE (var) != ARRAY_RANGE_REF | |
186 | && TREE_CODE (var) != REALPART_EXPR | |
187 | && TREE_CODE (var) != IMAGPART_EXPR) | |
188 | var = TREE_OPERAND (var, 0); | |
189 | if (var != pt_var && TREE_CODE (var) == ARRAY_REF) | |
190 | var = TREE_OPERAND (var, 0); | |
191 | if (! TYPE_SIZE_UNIT (TREE_TYPE (var)) | |
192 | || ! host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (var)), 1) | |
193 | || tree_int_cst_lt (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), | |
194 | TYPE_SIZE_UNIT (TREE_TYPE (var)))) | |
195 | var = pt_var; | |
196 | } | |
197 | else | |
198 | var = pt_var; | |
199 | ||
200 | bytes = compute_object_offset (TREE_OPERAND (ptr, 0), var); | |
201 | if (bytes != error_mark_node) | |
202 | { | |
203 | if (TREE_CODE (bytes) == INTEGER_CST | |
204 | && tree_int_cst_lt (TYPE_SIZE_UNIT (TREE_TYPE (var)), bytes)) | |
205 | bytes = size_zero_node; | |
206 | else | |
207 | bytes = size_binop (MINUS_EXPR, | |
208 | TYPE_SIZE_UNIT (TREE_TYPE (var)), bytes); | |
209 | } | |
210 | } | |
211 | else | |
212 | bytes = TYPE_SIZE_UNIT (TREE_TYPE (pt_var)); | |
213 | ||
214 | if (host_integerp (bytes, 1)) | |
215 | return tree_low_cst (bytes, 1); | |
216 | } | |
217 | ||
218 | return unknown[object_size_type]; | |
219 | } | |
220 | ||
221 | ||
222 | /* Compute __builtin_object_size for CALL, which is a CALL_EXPR. | |
223 | Handles various allocation calls. OBJECT_SIZE_TYPE is the second | |
224 | argument from __builtin_object_size. If unknown, return | |
225 | unknown[object_size_type]. */ | |
226 | ||
227 | static unsigned HOST_WIDE_INT | |
228 | alloc_object_size (tree call, int object_size_type) | |
229 | { | |
230 | tree callee, arglist, a, bytes = NULL_TREE; | |
231 | unsigned int arg_mask = 0; | |
232 | ||
233 | gcc_assert (TREE_CODE (call) == CALL_EXPR); | |
234 | ||
235 | callee = get_callee_fndecl (call); | |
236 | arglist = TREE_OPERAND (call, 1); | |
237 | if (callee | |
238 | && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) | |
239 | switch (DECL_FUNCTION_CODE (callee)) | |
240 | { | |
241 | case BUILT_IN_MALLOC: | |
242 | case BUILT_IN_ALLOCA: | |
243 | arg_mask = 1; | |
244 | break; | |
245 | /* | |
246 | case BUILT_IN_REALLOC: | |
247 | arg_mask = 2; | |
248 | break; | |
249 | */ | |
250 | case BUILT_IN_CALLOC: | |
251 | arg_mask = 3; | |
252 | break; | |
253 | default: | |
254 | break; | |
255 | } | |
256 | ||
257 | for (a = arglist; arg_mask && a; arg_mask >>= 1, a = TREE_CHAIN (a)) | |
258 | if (arg_mask & 1) | |
259 | { | |
260 | tree arg = TREE_VALUE (a); | |
261 | ||
262 | if (TREE_CODE (arg) != INTEGER_CST) | |
263 | break; | |
264 | ||
265 | if (! bytes) | |
266 | bytes = fold_convert (sizetype, arg); | |
267 | else | |
268 | bytes = size_binop (MULT_EXPR, bytes, | |
269 | fold_convert (sizetype, arg)); | |
270 | } | |
271 | ||
272 | if (! arg_mask && bytes && host_integerp (bytes, 1)) | |
273 | return tree_low_cst (bytes, 1); | |
274 | ||
275 | return unknown[object_size_type]; | |
276 | } | |
277 | ||
278 | ||
279 | /* If object size is propagated from one of function's arguments directly | |
280 | to its return value, return that argument for CALL_EXPR CALL. | |
281 | Otherwise return NULL. */ | |
282 | ||
283 | static tree | |
284 | pass_through_call (tree call) | |
285 | { | |
286 | tree callee = get_callee_fndecl (call); | |
287 | tree arglist = TREE_OPERAND (call, 1); | |
288 | ||
289 | if (callee | |
290 | && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) | |
291 | switch (DECL_FUNCTION_CODE (callee)) | |
292 | { | |
293 | case BUILT_IN_MEMCPY: | |
294 | case BUILT_IN_MEMMOVE: | |
295 | case BUILT_IN_MEMSET: | |
296 | case BUILT_IN_STRCPY: | |
297 | case BUILT_IN_STRNCPY: | |
298 | case BUILT_IN_STRCAT: | |
299 | case BUILT_IN_STRNCAT: | |
300 | case BUILT_IN_MEMCPY_CHK: | |
301 | case BUILT_IN_MEMMOVE_CHK: | |
302 | case BUILT_IN_MEMSET_CHK: | |
303 | case BUILT_IN_STRCPY_CHK: | |
304 | case BUILT_IN_STRNCPY_CHK: | |
305 | case BUILT_IN_STRCAT_CHK: | |
306 | case BUILT_IN_STRNCAT_CHK: | |
307 | if (arglist) | |
308 | return TREE_VALUE (arglist); | |
309 | break; | |
310 | default: | |
311 | break; | |
312 | } | |
313 | ||
314 | return NULL_TREE; | |
315 | } | |
316 | ||
317 | ||
318 | /* Compute __builtin_object_size value for PTR. OBJECT_SIZE_TYPE is the | |
319 | second argument from __builtin_object_size. */ | |
320 | ||
321 | unsigned HOST_WIDE_INT | |
322 | compute_builtin_object_size (tree ptr, int object_size_type) | |
323 | { | |
324 | gcc_assert (object_size_type >= 0 && object_size_type <= 3); | |
325 | ||
326 | if (! offset_limit) | |
327 | init_offset_limit (); | |
328 | ||
329 | if (TREE_CODE (ptr) == ADDR_EXPR) | |
330 | return addr_object_size (ptr, object_size_type); | |
331 | else if (TREE_CODE (ptr) == CALL_EXPR) | |
332 | { | |
333 | tree arg = pass_through_call (ptr); | |
334 | ||
335 | if (arg) | |
336 | return compute_builtin_object_size (arg, object_size_type); | |
337 | else | |
338 | return alloc_object_size (ptr, object_size_type); | |
339 | } | |
340 | else if (TREE_CODE (ptr) == SSA_NAME | |
341 | && POINTER_TYPE_P (TREE_TYPE (ptr)) | |
342 | && object_sizes[object_size_type] != NULL) | |
343 | { | |
344 | if (!bitmap_bit_p (computed[object_size_type], SSA_NAME_VERSION (ptr))) | |
345 | { | |
346 | struct object_size_info osi; | |
347 | bitmap_iterator bi; | |
348 | unsigned int i; | |
349 | ||
350 | if (dump_file) | |
351 | { | |
352 | fprintf (dump_file, "Computing %s %sobject size for ", | |
353 | (object_size_type & 2) ? "minimum" : "maximum", | |
354 | (object_size_type & 1) ? "sub" : ""); | |
355 | print_generic_expr (dump_file, ptr, dump_flags); | |
356 | fprintf (dump_file, ":\n"); | |
357 | } | |
358 | ||
359 | osi.visited = BITMAP_ALLOC (NULL); | |
360 | osi.reexamine = BITMAP_ALLOC (NULL); | |
361 | osi.object_size_type = object_size_type; | |
362 | osi.depths = NULL; | |
363 | osi.stack = NULL; | |
364 | osi.tos = NULL; | |
365 | ||
366 | /* First pass: walk UD chains, compute object sizes that | |
367 | can be computed. osi.reexamine bitmap at the end will | |
368 | contain what variables were found in dependency cycles | |
369 | and therefore need to be reexamined. */ | |
370 | osi.pass = 0; | |
371 | osi.changed = false; | |
372 | collect_object_sizes_for (&osi, ptr); | |
373 | ||
374 | /* Second pass: keep recomputing object sizes of variables | |
375 | that need reexamination, until no object sizes are | |
376 | increased or all object sizes are computed. */ | |
377 | if (! bitmap_empty_p (osi.reexamine)) | |
378 | { | |
379 | bitmap reexamine = BITMAP_ALLOC (NULL); | |
380 | ||
381 | /* If looking for minimum instead of maximum object size, | |
382 | detect cases where a pointer is increased in a loop. | |
383 | Although even without this detection pass 2 would eventually | |
384 | terminate, it could take a long time. If a pointer is | |
385 | increasing this way, we need to assume 0 object size. | |
386 | E.g. p = &buf[0]; while (cond) p = p + 4; */ | |
387 | if (object_size_type & 2) | |
388 | { | |
4c36ffe6 | 389 | osi.depths = XCNEWVEC (unsigned int, num_ssa_names); |
390 | osi.stack = XNEWVEC (unsigned int, num_ssa_names); | |
0a39fd54 | 391 | osi.tos = osi.stack; |
392 | osi.pass = 1; | |
393 | /* collect_object_sizes_for is changing | |
394 | osi.reexamine bitmap, so iterate over a copy. */ | |
395 | bitmap_copy (reexamine, osi.reexamine); | |
396 | EXECUTE_IF_SET_IN_BITMAP (reexamine, 0, i, bi) | |
397 | if (bitmap_bit_p (osi.reexamine, i)) | |
398 | check_for_plus_in_loops (&osi, ssa_name (i)); | |
399 | ||
400 | free (osi.depths); | |
401 | osi.depths = NULL; | |
402 | free (osi.stack); | |
403 | osi.stack = NULL; | |
404 | osi.tos = NULL; | |
405 | } | |
406 | ||
407 | do | |
408 | { | |
409 | osi.pass = 2; | |
410 | osi.changed = false; | |
411 | /* collect_object_sizes_for is changing | |
412 | osi.reexamine bitmap, so iterate over a copy. */ | |
413 | bitmap_copy (reexamine, osi.reexamine); | |
414 | EXECUTE_IF_SET_IN_BITMAP (reexamine, 0, i, bi) | |
415 | if (bitmap_bit_p (osi.reexamine, i)) | |
416 | { | |
417 | collect_object_sizes_for (&osi, ssa_name (i)); | |
418 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
419 | { | |
420 | fprintf (dump_file, "Reexamining "); | |
421 | print_generic_expr (dump_file, ssa_name (i), | |
422 | dump_flags); | |
423 | fprintf (dump_file, "\n"); | |
424 | } | |
425 | } | |
426 | } | |
427 | while (osi.changed); | |
428 | ||
429 | BITMAP_FREE (reexamine); | |
430 | } | |
431 | EXECUTE_IF_SET_IN_BITMAP (osi.reexamine, 0, i, bi) | |
432 | bitmap_set_bit (computed[object_size_type], i); | |
433 | ||
434 | /* Debugging dumps. */ | |
435 | if (dump_file) | |
436 | { | |
437 | EXECUTE_IF_SET_IN_BITMAP (osi.visited, 0, i, bi) | |
438 | if (object_sizes[object_size_type][i] | |
439 | != unknown[object_size_type]) | |
440 | { | |
441 | print_generic_expr (dump_file, ssa_name (i), | |
442 | dump_flags); | |
443 | fprintf (dump_file, | |
444 | ": %s %sobject size " | |
445 | HOST_WIDE_INT_PRINT_UNSIGNED "\n", | |
446 | (object_size_type & 2) ? "minimum" : "maximum", | |
447 | (object_size_type & 1) ? "sub" : "", | |
448 | object_sizes[object_size_type][i]); | |
449 | } | |
450 | } | |
451 | ||
452 | BITMAP_FREE (osi.reexamine); | |
453 | BITMAP_FREE (osi.visited); | |
454 | } | |
455 | ||
456 | return object_sizes[object_size_type][SSA_NAME_VERSION (ptr)]; | |
457 | } | |
458 | ||
459 | return unknown[object_size_type]; | |
460 | } | |
461 | ||
462 | ||
463 | /* Compute object_sizes for PTR, defined to VALUE, which is not | |
464 | a SSA_NAME. */ | |
465 | ||
466 | static void | |
467 | expr_object_size (struct object_size_info *osi, tree ptr, tree value) | |
468 | { | |
469 | int object_size_type = osi->object_size_type; | |
470 | unsigned int varno = SSA_NAME_VERSION (ptr); | |
471 | unsigned HOST_WIDE_INT bytes; | |
472 | ||
473 | gcc_assert (object_sizes[object_size_type][varno] | |
474 | != unknown[object_size_type]); | |
475 | gcc_assert (osi->pass == 0); | |
476 | ||
477 | if (TREE_CODE (value) == WITH_SIZE_EXPR) | |
478 | value = TREE_OPERAND (value, 0); | |
479 | ||
480 | /* Pointer variables should have been handled by merge_object_sizes. */ | |
481 | gcc_assert (TREE_CODE (value) != SSA_NAME | |
482 | || !POINTER_TYPE_P (TREE_TYPE (value))); | |
483 | ||
484 | if (TREE_CODE (value) == ADDR_EXPR) | |
485 | bytes = addr_object_size (value, object_size_type); | |
486 | else if (TREE_CODE (value) == CALL_EXPR) | |
487 | bytes = alloc_object_size (value, object_size_type); | |
488 | else | |
489 | bytes = unknown[object_size_type]; | |
490 | ||
491 | if ((object_size_type & 2) == 0) | |
492 | { | |
493 | if (object_sizes[object_size_type][varno] < bytes) | |
494 | object_sizes[object_size_type][varno] = bytes; | |
495 | } | |
496 | else | |
497 | { | |
498 | if (object_sizes[object_size_type][varno] > bytes) | |
499 | object_sizes[object_size_type][varno] = bytes; | |
500 | } | |
501 | } | |
502 | ||
503 | ||
504 | /* Merge object sizes of ORIG + OFFSET into DEST. Return true if | |
505 | the object size might need reexamination later. */ | |
506 | ||
507 | static bool | |
508 | merge_object_sizes (struct object_size_info *osi, tree dest, tree orig, | |
509 | unsigned HOST_WIDE_INT offset) | |
510 | { | |
511 | int object_size_type = osi->object_size_type; | |
512 | unsigned int varno = SSA_NAME_VERSION (dest); | |
513 | unsigned HOST_WIDE_INT orig_bytes; | |
514 | ||
515 | if (object_sizes[object_size_type][varno] == unknown[object_size_type]) | |
516 | return false; | |
517 | if (offset >= offset_limit) | |
518 | { | |
519 | object_sizes[object_size_type][varno] = unknown[object_size_type]; | |
520 | return false; | |
521 | } | |
522 | ||
523 | if (osi->pass == 0) | |
524 | collect_object_sizes_for (osi, orig); | |
525 | ||
526 | orig_bytes = object_sizes[object_size_type][SSA_NAME_VERSION (orig)]; | |
527 | if (orig_bytes != unknown[object_size_type]) | |
528 | orig_bytes = (offset > orig_bytes) | |
529 | ? (unsigned HOST_WIDE_INT) 0 : orig_bytes - offset; | |
530 | ||
531 | if ((object_size_type & 2) == 0) | |
532 | { | |
533 | if (object_sizes[object_size_type][varno] < orig_bytes) | |
534 | { | |
535 | object_sizes[object_size_type][varno] = orig_bytes; | |
536 | osi->changed = true; | |
537 | } | |
538 | } | |
539 | else | |
540 | { | |
541 | if (object_sizes[object_size_type][varno] > orig_bytes) | |
542 | { | |
543 | object_sizes[object_size_type][varno] = orig_bytes; | |
544 | osi->changed = true; | |
545 | } | |
546 | } | |
547 | return bitmap_bit_p (osi->reexamine, SSA_NAME_VERSION (orig)); | |
548 | } | |
549 | ||
550 | ||
551 | /* Compute object_sizes for PTR, defined to VALUE, which is | |
552 | a PLUS_EXPR. Return true if the object size might need reexamination | |
553 | later. */ | |
554 | ||
555 | static bool | |
556 | plus_expr_object_size (struct object_size_info *osi, tree var, tree value) | |
557 | { | |
558 | tree op0 = TREE_OPERAND (value, 0); | |
559 | tree op1 = TREE_OPERAND (value, 1); | |
560 | bool ptr1_p = POINTER_TYPE_P (TREE_TYPE (op0)) | |
561 | && TREE_CODE (op0) != INTEGER_CST; | |
562 | bool ptr2_p = POINTER_TYPE_P (TREE_TYPE (op1)) | |
563 | && TREE_CODE (op1) != INTEGER_CST; | |
564 | int object_size_type = osi->object_size_type; | |
565 | unsigned int varno = SSA_NAME_VERSION (var); | |
566 | unsigned HOST_WIDE_INT bytes; | |
567 | ||
568 | gcc_assert (TREE_CODE (value) == PLUS_EXPR); | |
569 | ||
570 | if (object_sizes[object_size_type][varno] == unknown[object_size_type]) | |
571 | return false; | |
572 | ||
573 | /* Swap operands if needed. */ | |
574 | if (ptr2_p && !ptr1_p) | |
575 | { | |
576 | tree tem = op0; | |
577 | op0 = op1; | |
578 | op1 = tem; | |
579 | ptr1_p = true; | |
580 | ptr2_p = false; | |
581 | } | |
582 | ||
583 | /* Handle PTR + OFFSET here. */ | |
584 | if (ptr1_p | |
585 | && !ptr2_p | |
586 | && TREE_CODE (op1) == INTEGER_CST | |
587 | && (TREE_CODE (op0) == SSA_NAME | |
588 | || TREE_CODE (op0) == ADDR_EXPR)) | |
589 | { | |
590 | if (! host_integerp (op1, 1)) | |
591 | bytes = unknown[object_size_type]; | |
592 | else if (TREE_CODE (op0) == SSA_NAME) | |
593 | return merge_object_sizes (osi, var, op0, tree_low_cst (op1, 1)); | |
594 | else | |
595 | { | |
596 | unsigned HOST_WIDE_INT off = tree_low_cst (op1, 1); | |
597 | ||
598 | bytes = compute_builtin_object_size (value, object_size_type); | |
599 | if (off > offset_limit) | |
600 | bytes = unknown[object_size_type]; | |
601 | else if (off > bytes) | |
602 | bytes = 0; | |
603 | else | |
604 | bytes -= off; | |
605 | } | |
606 | } | |
607 | else | |
608 | bytes = unknown[object_size_type]; | |
609 | ||
610 | if ((object_size_type & 2) == 0) | |
611 | { | |
612 | if (object_sizes[object_size_type][varno] < bytes) | |
613 | object_sizes[object_size_type][varno] = bytes; | |
614 | } | |
615 | else | |
616 | { | |
617 | if (object_sizes[object_size_type][varno] > bytes) | |
618 | object_sizes[object_size_type][varno] = bytes; | |
619 | } | |
620 | return false; | |
621 | } | |
622 | ||
623 | ||
624 | /* Compute object sizes for VAR. | |
625 | For ADDR_EXPR an object size is the number of remaining bytes | |
56d36a49 | 626 | to the end of the object (where what is considered an object depends on |
0a39fd54 | 627 | OSI->object_size_type). |
628 | For allocation CALL_EXPR like malloc or calloc object size is the size | |
629 | of the allocation. | |
630 | For pointer PLUS_EXPR where second operand is a constant integer, | |
631 | object size is object size of the first operand minus the constant. | |
632 | If the constant is bigger than the number of remaining bytes until the | |
633 | end of the object, object size is 0, but if it is instead a pointer | |
634 | subtraction, object size is unknown[object_size_type]. | |
635 | To differentiate addition from subtraction, ADDR_EXPR returns | |
636 | unknown[object_size_type] for all objects bigger than half of the address | |
637 | space, and constants less than half of the address space are considered | |
638 | addition, while bigger constants subtraction. | |
639 | For a memcpy like CALL_EXPR that always returns one of its arguments, the | |
640 | object size is object size of that argument. | |
641 | Otherwise, object size is the maximum of object sizes of variables | |
642 | that it might be set to. */ | |
643 | ||
644 | static void | |
645 | collect_object_sizes_for (struct object_size_info *osi, tree var) | |
646 | { | |
647 | int object_size_type = osi->object_size_type; | |
648 | unsigned int varno = SSA_NAME_VERSION (var); | |
649 | tree stmt; | |
650 | bool reexamine; | |
651 | ||
652 | if (bitmap_bit_p (computed[object_size_type], varno)) | |
653 | return; | |
654 | ||
655 | if (osi->pass == 0) | |
656 | { | |
657 | if (! bitmap_bit_p (osi->visited, varno)) | |
658 | { | |
659 | bitmap_set_bit (osi->visited, varno); | |
660 | object_sizes[object_size_type][varno] | |
661 | = (object_size_type & 2) ? -1 : 0; | |
662 | } | |
663 | else | |
664 | { | |
665 | /* Found a dependency loop. Mark the variable for later | |
666 | re-examination. */ | |
667 | bitmap_set_bit (osi->reexamine, varno); | |
668 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
669 | { | |
670 | fprintf (dump_file, "Found a dependency loop at "); | |
671 | print_generic_expr (dump_file, var, dump_flags); | |
672 | fprintf (dump_file, "\n"); | |
673 | } | |
674 | return; | |
675 | } | |
676 | } | |
677 | ||
678 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
679 | { | |
680 | fprintf (dump_file, "Visiting use-def links for "); | |
681 | print_generic_expr (dump_file, var, dump_flags); | |
682 | fprintf (dump_file, "\n"); | |
683 | } | |
684 | ||
685 | stmt = SSA_NAME_DEF_STMT (var); | |
686 | reexamine = false; | |
687 | ||
688 | switch (TREE_CODE (stmt)) | |
689 | { | |
690 | case RETURN_EXPR: | |
6276113b | 691 | gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); |
0a39fd54 | 692 | stmt = TREE_OPERAND (stmt, 0); |
693 | /* FALLTHRU */ | |
694 | ||
695 | case MODIFY_EXPR: | |
696 | { | |
697 | tree rhs = TREE_OPERAND (stmt, 1), arg; | |
698 | STRIP_NOPS (rhs); | |
699 | ||
700 | if (TREE_CODE (rhs) == CALL_EXPR) | |
701 | { | |
702 | arg = pass_through_call (rhs); | |
703 | if (arg) | |
704 | rhs = arg; | |
705 | } | |
706 | ||
707 | if (TREE_CODE (rhs) == SSA_NAME | |
708 | && POINTER_TYPE_P (TREE_TYPE (rhs))) | |
709 | reexamine = merge_object_sizes (osi, var, rhs, 0); | |
710 | ||
711 | else if (TREE_CODE (rhs) == PLUS_EXPR) | |
712 | reexamine = plus_expr_object_size (osi, var, rhs); | |
713 | ||
714 | else | |
715 | expr_object_size (osi, var, rhs); | |
716 | break; | |
717 | } | |
718 | ||
719 | case ASM_EXPR: | |
720 | /* Pointers defined by __asm__ statements can point anywhere. */ | |
721 | object_sizes[object_size_type][varno] = unknown[object_size_type]; | |
722 | break; | |
723 | ||
724 | case NOP_EXPR: | |
725 | { | |
726 | tree decl = SSA_NAME_VAR (var); | |
727 | ||
728 | gcc_assert (IS_EMPTY_STMT (stmt)); | |
729 | ||
730 | if (TREE_CODE (decl) != PARM_DECL && DECL_INITIAL (decl)) | |
731 | expr_object_size (osi, var, DECL_INITIAL (decl)); | |
732 | else | |
733 | expr_object_size (osi, var, decl); | |
734 | } | |
735 | break; | |
736 | ||
737 | case PHI_NODE: | |
738 | { | |
739 | int i; | |
740 | ||
741 | for (i = 0; i < PHI_NUM_ARGS (stmt); i++) | |
742 | { | |
743 | tree rhs = PHI_ARG_DEF (stmt, i); | |
744 | ||
745 | if (object_sizes[object_size_type][varno] | |
746 | == unknown[object_size_type]) | |
747 | break; | |
748 | ||
749 | if (TREE_CODE (rhs) == SSA_NAME) | |
750 | reexamine |= merge_object_sizes (osi, var, rhs, 0); | |
751 | else if (osi->pass == 0) | |
752 | expr_object_size (osi, var, rhs); | |
753 | } | |
754 | break; | |
755 | } | |
756 | default: | |
757 | gcc_unreachable (); | |
758 | } | |
759 | ||
760 | if (! reexamine | |
761 | || object_sizes[object_size_type][varno] == unknown[object_size_type]) | |
762 | { | |
763 | bitmap_set_bit (computed[object_size_type], varno); | |
764 | bitmap_clear_bit (osi->reexamine, varno); | |
765 | } | |
766 | else | |
767 | { | |
768 | bitmap_set_bit (osi->reexamine, varno); | |
769 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
770 | { | |
771 | fprintf (dump_file, "Need to reexamine "); | |
772 | print_generic_expr (dump_file, var, dump_flags); | |
773 | fprintf (dump_file, "\n"); | |
774 | } | |
775 | } | |
776 | } | |
777 | ||
778 | ||
779 | /* Helper function for check_for_plus_in_loops. Called recursively | |
780 | to detect loops. */ | |
781 | ||
782 | static void | |
783 | check_for_plus_in_loops_1 (struct object_size_info *osi, tree var, | |
784 | unsigned int depth) | |
785 | { | |
786 | tree stmt = SSA_NAME_DEF_STMT (var); | |
787 | unsigned int varno = SSA_NAME_VERSION (var); | |
788 | ||
789 | if (osi->depths[varno]) | |
790 | { | |
791 | if (osi->depths[varno] != depth) | |
792 | { | |
793 | unsigned int *sp; | |
794 | ||
795 | /* Found a loop involving pointer addition. */ | |
796 | for (sp = osi->tos; sp > osi->stack; ) | |
797 | { | |
798 | --sp; | |
799 | bitmap_clear_bit (osi->reexamine, *sp); | |
800 | bitmap_set_bit (computed[osi->object_size_type], *sp); | |
801 | object_sizes[osi->object_size_type][*sp] = 0; | |
802 | if (*sp == varno) | |
803 | break; | |
804 | } | |
805 | } | |
806 | return; | |
807 | } | |
808 | else if (! bitmap_bit_p (osi->reexamine, varno)) | |
809 | return; | |
810 | ||
811 | osi->depths[varno] = depth; | |
812 | *osi->tos++ = varno; | |
813 | ||
814 | switch (TREE_CODE (stmt)) | |
815 | { | |
816 | case RETURN_EXPR: | |
6276113b | 817 | gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); |
0a39fd54 | 818 | stmt = TREE_OPERAND (stmt, 0); |
819 | /* FALLTHRU */ | |
820 | ||
821 | case MODIFY_EXPR: | |
822 | { | |
823 | tree rhs = TREE_OPERAND (stmt, 1), arg; | |
824 | STRIP_NOPS (rhs); | |
825 | ||
826 | if (TREE_CODE (rhs) == CALL_EXPR) | |
827 | { | |
828 | arg = pass_through_call (rhs); | |
829 | if (arg) | |
830 | rhs = arg; | |
831 | } | |
832 | ||
833 | if (TREE_CODE (rhs) == SSA_NAME) | |
834 | check_for_plus_in_loops_1 (osi, rhs, depth); | |
835 | else if (TREE_CODE (rhs) == PLUS_EXPR) | |
836 | { | |
837 | tree op0 = TREE_OPERAND (rhs, 0); | |
838 | tree op1 = TREE_OPERAND (rhs, 1); | |
839 | tree cst, basevar; | |
840 | ||
841 | if (TREE_CODE (op0) == SSA_NAME) | |
842 | { | |
843 | basevar = op0; | |
844 | cst = op1; | |
845 | } | |
846 | else | |
847 | { | |
848 | basevar = op1; | |
849 | cst = op0; | |
850 | gcc_assert (TREE_CODE (basevar) == SSA_NAME); | |
851 | } | |
852 | gcc_assert (TREE_CODE (cst) == INTEGER_CST); | |
853 | ||
854 | check_for_plus_in_loops_1 (osi, basevar, | |
855 | depth + !integer_zerop (cst)); | |
856 | } | |
857 | else | |
858 | gcc_unreachable (); | |
859 | break; | |
860 | } | |
861 | case PHI_NODE: | |
862 | { | |
863 | int i; | |
864 | ||
865 | for (i = 0; i < PHI_NUM_ARGS (stmt); i++) | |
866 | { | |
867 | tree rhs = PHI_ARG_DEF (stmt, i); | |
868 | ||
869 | if (TREE_CODE (rhs) == SSA_NAME) | |
870 | check_for_plus_in_loops_1 (osi, rhs, depth); | |
871 | } | |
872 | break; | |
873 | } | |
874 | default: | |
875 | gcc_unreachable (); | |
876 | } | |
877 | ||
878 | osi->depths[varno] = 0; | |
879 | osi->tos--; | |
880 | } | |
881 | ||
882 | ||
883 | /* Check if some pointer we are computing object size of is being increased | |
884 | within a loop. If yes, assume all the SSA variables participating in | |
885 | that loop have minimum object sizes 0. */ | |
886 | ||
887 | static void | |
888 | check_for_plus_in_loops (struct object_size_info *osi, tree var) | |
889 | { | |
890 | tree stmt = SSA_NAME_DEF_STMT (var); | |
891 | ||
892 | switch (TREE_CODE (stmt)) | |
893 | { | |
894 | case RETURN_EXPR: | |
6276113b | 895 | gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); |
0a39fd54 | 896 | stmt = TREE_OPERAND (stmt, 0); |
897 | /* FALLTHRU */ | |
898 | ||
899 | case MODIFY_EXPR: | |
900 | { | |
901 | tree rhs = TREE_OPERAND (stmt, 1), arg; | |
902 | STRIP_NOPS (rhs); | |
903 | ||
904 | if (TREE_CODE (rhs) == CALL_EXPR) | |
905 | { | |
906 | arg = pass_through_call (rhs); | |
907 | if (arg) | |
908 | rhs = arg; | |
909 | } | |
910 | ||
911 | if (TREE_CODE (rhs) == PLUS_EXPR) | |
912 | { | |
913 | tree op0 = TREE_OPERAND (rhs, 0); | |
914 | tree op1 = TREE_OPERAND (rhs, 1); | |
915 | tree cst, basevar; | |
916 | ||
917 | if (TREE_CODE (op0) == SSA_NAME) | |
918 | { | |
919 | basevar = op0; | |
920 | cst = op1; | |
921 | } | |
922 | else | |
923 | { | |
924 | basevar = op1; | |
925 | cst = op0; | |
926 | gcc_assert (TREE_CODE (basevar) == SSA_NAME); | |
927 | } | |
928 | gcc_assert (TREE_CODE (cst) == INTEGER_CST); | |
929 | ||
930 | if (integer_zerop (cst)) | |
931 | break; | |
932 | ||
933 | osi->depths[SSA_NAME_VERSION (basevar)] = 1; | |
934 | *osi->tos++ = SSA_NAME_VERSION (basevar); | |
935 | check_for_plus_in_loops_1 (osi, var, 2); | |
936 | osi->depths[SSA_NAME_VERSION (basevar)] = 0; | |
937 | osi->tos--; | |
938 | } | |
939 | break; | |
940 | } | |
941 | default: | |
942 | break; | |
943 | } | |
944 | } | |
945 | ||
946 | ||
947 | /* Initialize data structures for the object size computation. */ | |
948 | ||
949 | void | |
950 | init_object_sizes (void) | |
951 | { | |
952 | int object_size_type; | |
953 | ||
954 | if (object_sizes[0]) | |
955 | return; | |
956 | ||
957 | for (object_size_type = 0; object_size_type <= 3; object_size_type++) | |
958 | { | |
4c36ffe6 | 959 | object_sizes[object_size_type] = XNEWVEC (unsigned HOST_WIDE_INT, num_ssa_names); |
0a39fd54 | 960 | computed[object_size_type] = BITMAP_ALLOC (NULL); |
961 | } | |
962 | ||
963 | init_offset_limit (); | |
964 | } | |
965 | ||
966 | ||
967 | /* Destroy data structures after the object size computation. */ | |
968 | ||
969 | void | |
970 | fini_object_sizes (void) | |
971 | { | |
972 | int object_size_type; | |
973 | ||
974 | for (object_size_type = 0; object_size_type <= 3; object_size_type++) | |
975 | { | |
976 | free (object_sizes[object_size_type]); | |
977 | BITMAP_FREE (computed[object_size_type]); | |
978 | object_sizes[object_size_type] = NULL; | |
979 | } | |
980 | } | |
981 | ||
982 | ||
983 | /* Simple pass to optimize all __builtin_object_size () builtins. */ | |
984 | ||
2a1990e9 | 985 | static unsigned int |
0a39fd54 | 986 | compute_object_sizes (void) |
987 | { | |
988 | basic_block bb; | |
989 | FOR_EACH_BB (bb) | |
990 | { | |
991 | block_stmt_iterator i; | |
992 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
993 | { | |
994 | tree *stmtp = bsi_stmt_ptr (i); | |
995 | tree call = get_rhs (*stmtp); | |
996 | tree callee, result; | |
997 | ||
998 | if (!call || TREE_CODE (call) != CALL_EXPR) | |
999 | continue; | |
1000 | ||
1001 | callee = get_callee_fndecl (call); | |
1002 | if (!callee | |
1003 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
1004 | || DECL_FUNCTION_CODE (callee) != BUILT_IN_OBJECT_SIZE) | |
1005 | continue; | |
1006 | ||
1007 | init_object_sizes (); | |
1008 | result = fold_builtin (callee, TREE_OPERAND (call, 1), false); | |
1009 | if (!result) | |
1010 | { | |
1011 | tree arglist = TREE_OPERAND (call, 1); | |
1012 | ||
1013 | if (arglist != NULL | |
1014 | && POINTER_TYPE_P (TREE_TYPE (TREE_VALUE (arglist))) | |
1015 | && TREE_CHAIN (arglist) != NULL | |
1016 | && TREE_CHAIN (TREE_CHAIN (arglist)) == NULL) | |
1017 | { | |
1018 | tree ost = TREE_VALUE (TREE_CHAIN (arglist)); | |
1019 | ||
1020 | if (host_integerp (ost, 1)) | |
1021 | { | |
1022 | unsigned HOST_WIDE_INT object_size_type | |
1023 | = tree_low_cst (ost, 1); | |
1024 | ||
1025 | if (object_size_type < 2) | |
1026 | result = fold_convert (size_type_node, | |
1027 | integer_minus_one_node); | |
1028 | else if (object_size_type < 4) | |
1029 | result = size_zero_node; | |
1030 | } | |
1031 | } | |
1032 | ||
1033 | if (!result) | |
1034 | continue; | |
1035 | } | |
1036 | ||
1037 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1038 | { | |
1039 | fprintf (dump_file, "Simplified\n "); | |
1040 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
1041 | } | |
1042 | ||
1043 | if (!set_rhs (stmtp, result)) | |
6276113b | 1044 | gcc_unreachable (); |
0a39fd54 | 1045 | update_stmt (*stmtp); |
1046 | ||
1047 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1048 | { | |
1049 | fprintf (dump_file, "to\n "); | |
1050 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
1051 | fprintf (dump_file, "\n"); | |
1052 | } | |
1053 | } | |
1054 | } | |
1055 | ||
1056 | fini_object_sizes (); | |
2a1990e9 | 1057 | return 0; |
0a39fd54 | 1058 | } |
1059 | ||
1060 | struct tree_opt_pass pass_object_sizes = | |
1061 | { | |
1062 | "objsz", /* name */ | |
1063 | NULL, /* gate */ | |
1064 | compute_object_sizes, /* execute */ | |
1065 | NULL, /* sub */ | |
1066 | NULL, /* next */ | |
1067 | 0, /* static_pass_number */ | |
1068 | 0, /* tv_id */ | |
1069 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
1070 | 0, /* properties_provided */ | |
1071 | 0, /* properties_destroyed */ | |
1072 | 0, /* todo_flags_start */ | |
1073 | TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */ | |
1074 | 0 /* letter */ | |
1075 | }; |