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34f97b94 | 1 | /* Predicate aware uninitialized variable warning. |
cf835838 | 2 | Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2010 Free Software |
34f97b94 XDL |
3 | Foundation, Inc. |
4 | Contributed by Xinliang David Li <davidxl@google.com> | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
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) | |
11 | any later version. | |
12 | ||
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. | |
17 | ||
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/>. */ | |
21 | ||
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "tree.h" | |
27 | #include "flags.h" | |
34f97b94 | 28 | #include "tm_p.h" |
34f97b94 | 29 | #include "langhooks.h" |
34f97b94 XDL |
30 | #include "basic-block.h" |
31 | #include "output.h" | |
34f97b94 | 32 | #include "function.h" |
cf835838 | 33 | #include "gimple-pretty-print.h" |
34f97b94 XDL |
34 | #include "bitmap.h" |
35 | #include "pointer-set.h" | |
36 | #include "tree-flow.h" | |
37 | #include "gimple.h" | |
38 | #include "tree-inline.h" | |
34f97b94 XDL |
39 | #include "timevar.h" |
40 | #include "hashtab.h" | |
41 | #include "tree-dump.h" | |
42 | #include "tree-pass.h" | |
718f9c0f | 43 | #include "diagnostic-core.h" |
34f97b94 XDL |
44 | #include "toplev.h" |
45 | #include "timevar.h" | |
46 | ||
47 | /* This implements the pass that does predicate aware warning on uses of | |
48 | possibly uninitialized variables. The pass first collects the set of | |
49 | possibly uninitialized SSA names. For each such name, it walks through | |
50 | all its immediate uses. For each immediate use, it rebuilds the condition | |
51 | expression (the predicate) that guards the use. The predicate is then | |
52 | examined to see if the variable is always defined under that same condition. | |
53 | This is done either by pruning the unrealizable paths that lead to the | |
54 | default definitions or by checking if the predicate set that guards the | |
55 | defining paths is a superset of the use predicate. */ | |
56 | ||
57 | ||
58 | /* Pointer set of potentially undefined ssa names, i.e., | |
59 | ssa names that are defined by phi with operands that | |
60 | are not defined or potentially undefined. */ | |
61 | static struct pointer_set_t *possibly_undefined_names = 0; | |
62 | ||
63 | /* Bit mask handling macros. */ | |
64 | #define MASK_SET_BIT(mask, pos) mask |= (1 << pos) | |
65 | #define MASK_TEST_BIT(mask, pos) (mask & (1 << pos)) | |
66 | #define MASK_EMPTY(mask) (mask == 0) | |
67 | ||
68 | /* Returns the first bit position (starting from LSB) | |
69 | in mask that is non zero. Returns -1 if the mask is empty. */ | |
70 | static int | |
71 | get_mask_first_set_bit (unsigned mask) | |
72 | { | |
73 | int pos = 0; | |
74 | if (mask == 0) | |
75 | return -1; | |
76 | ||
77 | while ((mask & (1 << pos)) == 0) | |
78 | pos++; | |
79 | ||
80 | return pos; | |
81 | } | |
82 | #define MASK_FIRST_SET_BIT(mask) get_mask_first_set_bit (mask) | |
83 | ||
84 | ||
85 | /* Return true if T, an SSA_NAME, has an undefined value. */ | |
86 | ||
87 | bool | |
88 | ssa_undefined_value_p (tree t) | |
89 | { | |
90 | tree var = SSA_NAME_VAR (t); | |
91 | ||
92 | /* Parameters get their initial value from the function entry. */ | |
93 | if (TREE_CODE (var) == PARM_DECL) | |
94 | return false; | |
95 | ||
6938f93f JH |
96 | /* When returning by reference the return address is actually a hidden |
97 | parameter. */ | |
98 | if (TREE_CODE (SSA_NAME_VAR (t)) == RESULT_DECL | |
99 | && DECL_BY_REFERENCE (SSA_NAME_VAR (t))) | |
100 | return false; | |
101 | ||
34f97b94 XDL |
102 | /* Hard register variables get their initial value from the ether. */ |
103 | if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var)) | |
104 | return false; | |
105 | ||
106 | /* The value is undefined iff its definition statement is empty. */ | |
107 | return (gimple_nop_p (SSA_NAME_DEF_STMT (t)) | |
108 | || (possibly_undefined_names | |
109 | && pointer_set_contains (possibly_undefined_names, t))); | |
110 | } | |
111 | ||
112 | /* Checks if the operand OPND of PHI is defined by | |
113 | another phi with one operand defined by this PHI, | |
114 | but the rest operands are all defined. If yes, | |
115 | returns true to skip this this operand as being | |
116 | redundant. Can be enhanced to be more general. */ | |
117 | ||
118 | static bool | |
119 | can_skip_redundant_opnd (tree opnd, gimple phi) | |
120 | { | |
121 | gimple op_def; | |
122 | tree phi_def; | |
123 | int i, n; | |
124 | ||
125 | phi_def = gimple_phi_result (phi); | |
126 | op_def = SSA_NAME_DEF_STMT (opnd); | |
127 | if (gimple_code (op_def) != GIMPLE_PHI) | |
128 | return false; | |
129 | n = gimple_phi_num_args (op_def); | |
130 | for (i = 0; i < n; ++i) | |
131 | { | |
132 | tree op = gimple_phi_arg_def (op_def, i); | |
133 | if (TREE_CODE (op) != SSA_NAME) | |
134 | continue; | |
135 | if (op != phi_def && ssa_undefined_value_p (op)) | |
136 | return false; | |
137 | } | |
138 | ||
139 | return true; | |
140 | } | |
141 | ||
142 | /* Returns a bit mask holding the positions of arguments in PHI | |
143 | that have empty (or possibly empty) definitions. */ | |
144 | ||
145 | static unsigned | |
146 | compute_uninit_opnds_pos (gimple phi) | |
147 | { | |
148 | size_t i, n; | |
149 | unsigned uninit_opnds = 0; | |
150 | ||
151 | n = gimple_phi_num_args (phi); | |
98d30e4f XDL |
152 | /* Bail out for phi with too many args. */ |
153 | if (n > 32) | |
154 | return 0; | |
34f97b94 XDL |
155 | |
156 | for (i = 0; i < n; ++i) | |
157 | { | |
158 | tree op = gimple_phi_arg_def (phi, i); | |
159 | if (TREE_CODE (op) == SSA_NAME | |
160 | && ssa_undefined_value_p (op) | |
161 | && !can_skip_redundant_opnd (op, phi)) | |
162 | MASK_SET_BIT (uninit_opnds, i); | |
163 | } | |
164 | return uninit_opnds; | |
165 | } | |
166 | ||
167 | /* Find the immediate postdominator PDOM of the specified | |
168 | basic block BLOCK. */ | |
169 | ||
170 | static inline basic_block | |
171 | find_pdom (basic_block block) | |
172 | { | |
173 | if (block == EXIT_BLOCK_PTR) | |
174 | return EXIT_BLOCK_PTR; | |
175 | else | |
176 | { | |
177 | basic_block bb | |
178 | = get_immediate_dominator (CDI_POST_DOMINATORS, block); | |
179 | if (! bb) | |
180 | return EXIT_BLOCK_PTR; | |
181 | return bb; | |
182 | } | |
183 | } | |
184 | ||
185 | /* Find the immediate DOM of the specified | |
186 | basic block BLOCK. */ | |
187 | ||
188 | static inline basic_block | |
189 | find_dom (basic_block block) | |
190 | { | |
191 | if (block == ENTRY_BLOCK_PTR) | |
192 | return ENTRY_BLOCK_PTR; | |
193 | else | |
194 | { | |
195 | basic_block bb = get_immediate_dominator (CDI_DOMINATORS, block); | |
196 | if (! bb) | |
197 | return ENTRY_BLOCK_PTR; | |
198 | return bb; | |
199 | } | |
200 | } | |
201 | ||
202 | /* Returns true if BB1 is postdominating BB2 and BB1 is | |
203 | not a loop exit bb. The loop exit bb check is simple and does | |
204 | not cover all cases. */ | |
205 | ||
206 | static bool | |
207 | is_non_loop_exit_postdominating (basic_block bb1, basic_block bb2) | |
208 | { | |
209 | if (!dominated_by_p (CDI_POST_DOMINATORS, bb2, bb1)) | |
210 | return false; | |
211 | ||
212 | if (single_pred_p (bb1) && !single_succ_p (bb2)) | |
213 | return false; | |
214 | ||
215 | return true; | |
216 | } | |
217 | ||
218 | /* Find the closest postdominator of a specified BB, which is control | |
219 | equivalent to BB. */ | |
220 | ||
221 | static inline basic_block | |
222 | find_control_equiv_block (basic_block bb) | |
223 | { | |
224 | basic_block pdom; | |
225 | ||
226 | pdom = find_pdom (bb); | |
227 | ||
228 | /* Skip the postdominating bb that is also loop exit. */ | |
229 | if (!is_non_loop_exit_postdominating (pdom, bb)) | |
230 | return NULL; | |
231 | ||
232 | if (dominated_by_p (CDI_DOMINATORS, pdom, bb)) | |
233 | return pdom; | |
234 | ||
235 | return NULL; | |
236 | } | |
237 | ||
238 | #define MAX_NUM_CHAINS 8 | |
239 | #define MAX_CHAIN_LEN 5 | |
240 | ||
241 | /* Computes the control dependence chains (paths of edges) | |
242 | for DEP_BB up to the dominating basic block BB (the head node of a | |
243 | chain should be dominated by it). CD_CHAINS is pointer to a | |
244 | dynamic array holding the result chains. CUR_CD_CHAIN is the current | |
245 | chain being computed. *NUM_CHAINS is total number of chains. The | |
246 | function returns true if the information is successfully computed, | |
247 | return false if there is no control dependence or not computed. */ | |
248 | ||
249 | static bool | |
250 | compute_control_dep_chain (basic_block bb, basic_block dep_bb, | |
251 | VEC(edge, heap) **cd_chains, | |
252 | size_t *num_chains, | |
253 | VEC(edge, heap) **cur_cd_chain) | |
254 | { | |
255 | edge_iterator ei; | |
256 | edge e; | |
257 | size_t i; | |
258 | bool found_cd_chain = false; | |
259 | size_t cur_chain_len = 0; | |
260 | ||
261 | if (EDGE_COUNT (bb->succs) < 2) | |
262 | return false; | |
263 | ||
264 | /* Could use a set instead. */ | |
265 | cur_chain_len = VEC_length (edge, *cur_cd_chain); | |
266 | if (cur_chain_len > MAX_CHAIN_LEN) | |
267 | return false; | |
268 | ||
269 | for (i = 0; i < cur_chain_len; i++) | |
270 | { | |
271 | edge e = VEC_index (edge, *cur_cd_chain, i); | |
272 | /* cycle detected. */ | |
273 | if (e->src == bb) | |
274 | return false; | |
275 | } | |
276 | ||
277 | FOR_EACH_EDGE (e, ei, bb->succs) | |
278 | { | |
279 | basic_block cd_bb; | |
280 | if (e->flags & (EDGE_FAKE | EDGE_ABNORMAL)) | |
281 | continue; | |
282 | ||
283 | cd_bb = e->dest; | |
284 | VEC_safe_push (edge, heap, *cur_cd_chain, e); | |
285 | while (!is_non_loop_exit_postdominating (cd_bb, bb)) | |
286 | { | |
287 | if (cd_bb == dep_bb) | |
288 | { | |
289 | /* Found a direct control dependence. */ | |
290 | if (*num_chains < MAX_NUM_CHAINS) | |
291 | { | |
292 | cd_chains[*num_chains] | |
293 | = VEC_copy (edge, heap, *cur_cd_chain); | |
294 | (*num_chains)++; | |
295 | } | |
296 | found_cd_chain = true; | |
297 | /* check path from next edge. */ | |
298 | break; | |
299 | } | |
300 | ||
301 | /* Now check if DEP_BB is indirectly control dependent on BB. */ | |
302 | if (compute_control_dep_chain (cd_bb, dep_bb, cd_chains, | |
303 | num_chains, cur_cd_chain)) | |
304 | { | |
305 | found_cd_chain = true; | |
306 | break; | |
307 | } | |
308 | ||
309 | cd_bb = find_pdom (cd_bb); | |
310 | if (cd_bb == EXIT_BLOCK_PTR) | |
311 | break; | |
312 | } | |
313 | VEC_pop (edge, *cur_cd_chain); | |
314 | gcc_assert (VEC_length (edge, *cur_cd_chain) == cur_chain_len); | |
315 | } | |
316 | gcc_assert (VEC_length (edge, *cur_cd_chain) == cur_chain_len); | |
317 | ||
318 | return found_cd_chain; | |
319 | } | |
320 | ||
321 | typedef struct use_pred_info | |
322 | { | |
323 | gimple cond; | |
324 | bool invert; | |
325 | } *use_pred_info_t; | |
326 | ||
327 | DEF_VEC_P(use_pred_info_t); | |
328 | DEF_VEC_ALLOC_P(use_pred_info_t, heap); | |
329 | ||
330 | ||
331 | /* Converts the chains of control dependence edges into a set of | |
332 | predicates. A control dependence chain is represented by a vector | |
333 | edges. DEP_CHAINS points to an array of dependence chains. | |
334 | NUM_CHAINS is the size of the chain array. One edge in a dependence | |
335 | chain is mapped to predicate expression represented by use_pred_info_t | |
336 | type. One dependence chain is converted to a composite predicate that | |
337 | is the result of AND operation of use_pred_info_t mapped to each edge. | |
338 | A composite predicate is presented by a vector of use_pred_info_t. On | |
339 | return, *PREDS points to the resulting array of composite predicates. | |
340 | *NUM_PREDS is the number of composite predictes. */ | |
341 | ||
342 | static bool | |
343 | convert_control_dep_chain_into_preds (VEC(edge, heap) **dep_chains, | |
344 | size_t num_chains, | |
345 | VEC(use_pred_info_t, heap) ***preds, | |
346 | size_t *num_preds) | |
347 | { | |
348 | bool has_valid_pred = false; | |
349 | size_t i, j; | |
350 | if (num_chains == 0 || num_chains >= MAX_NUM_CHAINS) | |
351 | return false; | |
352 | ||
353 | /* Now convert CD chains into predicates */ | |
354 | has_valid_pred = true; | |
355 | ||
356 | /* Now convert the control dep chain into a set | |
357 | of predicates. */ | |
358 | *preds = XCNEWVEC (VEC(use_pred_info_t, heap) *, | |
359 | num_chains); | |
360 | *num_preds = num_chains; | |
361 | ||
362 | for (i = 0; i < num_chains; i++) | |
363 | { | |
364 | VEC(edge, heap) *one_cd_chain = dep_chains[i]; | |
365 | for (j = 0; j < VEC_length (edge, one_cd_chain); j++) | |
366 | { | |
367 | gimple cond_stmt; | |
368 | gimple_stmt_iterator gsi; | |
369 | basic_block guard_bb; | |
370 | use_pred_info_t one_pred; | |
371 | edge e; | |
372 | ||
373 | e = VEC_index (edge, one_cd_chain, j); | |
374 | guard_bb = e->src; | |
375 | gsi = gsi_last_bb (guard_bb); | |
376 | if (gsi_end_p (gsi)) | |
377 | { | |
378 | has_valid_pred = false; | |
379 | break; | |
380 | } | |
381 | cond_stmt = gsi_stmt (gsi); | |
382 | if (gimple_code (cond_stmt) == GIMPLE_CALL | |
383 | && EDGE_COUNT (e->src->succs) >= 2) | |
384 | { | |
385 | /* Ignore EH edge. Can add assertion | |
386 | on the other edge's flag. */ | |
387 | continue; | |
388 | } | |
389 | /* Skip if there is essentially one succesor. */ | |
390 | if (EDGE_COUNT (e->src->succs) == 2) | |
391 | { | |
392 | edge e1; | |
393 | edge_iterator ei1; | |
394 | bool skip = false; | |
395 | ||
396 | FOR_EACH_EDGE (e1, ei1, e->src->succs) | |
397 | { | |
398 | if (EDGE_COUNT (e1->dest->succs) == 0) | |
399 | { | |
400 | skip = true; | |
401 | break; | |
402 | } | |
403 | } | |
404 | if (skip) | |
405 | continue; | |
406 | } | |
407 | if (gimple_code (cond_stmt) != GIMPLE_COND) | |
408 | { | |
409 | has_valid_pred = false; | |
410 | break; | |
411 | } | |
412 | one_pred = XNEW (struct use_pred_info); | |
413 | one_pred->cond = cond_stmt; | |
414 | one_pred->invert = !!(e->flags & EDGE_FALSE_VALUE); | |
415 | VEC_safe_push (use_pred_info_t, heap, (*preds)[i], one_pred); | |
416 | } | |
417 | ||
418 | if (!has_valid_pred) | |
419 | break; | |
420 | } | |
421 | return has_valid_pred; | |
422 | } | |
423 | ||
424 | /* Computes all control dependence chains for USE_BB. The control | |
425 | dependence chains are then converted to an array of composite | |
426 | predicates pointed to by PREDS. PHI_BB is the basic block of | |
427 | the phi whose result is used in USE_BB. */ | |
428 | ||
429 | static bool | |
430 | find_predicates (VEC(use_pred_info_t, heap) ***preds, | |
431 | size_t *num_preds, | |
432 | basic_block phi_bb, | |
433 | basic_block use_bb) | |
434 | { | |
435 | size_t num_chains = 0, i; | |
436 | VEC(edge, heap) **dep_chains = 0; | |
437 | VEC(edge, heap) *cur_chain = 0; | |
438 | bool has_valid_pred = false; | |
439 | basic_block cd_root = 0; | |
440 | ||
441 | dep_chains = XCNEWVEC (VEC(edge, heap) *, MAX_NUM_CHAINS); | |
442 | ||
443 | /* First find the closest bb that is control equivalent to PHI_BB | |
444 | that also dominates USE_BB. */ | |
445 | cd_root = phi_bb; | |
446 | while (dominated_by_p (CDI_DOMINATORS, use_bb, cd_root)) | |
447 | { | |
448 | basic_block ctrl_eq_bb = find_control_equiv_block (cd_root); | |
449 | if (ctrl_eq_bb && dominated_by_p (CDI_DOMINATORS, use_bb, ctrl_eq_bb)) | |
450 | cd_root = ctrl_eq_bb; | |
451 | else | |
452 | break; | |
453 | } | |
454 | ||
455 | compute_control_dep_chain (cd_root, use_bb, | |
456 | dep_chains, &num_chains, | |
457 | &cur_chain); | |
458 | ||
459 | has_valid_pred | |
460 | = convert_control_dep_chain_into_preds (dep_chains, | |
461 | num_chains, | |
462 | preds, | |
463 | num_preds); | |
464 | /* Free individual chain */ | |
465 | VEC_free (edge, heap, cur_chain); | |
466 | for (i = 0; i < num_chains; i++) | |
467 | VEC_free (edge, heap, dep_chains[i]); | |
468 | free (dep_chains); | |
469 | return has_valid_pred; | |
470 | } | |
471 | ||
472 | /* Computes the set of incoming edges of PHI that have non empty | |
473 | definitions of a phi chain. The collection will be done | |
474 | recursively on operands that are defined by phis. CD_ROOT | |
475 | is the control dependence root. *EDGES holds the result, and | |
476 | VISITED_PHIS is a pointer set for detecting cycles. */ | |
477 | ||
478 | static void | |
479 | collect_phi_def_edges (gimple phi, basic_block cd_root, | |
480 | VEC(edge, heap) **edges, | |
481 | struct pointer_set_t *visited_phis) | |
482 | { | |
483 | size_t i, n; | |
484 | edge opnd_edge; | |
485 | tree opnd; | |
486 | ||
487 | if (pointer_set_insert (visited_phis, phi)) | |
488 | return; | |
489 | ||
490 | n = gimple_phi_num_args (phi); | |
491 | for (i = 0; i < n; i++) | |
492 | { | |
493 | opnd_edge = gimple_phi_arg_edge (phi, i); | |
494 | opnd = gimple_phi_arg_def (phi, i); | |
495 | ||
e74780a3 XDL |
496 | if (TREE_CODE (opnd) != SSA_NAME) |
497 | { | |
498 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
499 | { | |
500 | fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i); | |
501 | print_gimple_stmt (dump_file, phi, 0, 0); | |
502 | } | |
503 | VEC_safe_push (edge, heap, *edges, opnd_edge); | |
504 | } | |
34f97b94 XDL |
505 | else |
506 | { | |
507 | gimple def = SSA_NAME_DEF_STMT (opnd); | |
e74780a3 | 508 | |
34f97b94 XDL |
509 | if (gimple_code (def) == GIMPLE_PHI |
510 | && dominated_by_p (CDI_DOMINATORS, | |
511 | gimple_bb (def), cd_root)) | |
512 | collect_phi_def_edges (def, cd_root, edges, | |
513 | visited_phis); | |
e74780a3 XDL |
514 | else if (!ssa_undefined_value_p (opnd)) |
515 | { | |
516 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
517 | { | |
518 | fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i); | |
519 | print_gimple_stmt (dump_file, phi, 0, 0); | |
520 | } | |
521 | VEC_safe_push (edge, heap, *edges, opnd_edge); | |
522 | } | |
34f97b94 XDL |
523 | } |
524 | } | |
525 | } | |
526 | ||
527 | /* For each use edge of PHI, computes all control dependence chains. | |
528 | The control dependence chains are then converted to an array of | |
529 | composite predicates pointed to by PREDS. */ | |
530 | ||
531 | static bool | |
532 | find_def_preds (VEC(use_pred_info_t, heap) ***preds, | |
533 | size_t *num_preds, gimple phi) | |
534 | { | |
535 | size_t num_chains = 0, i, n; | |
536 | VEC(edge, heap) **dep_chains = 0; | |
537 | VEC(edge, heap) *cur_chain = 0; | |
538 | VEC(edge, heap) *def_edges = 0; | |
539 | bool has_valid_pred = false; | |
540 | basic_block phi_bb, cd_root = 0; | |
541 | struct pointer_set_t *visited_phis; | |
542 | ||
543 | dep_chains = XCNEWVEC (VEC(edge, heap) *, MAX_NUM_CHAINS); | |
544 | ||
545 | phi_bb = gimple_bb (phi); | |
546 | /* First find the closest dominating bb to be | |
547 | the control dependence root */ | |
548 | cd_root = find_dom (phi_bb); | |
549 | if (!cd_root) | |
550 | return false; | |
551 | ||
552 | visited_phis = pointer_set_create (); | |
553 | collect_phi_def_edges (phi, cd_root, &def_edges, visited_phis); | |
554 | pointer_set_destroy (visited_phis); | |
555 | ||
556 | n = VEC_length (edge, def_edges); | |
557 | if (n == 0) | |
558 | return false; | |
559 | ||
560 | for (i = 0; i < n; i++) | |
561 | { | |
562 | size_t prev_nc, j; | |
563 | edge opnd_edge; | |
564 | ||
565 | opnd_edge = VEC_index (edge, def_edges, i); | |
566 | prev_nc = num_chains; | |
567 | compute_control_dep_chain (cd_root, opnd_edge->src, | |
568 | dep_chains, &num_chains, | |
569 | &cur_chain); | |
570 | /* Free individual chain */ | |
571 | VEC_free (edge, heap, cur_chain); | |
572 | cur_chain = 0; | |
573 | ||
574 | /* Now update the newly added chains with | |
575 | the phi operand edge: */ | |
576 | if (EDGE_COUNT (opnd_edge->src->succs) > 1) | |
577 | { | |
578 | if (prev_nc == num_chains | |
579 | && num_chains < MAX_NUM_CHAINS) | |
580 | num_chains++; | |
581 | for (j = prev_nc; j < num_chains; j++) | |
582 | { | |
583 | VEC_safe_push (edge, heap, dep_chains[j], opnd_edge); | |
584 | } | |
585 | } | |
586 | } | |
587 | ||
588 | has_valid_pred | |
589 | = convert_control_dep_chain_into_preds (dep_chains, | |
590 | num_chains, | |
591 | preds, | |
592 | num_preds); | |
593 | for (i = 0; i < num_chains; i++) | |
594 | VEC_free (edge, heap, dep_chains[i]); | |
595 | free (dep_chains); | |
596 | return has_valid_pred; | |
597 | } | |
598 | ||
599 | /* Dumps the predicates (PREDS) for USESTMT. */ | |
600 | ||
601 | static void | |
602 | dump_predicates (gimple usestmt, size_t num_preds, | |
603 | VEC(use_pred_info_t, heap) **preds, | |
604 | const char* msg) | |
605 | { | |
606 | size_t i, j; | |
607 | VEC(use_pred_info_t, heap) *one_pred_chain; | |
608 | fprintf (dump_file, msg); | |
609 | print_gimple_stmt (dump_file, usestmt, 0, 0); | |
610 | fprintf (dump_file, "is guarded by :\n"); | |
611 | /* do some dumping here: */ | |
612 | for (i = 0; i < num_preds; i++) | |
613 | { | |
614 | size_t np; | |
615 | ||
616 | one_pred_chain = preds[i]; | |
617 | np = VEC_length (use_pred_info_t, one_pred_chain); | |
618 | ||
619 | for (j = 0; j < np; j++) | |
620 | { | |
621 | use_pred_info_t one_pred | |
622 | = VEC_index (use_pred_info_t, one_pred_chain, j); | |
623 | if (one_pred->invert) | |
624 | fprintf (dump_file, " (.NOT.) "); | |
625 | print_gimple_stmt (dump_file, one_pred->cond, 0, 0); | |
626 | if (j < np - 1) | |
627 | fprintf (dump_file, "(.AND.)\n"); | |
628 | } | |
629 | if (i < num_preds - 1) | |
630 | fprintf (dump_file, "(.OR.)\n"); | |
631 | } | |
632 | } | |
633 | ||
634 | /* Destroys the predicate set *PREDS. */ | |
635 | ||
636 | static void | |
637 | destroy_predicate_vecs (size_t n, | |
638 | VEC(use_pred_info_t, heap) ** preds) | |
639 | { | |
640 | size_t i, j; | |
641 | for (i = 0; i < n; i++) | |
642 | { | |
643 | for (j = 0; j < VEC_length (use_pred_info_t, preds[i]); j++) | |
644 | free (VEC_index (use_pred_info_t, preds[i], j)); | |
645 | VEC_free (use_pred_info_t, heap, preds[i]); | |
646 | } | |
647 | free (preds); | |
648 | } | |
649 | ||
650 | ||
651 | /* Computes the 'normalized' conditional code with operand | |
652 | swapping and condition inversion. */ | |
653 | ||
654 | static enum tree_code | |
655 | get_cmp_code (enum tree_code orig_cmp_code, | |
656 | bool swap_cond, bool invert) | |
657 | { | |
658 | enum tree_code tc = orig_cmp_code; | |
659 | ||
660 | if (swap_cond) | |
661 | tc = swap_tree_comparison (orig_cmp_code); | |
662 | if (invert) | |
663 | tc = invert_tree_comparison (tc, false); | |
664 | ||
665 | switch (tc) | |
666 | { | |
667 | case LT_EXPR: | |
668 | case LE_EXPR: | |
669 | case GT_EXPR: | |
670 | case GE_EXPR: | |
671 | case EQ_EXPR: | |
672 | case NE_EXPR: | |
673 | break; | |
674 | default: | |
675 | return ERROR_MARK; | |
676 | } | |
677 | return tc; | |
678 | } | |
679 | ||
680 | /* Returns true if VAL falls in the range defined by BOUNDARY and CMPC, i.e. | |
681 | all values in the range satisfies (x CMPC BOUNDARY) == true. */ | |
682 | ||
683 | static bool | |
684 | is_value_included_in (tree val, tree boundary, enum tree_code cmpc) | |
685 | { | |
686 | bool inverted = false; | |
687 | bool is_unsigned; | |
688 | bool result; | |
689 | ||
690 | /* Only handle integer constant here. */ | |
691 | if (TREE_CODE (val) != INTEGER_CST | |
692 | || TREE_CODE (boundary) != INTEGER_CST) | |
693 | return true; | |
694 | ||
695 | is_unsigned = TYPE_UNSIGNED (TREE_TYPE (val)); | |
696 | ||
697 | if (cmpc == GE_EXPR || cmpc == GT_EXPR | |
698 | || cmpc == NE_EXPR) | |
699 | { | |
700 | cmpc = invert_tree_comparison (cmpc, false); | |
701 | inverted = true; | |
702 | } | |
703 | ||
704 | if (is_unsigned) | |
705 | { | |
706 | if (cmpc == EQ_EXPR) | |
707 | result = tree_int_cst_equal (val, boundary); | |
708 | else if (cmpc == LT_EXPR) | |
709 | result = INT_CST_LT_UNSIGNED (val, boundary); | |
710 | else | |
711 | { | |
712 | gcc_assert (cmpc == LE_EXPR); | |
713 | result = (tree_int_cst_equal (val, boundary) | |
714 | || INT_CST_LT_UNSIGNED (val, boundary)); | |
715 | } | |
716 | } | |
717 | else | |
718 | { | |
719 | if (cmpc == EQ_EXPR) | |
720 | result = tree_int_cst_equal (val, boundary); | |
721 | else if (cmpc == LT_EXPR) | |
722 | result = INT_CST_LT (val, boundary); | |
723 | else | |
724 | { | |
725 | gcc_assert (cmpc == LE_EXPR); | |
726 | result = (tree_int_cst_equal (val, boundary) | |
727 | || INT_CST_LT (val, boundary)); | |
728 | } | |
729 | } | |
730 | ||
731 | if (inverted) | |
732 | result ^= 1; | |
733 | ||
734 | return result; | |
735 | } | |
736 | ||
737 | /* Returns true if PRED is common among all the predicate | |
738 | chains (PREDS) (and therefore can be factored out). | |
739 | NUM_PRED_CHAIN is the size of array PREDS. */ | |
740 | ||
741 | static bool | |
742 | find_matching_predicate_in_rest_chains (use_pred_info_t pred, | |
743 | VEC(use_pred_info_t, heap) **preds, | |
744 | size_t num_pred_chains) | |
745 | { | |
746 | size_t i, j, n; | |
747 | ||
748 | /* trival case */ | |
749 | if (num_pred_chains == 1) | |
750 | return true; | |
751 | ||
752 | for (i = 1; i < num_pred_chains; i++) | |
753 | { | |
754 | bool found = false; | |
755 | VEC(use_pred_info_t, heap) *one_chain = preds[i]; | |
756 | n = VEC_length (use_pred_info_t, one_chain); | |
757 | for (j = 0; j < n; j++) | |
758 | { | |
759 | use_pred_info_t pred2 | |
760 | = VEC_index (use_pred_info_t, one_chain, j); | |
761 | /* can relax the condition comparison to not | |
762 | use address comparison. However, the most common | |
763 | case is that multiple control dependent paths share | |
764 | a common path prefix, so address comparison should | |
765 | be ok. */ | |
766 | ||
767 | if (pred2->cond == pred->cond | |
768 | && pred2->invert == pred->invert) | |
769 | { | |
770 | found = true; | |
771 | break; | |
772 | } | |
773 | } | |
774 | if (!found) | |
775 | return false; | |
776 | } | |
777 | return true; | |
778 | } | |
779 | ||
780 | /* Forward declaration. */ | |
781 | static bool | |
782 | is_use_properly_guarded (gimple use_stmt, | |
783 | basic_block use_bb, | |
784 | gimple phi, | |
785 | unsigned uninit_opnds, | |
786 | struct pointer_set_t *visited_phis); | |
787 | ||
2edb37a6 XDL |
788 | /* Returns true if all uninitialized opnds are pruned. Returns false |
789 | otherwise. PHI is the phi node with uninitialized operands, | |
790 | UNINIT_OPNDS is the bitmap of the uninitialize operand positions, | |
791 | FLAG_DEF is the statement defining the flag guarding the use of the | |
792 | PHI output, BOUNDARY_CST is the const value used in the predicate | |
793 | associated with the flag, CMP_CODE is the comparison code used in | |
794 | the predicate, VISITED_PHIS is the pointer set of phis visited, and | |
795 | VISITED_FLAG_PHIS is the pointer to the pointer set of flag definitions | |
796 | that are also phis. | |
797 | ||
798 | Example scenario: | |
799 | ||
800 | BB1: | |
801 | flag_1 = phi <0, 1> // (1) | |
802 | var_1 = phi <undef, some_val> | |
803 | ||
804 | ||
805 | BB2: | |
806 | flag_2 = phi <0, flag_1, flag_1> // (2) | |
807 | var_2 = phi <undef, var_1, var_1> | |
808 | if (flag_2 == 1) | |
809 | goto BB3; | |
810 | ||
811 | BB3: | |
812 | use of var_2 // (3) | |
813 | ||
814 | Because some flag arg in (1) is not constant, if we do not look into the | |
815 | flag phis recursively, it is conservatively treated as unknown and var_1 | |
816 | is thought to be flowed into use at (3). Since var_1 is potentially uninitialized | |
817 | a false warning will be emitted. Checking recursively into (1), the compiler can | |
818 | find out that only some_val (which is defined) can flow into (3) which is OK. | |
819 | ||
820 | */ | |
821 | ||
822 | static bool | |
823 | prune_uninit_phi_opnds_in_unrealizable_paths ( | |
824 | gimple phi, unsigned uninit_opnds, | |
825 | gimple flag_def, tree boundary_cst, | |
826 | enum tree_code cmp_code, | |
827 | struct pointer_set_t *visited_phis, | |
828 | bitmap *visited_flag_phis) | |
829 | { | |
830 | unsigned i; | |
831 | ||
832 | for (i = 0; i < MIN (32, gimple_phi_num_args (flag_def)); i++) | |
833 | { | |
834 | tree flag_arg; | |
835 | ||
836 | if (!MASK_TEST_BIT (uninit_opnds, i)) | |
837 | continue; | |
838 | ||
839 | flag_arg = gimple_phi_arg_def (flag_def, i); | |
840 | if (!is_gimple_constant (flag_arg)) | |
841 | { | |
842 | gimple flag_arg_def, phi_arg_def; | |
843 | tree phi_arg; | |
844 | unsigned uninit_opnds_arg_phi; | |
845 | ||
846 | if (TREE_CODE (flag_arg) != SSA_NAME) | |
847 | return false; | |
848 | flag_arg_def = SSA_NAME_DEF_STMT (flag_arg); | |
849 | if (gimple_code (flag_arg_def) != GIMPLE_PHI) | |
850 | return false; | |
851 | ||
852 | phi_arg = gimple_phi_arg_def (phi, i); | |
853 | if (TREE_CODE (phi_arg) != SSA_NAME) | |
854 | return false; | |
855 | ||
856 | phi_arg_def = SSA_NAME_DEF_STMT (phi_arg); | |
857 | if (gimple_code (phi_arg_def) != GIMPLE_PHI) | |
858 | return false; | |
859 | ||
860 | if (gimple_bb (phi_arg_def) != gimple_bb (flag_arg_def)) | |
861 | return false; | |
862 | ||
863 | if (!*visited_flag_phis) | |
864 | *visited_flag_phis = BITMAP_ALLOC (NULL); | |
865 | ||
866 | if (bitmap_bit_p (*visited_flag_phis, | |
867 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)))) | |
868 | return false; | |
869 | ||
870 | bitmap_set_bit (*visited_flag_phis, | |
871 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def))); | |
872 | ||
873 | /* Now recursively prune the uninitialized phi args. */ | |
874 | uninit_opnds_arg_phi = compute_uninit_opnds_pos (phi_arg_def); | |
875 | if (!prune_uninit_phi_opnds_in_unrealizable_paths ( | |
876 | phi_arg_def, uninit_opnds_arg_phi, | |
877 | flag_arg_def, boundary_cst, cmp_code, | |
878 | visited_phis, visited_flag_phis)) | |
879 | return false; | |
880 | ||
881 | bitmap_clear_bit (*visited_flag_phis, | |
882 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def))); | |
883 | continue; | |
884 | } | |
885 | ||
886 | /* Now check if the constant is in the guarded range. */ | |
887 | if (is_value_included_in (flag_arg, boundary_cst, cmp_code)) | |
888 | { | |
889 | tree opnd; | |
890 | gimple opnd_def; | |
891 | ||
892 | /* Now that we know that this undefined edge is not | |
893 | pruned. If the operand is defined by another phi, | |
894 | we can further prune the incoming edges of that | |
895 | phi by checking the predicates of this operands. */ | |
896 | ||
897 | opnd = gimple_phi_arg_def (phi, i); | |
898 | opnd_def = SSA_NAME_DEF_STMT (opnd); | |
899 | if (gimple_code (opnd_def) == GIMPLE_PHI) | |
900 | { | |
901 | edge opnd_edge; | |
902 | unsigned uninit_opnds2 | |
903 | = compute_uninit_opnds_pos (opnd_def); | |
904 | gcc_assert (!MASK_EMPTY (uninit_opnds2)); | |
905 | opnd_edge = gimple_phi_arg_edge (phi, i); | |
906 | if (!is_use_properly_guarded (phi, | |
907 | opnd_edge->src, | |
908 | opnd_def, | |
909 | uninit_opnds2, | |
910 | visited_phis)) | |
911 | return false; | |
912 | } | |
913 | else | |
914 | return false; | |
915 | } | |
916 | } | |
917 | ||
918 | return true; | |
919 | } | |
920 | ||
34f97b94 XDL |
921 | /* A helper function that determines if the predicate set |
922 | of the use is not overlapping with that of the uninit paths. | |
923 | The most common senario of guarded use is in Example 1: | |
924 | Example 1: | |
925 | if (some_cond) | |
926 | { | |
927 | x = ...; | |
928 | flag = true; | |
929 | } | |
930 | ||
931 | ... some code ... | |
932 | ||
933 | if (flag) | |
934 | use (x); | |
935 | ||
936 | The real world examples are usually more complicated, but similar | |
937 | and usually result from inlining: | |
938 | ||
939 | bool init_func (int * x) | |
940 | { | |
941 | if (some_cond) | |
942 | return false; | |
943 | *x = .. | |
944 | return true; | |
945 | } | |
946 | ||
947 | void foo(..) | |
948 | { | |
949 | int x; | |
950 | ||
951 | if (!init_func(&x)) | |
952 | return; | |
953 | ||
954 | .. some_code ... | |
955 | use (x); | |
956 | } | |
957 | ||
958 | Another possible use scenario is in the following trivial example: | |
959 | ||
960 | Example 2: | |
961 | if (n > 0) | |
962 | x = 1; | |
963 | ... | |
964 | if (n > 0) | |
965 | { | |
966 | if (m < 2) | |
967 | .. = x; | |
968 | } | |
969 | ||
970 | Predicate analysis needs to compute the composite predicate: | |
971 | ||
972 | 1) 'x' use predicate: (n > 0) .AND. (m < 2) | |
973 | 2) 'x' default value (non-def) predicate: .NOT. (n > 0) | |
974 | (the predicate chain for phi operand defs can be computed | |
975 | starting from a bb that is control equivalent to the phi's | |
976 | bb and is dominating the operand def.) | |
977 | ||
978 | and check overlapping: | |
979 | (n > 0) .AND. (m < 2) .AND. (.NOT. (n > 0)) | |
980 | <==> false | |
981 | ||
982 | This implementation provides framework that can handle | |
983 | scenarios. (Note that many simple cases are handled properly | |
984 | without the predicate analysis -- this is due to jump threading | |
985 | transformation which eliminates the merge point thus makes | |
986 | path sensitive analysis unnecessary.) | |
987 | ||
988 | NUM_PREDS is the number is the number predicate chains, PREDS is | |
989 | the array of chains, PHI is the phi node whose incoming (undefined) | |
990 | paths need to be pruned, and UNINIT_OPNDS is the bitmap holding | |
991 | uninit operand positions. VISITED_PHIS is the pointer set of phi | |
992 | stmts being checked. */ | |
993 | ||
994 | ||
995 | static bool | |
996 | use_pred_not_overlap_with_undef_path_pred ( | |
997 | size_t num_preds, | |
998 | VEC(use_pred_info_t, heap) **preds, | |
999 | gimple phi, unsigned uninit_opnds, | |
1000 | struct pointer_set_t *visited_phis) | |
1001 | { | |
1002 | unsigned int i, n; | |
1003 | gimple flag_def = 0; | |
1004 | tree boundary_cst = 0; | |
1005 | enum tree_code cmp_code; | |
1006 | bool swap_cond = false; | |
1007 | bool invert = false; | |
1008 | VEC(use_pred_info_t, heap) *the_pred_chain; | |
2edb37a6 XDL |
1009 | bitmap visited_flag_phis = NULL; |
1010 | bool all_pruned = false; | |
34f97b94 XDL |
1011 | |
1012 | gcc_assert (num_preds > 0); | |
1013 | /* Find within the common prefix of multiple predicate chains | |
1014 | a predicate that is a comparison of a flag variable against | |
1015 | a constant. */ | |
1016 | the_pred_chain = preds[0]; | |
1017 | n = VEC_length (use_pred_info_t, the_pred_chain); | |
1018 | for (i = 0; i < n; i++) | |
1019 | { | |
1020 | gimple cond; | |
1021 | tree cond_lhs, cond_rhs, flag = 0; | |
1022 | ||
1023 | use_pred_info_t the_pred | |
1024 | = VEC_index (use_pred_info_t, the_pred_chain, i); | |
1025 | ||
1026 | cond = the_pred->cond; | |
1027 | invert = the_pred->invert; | |
1028 | cond_lhs = gimple_cond_lhs (cond); | |
1029 | cond_rhs = gimple_cond_rhs (cond); | |
1030 | cmp_code = gimple_cond_code (cond); | |
1031 | ||
1032 | if (cond_lhs != NULL_TREE && TREE_CODE (cond_lhs) == SSA_NAME | |
1033 | && cond_rhs != NULL_TREE && is_gimple_constant (cond_rhs)) | |
1034 | { | |
1035 | boundary_cst = cond_rhs; | |
1036 | flag = cond_lhs; | |
1037 | } | |
1038 | else if (cond_rhs != NULL_TREE && TREE_CODE (cond_rhs) == SSA_NAME | |
1039 | && cond_lhs != NULL_TREE && is_gimple_constant (cond_lhs)) | |
1040 | { | |
1041 | boundary_cst = cond_lhs; | |
1042 | flag = cond_rhs; | |
1043 | swap_cond = true; | |
1044 | } | |
1045 | ||
1046 | if (!flag) | |
1047 | continue; | |
1048 | ||
1049 | flag_def = SSA_NAME_DEF_STMT (flag); | |
1050 | ||
1051 | if (!flag_def) | |
1052 | continue; | |
1053 | ||
1054 | if ((gimple_code (flag_def) == GIMPLE_PHI) | |
1055 | && (gimple_bb (flag_def) == gimple_bb (phi)) | |
1056 | && find_matching_predicate_in_rest_chains ( | |
1057 | the_pred, preds, num_preds)) | |
1058 | break; | |
1059 | ||
1060 | flag_def = 0; | |
1061 | } | |
1062 | ||
1063 | if (!flag_def) | |
1064 | return false; | |
1065 | ||
1066 | /* Now check all the uninit incoming edge has a constant flag value | |
1067 | that is in conflict with the use guard/predicate. */ | |
1068 | cmp_code = get_cmp_code (cmp_code, swap_cond, invert); | |
1069 | ||
1070 | if (cmp_code == ERROR_MARK) | |
1071 | return false; | |
1072 | ||
2edb37a6 XDL |
1073 | all_pruned = prune_uninit_phi_opnds_in_unrealizable_paths (phi, |
1074 | uninit_opnds, | |
1075 | flag_def, | |
1076 | boundary_cst, | |
1077 | cmp_code, | |
1078 | visited_phis, | |
1079 | &visited_flag_phis); | |
34f97b94 | 1080 | |
2edb37a6 XDL |
1081 | if (visited_flag_phis) |
1082 | BITMAP_FREE (visited_flag_phis); | |
34f97b94 | 1083 | |
2edb37a6 | 1084 | return all_pruned; |
34f97b94 XDL |
1085 | } |
1086 | ||
1087 | /* Returns true if TC is AND or OR */ | |
1088 | ||
1089 | static inline bool | |
1090 | is_and_or_or (enum tree_code tc, tree typ) | |
1091 | { | |
1092 | return (tc == TRUTH_AND_EXPR | |
1093 | || tc == TRUTH_OR_EXPR | |
1094 | || tc == BIT_IOR_EXPR | |
1095 | || (tc == BIT_AND_EXPR | |
1096 | && (typ == 0 || TREE_CODE (typ) == BOOLEAN_TYPE))); | |
1097 | } | |
1098 | ||
1099 | typedef struct norm_cond | |
1100 | { | |
1101 | VEC(gimple, heap) *conds; | |
1102 | enum tree_code cond_code; | |
1103 | bool invert; | |
1104 | } *norm_cond_t; | |
1105 | ||
1106 | ||
1107 | /* Normalizes gimple condition COND. The normalization follows | |
1108 | UD chains to form larger condition expression trees. NORM_COND | |
1109 | holds the normalized result. COND_CODE is the logical opcode | |
1110 | (AND or OR) of the normalized tree. */ | |
1111 | ||
1112 | static void | |
1113 | normalize_cond_1 (gimple cond, | |
1114 | norm_cond_t norm_cond, | |
1115 | enum tree_code cond_code) | |
1116 | { | |
1117 | enum gimple_code gc; | |
1118 | enum tree_code cur_cond_code; | |
1119 | tree rhs1, rhs2; | |
1120 | ||
1121 | gc = gimple_code (cond); | |
1122 | if (gc != GIMPLE_ASSIGN) | |
1123 | { | |
1124 | VEC_safe_push (gimple, heap, norm_cond->conds, cond); | |
1125 | return; | |
1126 | } | |
1127 | ||
1128 | cur_cond_code = gimple_assign_rhs_code (cond); | |
1129 | rhs1 = gimple_assign_rhs1 (cond); | |
1130 | rhs2 = gimple_assign_rhs2 (cond); | |
1131 | if (cur_cond_code == NE_EXPR) | |
1132 | { | |
1133 | if (integer_zerop (rhs2) | |
1134 | && (TREE_CODE (rhs1) == SSA_NAME)) | |
1135 | normalize_cond_1 ( | |
1136 | SSA_NAME_DEF_STMT (rhs1), | |
1137 | norm_cond, cond_code); | |
1138 | else if (integer_zerop (rhs1) | |
1139 | && (TREE_CODE (rhs2) == SSA_NAME)) | |
1140 | normalize_cond_1 ( | |
1141 | SSA_NAME_DEF_STMT (rhs2), | |
1142 | norm_cond, cond_code); | |
1143 | else | |
1144 | VEC_safe_push (gimple, heap, norm_cond->conds, cond); | |
1145 | ||
1146 | return; | |
1147 | } | |
1148 | ||
1149 | if (is_and_or_or (cur_cond_code, TREE_TYPE (rhs1)) | |
1150 | && (cond_code == cur_cond_code || cond_code == ERROR_MARK) | |
1151 | && (TREE_CODE (rhs1) == SSA_NAME && TREE_CODE (rhs2) == SSA_NAME)) | |
1152 | { | |
1153 | normalize_cond_1 (SSA_NAME_DEF_STMT (rhs1), | |
1154 | norm_cond, cur_cond_code); | |
1155 | normalize_cond_1 (SSA_NAME_DEF_STMT (rhs2), | |
1156 | norm_cond, cur_cond_code); | |
1157 | norm_cond->cond_code = cur_cond_code; | |
1158 | } | |
1159 | else | |
1160 | VEC_safe_push (gimple, heap, norm_cond->conds, cond); | |
1161 | } | |
1162 | ||
1163 | /* See normalize_cond_1 for details. INVERT is a flag to indicate | |
1164 | if COND needs to be inverted or not. */ | |
1165 | ||
1166 | static void | |
1167 | normalize_cond (gimple cond, norm_cond_t norm_cond, bool invert) | |
1168 | { | |
1169 | enum tree_code cond_code; | |
1170 | ||
1171 | norm_cond->cond_code = ERROR_MARK; | |
1172 | norm_cond->invert = false; | |
1173 | norm_cond->conds = NULL; | |
1174 | gcc_assert (gimple_code (cond) == GIMPLE_COND); | |
1175 | cond_code = gimple_cond_code (cond); | |
1176 | if (invert) | |
1177 | cond_code = invert_tree_comparison (cond_code, false); | |
1178 | ||
1179 | if (cond_code == NE_EXPR) | |
1180 | { | |
1181 | if (integer_zerop (gimple_cond_rhs (cond)) | |
1182 | && (TREE_CODE (gimple_cond_lhs (cond)) == SSA_NAME)) | |
1183 | normalize_cond_1 ( | |
1184 | SSA_NAME_DEF_STMT (gimple_cond_lhs (cond)), | |
1185 | norm_cond, ERROR_MARK); | |
1186 | else if (integer_zerop (gimple_cond_lhs (cond)) | |
1187 | && (TREE_CODE (gimple_cond_rhs (cond)) == SSA_NAME)) | |
1188 | normalize_cond_1 ( | |
1189 | SSA_NAME_DEF_STMT (gimple_cond_rhs (cond)), | |
1190 | norm_cond, ERROR_MARK); | |
1191 | else | |
1192 | { | |
1193 | VEC_safe_push (gimple, heap, norm_cond->conds, cond); | |
1194 | norm_cond->invert = invert; | |
1195 | } | |
1196 | } | |
1197 | else | |
1198 | { | |
1199 | VEC_safe_push (gimple, heap, norm_cond->conds, cond); | |
1200 | norm_cond->invert = invert; | |
1201 | } | |
1202 | ||
1203 | gcc_assert (VEC_length (gimple, norm_cond->conds) == 1 | |
1204 | || is_and_or_or (norm_cond->cond_code, NULL)); | |
1205 | } | |
1206 | ||
1207 | /* Returns true if the domain for condition COND1 is a subset of | |
1208 | COND2. REVERSE is a flag. when it is true the function checks | |
1209 | if COND1 is a superset of COND2. INVERT1 and INVERT2 are flags | |
1210 | to indicate if COND1 and COND2 need to be inverted or not. */ | |
1211 | ||
1212 | static bool | |
1213 | is_gcond_subset_of (gimple cond1, bool invert1, | |
1214 | gimple cond2, bool invert2, | |
1215 | bool reverse) | |
1216 | { | |
1217 | enum gimple_code gc1, gc2; | |
1218 | enum tree_code cond1_code, cond2_code; | |
1219 | gimple tmp; | |
1220 | tree cond1_lhs, cond1_rhs, cond2_lhs, cond2_rhs; | |
1221 | ||
1222 | /* Take the short cut. */ | |
1223 | if (cond1 == cond2) | |
1224 | return true; | |
1225 | ||
1226 | if (reverse) | |
1227 | { | |
1228 | tmp = cond1; | |
1229 | cond1 = cond2; | |
1230 | cond2 = tmp; | |
1231 | } | |
1232 | ||
1233 | gc1 = gimple_code (cond1); | |
1234 | gc2 = gimple_code (cond2); | |
1235 | ||
1236 | if ((gc1 != GIMPLE_ASSIGN && gc1 != GIMPLE_COND) | |
1237 | || (gc2 != GIMPLE_ASSIGN && gc2 != GIMPLE_COND)) | |
1238 | return cond1 == cond2; | |
1239 | ||
1240 | cond1_code = ((gc1 == GIMPLE_ASSIGN) | |
1241 | ? gimple_assign_rhs_code (cond1) | |
1242 | : gimple_cond_code (cond1)); | |
1243 | ||
1244 | cond2_code = ((gc2 == GIMPLE_ASSIGN) | |
1245 | ? gimple_assign_rhs_code (cond2) | |
1246 | : gimple_cond_code (cond2)); | |
1247 | ||
1248 | if (TREE_CODE_CLASS (cond1_code) != tcc_comparison | |
1249 | || TREE_CODE_CLASS (cond2_code) != tcc_comparison) | |
1250 | return false; | |
1251 | ||
1252 | if (invert1) | |
1253 | cond1_code = invert_tree_comparison (cond1_code, false); | |
1254 | if (invert2) | |
1255 | cond2_code = invert_tree_comparison (cond2_code, false); | |
1256 | ||
1257 | cond1_lhs = ((gc1 == GIMPLE_ASSIGN) | |
1258 | ? gimple_assign_rhs1 (cond1) | |
1259 | : gimple_cond_lhs (cond1)); | |
1260 | cond1_rhs = ((gc1 == GIMPLE_ASSIGN) | |
1261 | ? gimple_assign_rhs2 (cond1) | |
1262 | : gimple_cond_rhs (cond1)); | |
1263 | cond2_lhs = ((gc2 == GIMPLE_ASSIGN) | |
1264 | ? gimple_assign_rhs1 (cond2) | |
1265 | : gimple_cond_lhs (cond2)); | |
1266 | cond2_rhs = ((gc2 == GIMPLE_ASSIGN) | |
1267 | ? gimple_assign_rhs2 (cond2) | |
1268 | : gimple_cond_rhs (cond2)); | |
1269 | ||
1270 | /* Assuming const operands have been swapped to the | |
1271 | rhs at this point of the analysis. */ | |
1272 | ||
1273 | if (cond1_lhs != cond2_lhs) | |
1274 | return false; | |
1275 | ||
1276 | if (!is_gimple_constant (cond1_rhs) | |
1277 | || TREE_CODE (cond1_rhs) != INTEGER_CST) | |
1278 | return (cond1_rhs == cond2_rhs); | |
1279 | ||
1280 | if (!is_gimple_constant (cond2_rhs) | |
1281 | || TREE_CODE (cond2_rhs) != INTEGER_CST) | |
1282 | return (cond1_rhs == cond2_rhs); | |
1283 | ||
1284 | if (cond1_code == EQ_EXPR) | |
1285 | return is_value_included_in (cond1_rhs, | |
1286 | cond2_rhs, cond2_code); | |
1287 | if (cond1_code == NE_EXPR || cond2_code == EQ_EXPR) | |
1288 | return ((cond2_code == cond1_code) | |
1289 | && tree_int_cst_equal (cond1_rhs, cond2_rhs)); | |
1290 | ||
1291 | if (((cond1_code == GE_EXPR || cond1_code == GT_EXPR) | |
1292 | && (cond2_code == LE_EXPR || cond2_code == LT_EXPR)) | |
1293 | || ((cond1_code == LE_EXPR || cond1_code == LT_EXPR) | |
1294 | && (cond2_code == GE_EXPR || cond2_code == GT_EXPR))) | |
1295 | return false; | |
1296 | ||
1297 | if (cond1_code != GE_EXPR && cond1_code != GT_EXPR | |
1298 | && cond1_code != LE_EXPR && cond1_code != LT_EXPR) | |
1299 | return false; | |
1300 | ||
1301 | if (cond1_code == GT_EXPR) | |
1302 | { | |
1303 | cond1_code = GE_EXPR; | |
1304 | cond1_rhs = fold_binary (PLUS_EXPR, TREE_TYPE (cond1_rhs), | |
1305 | cond1_rhs, | |
1306 | fold_convert (TREE_TYPE (cond1_rhs), | |
1307 | integer_one_node)); | |
1308 | } | |
1309 | else if (cond1_code == LT_EXPR) | |
1310 | { | |
1311 | cond1_code = LE_EXPR; | |
1312 | cond1_rhs = fold_binary (MINUS_EXPR, TREE_TYPE (cond1_rhs), | |
1313 | cond1_rhs, | |
1314 | fold_convert (TREE_TYPE (cond1_rhs), | |
1315 | integer_one_node)); | |
1316 | } | |
1317 | ||
1318 | if (!cond1_rhs) | |
1319 | return false; | |
1320 | ||
1321 | gcc_assert (cond1_code == GE_EXPR || cond1_code == LE_EXPR); | |
1322 | ||
1323 | if (cond2_code == GE_EXPR || cond2_code == GT_EXPR || | |
1324 | cond2_code == LE_EXPR || cond2_code == LT_EXPR) | |
1325 | return is_value_included_in (cond1_rhs, | |
1326 | cond2_rhs, cond2_code); | |
1327 | else if (cond2_code == NE_EXPR) | |
1328 | return | |
1329 | (is_value_included_in (cond1_rhs, | |
1330 | cond2_rhs, cond2_code) | |
1331 | && !is_value_included_in (cond2_rhs, | |
1332 | cond1_rhs, cond1_code)); | |
1333 | return false; | |
1334 | } | |
1335 | ||
1336 | /* Returns true if the domain of the condition expression | |
1337 | in COND is a subset of any of the sub-conditions | |
1338 | of the normalized condtion NORM_COND. INVERT is a flag | |
1339 | to indicate of the COND needs to be inverted. | |
1340 | REVERSE is a flag. When it is true, the check is reversed -- | |
1341 | it returns true if COND is a superset of any of the subconditions | |
1342 | of NORM_COND. */ | |
1343 | ||
1344 | static bool | |
1345 | is_subset_of_any (gimple cond, bool invert, | |
1346 | norm_cond_t norm_cond, bool reverse) | |
1347 | { | |
1348 | size_t i; | |
1349 | size_t len = VEC_length (gimple, norm_cond->conds); | |
1350 | ||
1351 | for (i = 0; i < len; i++) | |
1352 | { | |
1353 | if (is_gcond_subset_of (cond, invert, | |
1354 | VEC_index (gimple, norm_cond->conds, i), | |
1355 | false, reverse)) | |
1356 | return true; | |
1357 | } | |
1358 | return false; | |
1359 | } | |
1360 | ||
1361 | /* NORM_COND1 and NORM_COND2 are normalized logical/BIT OR | |
1362 | expressions (formed by following UD chains not control | |
1363 | dependence chains). The function returns true of domain | |
1364 | of and expression NORM_COND1 is a subset of NORM_COND2's. | |
1365 | The implementation is conservative, and it returns false if | |
1366 | it the inclusion relationship may not hold. */ | |
1367 | ||
1368 | static bool | |
1369 | is_or_set_subset_of (norm_cond_t norm_cond1, | |
1370 | norm_cond_t norm_cond2) | |
1371 | { | |
1372 | size_t i; | |
1373 | size_t len = VEC_length (gimple, norm_cond1->conds); | |
1374 | ||
1375 | for (i = 0; i < len; i++) | |
1376 | { | |
1377 | if (!is_subset_of_any (VEC_index (gimple, norm_cond1->conds, i), | |
1378 | false, norm_cond2, false)) | |
1379 | return false; | |
1380 | } | |
1381 | return true; | |
1382 | } | |
1383 | ||
1384 | /* NORM_COND1 and NORM_COND2 are normalized logical AND | |
1385 | expressions (formed by following UD chains not control | |
1386 | dependence chains). The function returns true of domain | |
1387 | of and expression NORM_COND1 is a subset of NORM_COND2's. */ | |
1388 | ||
1389 | static bool | |
1390 | is_and_set_subset_of (norm_cond_t norm_cond1, | |
1391 | norm_cond_t norm_cond2) | |
1392 | { | |
1393 | size_t i; | |
1394 | size_t len = VEC_length (gimple, norm_cond2->conds); | |
1395 | ||
1396 | for (i = 0; i < len; i++) | |
1397 | { | |
1398 | if (!is_subset_of_any (VEC_index (gimple, norm_cond2->conds, i), | |
1399 | false, norm_cond1, true)) | |
1400 | return false; | |
1401 | } | |
1402 | return true; | |
1403 | } | |
1404 | ||
1405 | /* Returns true of the domain if NORM_COND1 is a subset | |
1406 | of that of NORM_COND2. Returns false if it can not be | |
1407 | proved to be so. */ | |
1408 | ||
1409 | static bool | |
1410 | is_norm_cond_subset_of (norm_cond_t norm_cond1, | |
1411 | norm_cond_t norm_cond2) | |
1412 | { | |
1413 | size_t i; | |
1414 | enum tree_code code1, code2; | |
1415 | ||
1416 | code1 = norm_cond1->cond_code; | |
1417 | code2 = norm_cond2->cond_code; | |
1418 | ||
1419 | if (code1 == TRUTH_AND_EXPR || code1 == BIT_AND_EXPR) | |
1420 | { | |
1421 | /* Both conditions are AND expressions. */ | |
1422 | if (code2 == TRUTH_AND_EXPR || code2 == BIT_AND_EXPR) | |
1423 | return is_and_set_subset_of (norm_cond1, norm_cond2); | |
1424 | /* NORM_COND1 is an AND expression, and NORM_COND2 is an OR | |
1425 | expression. In this case, returns true if any subexpression | |
1426 | of NORM_COND1 is a subset of any subexpression of NORM_COND2. */ | |
1427 | else if (code2 == TRUTH_OR_EXPR || code2 == BIT_IOR_EXPR) | |
1428 | { | |
1429 | size_t len1; | |
1430 | len1 = VEC_length (gimple, norm_cond1->conds); | |
1431 | for (i = 0; i < len1; i++) | |
1432 | { | |
1433 | gimple cond1 = VEC_index (gimple, norm_cond1->conds, i); | |
1434 | if (is_subset_of_any (cond1, false, norm_cond2, false)) | |
1435 | return true; | |
1436 | } | |
1437 | return false; | |
1438 | } | |
1439 | else | |
1440 | { | |
1441 | gcc_assert (code2 == ERROR_MARK); | |
1442 | gcc_assert (VEC_length (gimple, norm_cond2->conds) == 1); | |
1443 | return is_subset_of_any (VEC_index (gimple, norm_cond2->conds, 0), | |
1444 | norm_cond2->invert, norm_cond1, true); | |
1445 | } | |
1446 | } | |
1447 | /* NORM_COND1 is an OR expression */ | |
1448 | else if (code1 == TRUTH_OR_EXPR || code1 == BIT_IOR_EXPR) | |
1449 | { | |
1450 | if (code2 != code1) | |
1451 | return false; | |
1452 | ||
1453 | return is_or_set_subset_of (norm_cond1, norm_cond2); | |
1454 | } | |
1455 | else | |
1456 | { | |
1457 | gcc_assert (code1 == ERROR_MARK); | |
1458 | gcc_assert (VEC_length (gimple, norm_cond1->conds) == 1); | |
1459 | /* Conservatively returns false if NORM_COND1 is non-decomposible | |
1460 | and NORM_COND2 is an AND expression. */ | |
1461 | if (code2 == TRUTH_AND_EXPR || code2 == BIT_AND_EXPR) | |
1462 | return false; | |
1463 | ||
1464 | if (code2 == TRUTH_OR_EXPR || code2 == BIT_IOR_EXPR) | |
1465 | return is_subset_of_any (VEC_index (gimple, norm_cond1->conds, 0), | |
1466 | norm_cond1->invert, norm_cond2, false); | |
1467 | ||
1468 | gcc_assert (code2 == ERROR_MARK); | |
1469 | gcc_assert (VEC_length (gimple, norm_cond2->conds) == 1); | |
1470 | return is_gcond_subset_of (VEC_index (gimple, norm_cond1->conds, 0), | |
1471 | norm_cond1->invert, | |
1472 | VEC_index (gimple, norm_cond2->conds, 0), | |
1473 | norm_cond2->invert, false); | |
1474 | } | |
1475 | } | |
1476 | ||
1477 | /* Returns true of the domain of single predicate expression | |
1478 | EXPR1 is a subset of that of EXPR2. Returns false if it | |
1479 | can not be proved. */ | |
1480 | ||
1481 | static bool | |
1482 | is_pred_expr_subset_of (use_pred_info_t expr1, | |
1483 | use_pred_info_t expr2) | |
1484 | { | |
1485 | gimple cond1, cond2; | |
1486 | enum tree_code code1, code2; | |
1487 | struct norm_cond norm_cond1, norm_cond2; | |
1488 | bool is_subset = false; | |
1489 | ||
1490 | cond1 = expr1->cond; | |
1491 | cond2 = expr2->cond; | |
1492 | code1 = gimple_cond_code (cond1); | |
1493 | code2 = gimple_cond_code (cond2); | |
1494 | ||
1495 | if (expr1->invert) | |
1496 | code1 = invert_tree_comparison (code1, false); | |
1497 | if (expr2->invert) | |
1498 | code2 = invert_tree_comparison (code2, false); | |
1499 | ||
1500 | /* Fast path -- match exactly */ | |
1501 | if ((gimple_cond_lhs (cond1) == gimple_cond_lhs (cond2)) | |
1502 | && (gimple_cond_rhs (cond1) == gimple_cond_rhs (cond2)) | |
1503 | && (code1 == code2)) | |
1504 | return true; | |
1505 | ||
1506 | /* Normalize conditions. To keep NE_EXPR, do not invert | |
1507 | with both need inversion. */ | |
1508 | normalize_cond (cond1, &norm_cond1, (expr1->invert)); | |
1509 | normalize_cond (cond2, &norm_cond2, (expr2->invert)); | |
1510 | ||
1511 | is_subset = is_norm_cond_subset_of (&norm_cond1, &norm_cond2); | |
1512 | ||
1513 | /* Free memory */ | |
1514 | VEC_free (gimple, heap, norm_cond1.conds); | |
1515 | VEC_free (gimple, heap, norm_cond2.conds); | |
1516 | return is_subset ; | |
1517 | } | |
1518 | ||
1519 | /* Returns true if the domain of PRED1 is a subset | |
1520 | of that of PRED2. Returns false if it can not be proved so. */ | |
1521 | ||
1522 | static bool | |
1523 | is_pred_chain_subset_of (VEC(use_pred_info_t, heap) *pred1, | |
1524 | VEC(use_pred_info_t, heap) *pred2) | |
1525 | { | |
1526 | size_t np1, np2, i1, i2; | |
1527 | ||
1528 | np1 = VEC_length (use_pred_info_t, pred1); | |
1529 | np2 = VEC_length (use_pred_info_t, pred2); | |
1530 | ||
1531 | for (i2 = 0; i2 < np2; i2++) | |
1532 | { | |
1533 | bool found = false; | |
1534 | use_pred_info_t info2 | |
1535 | = VEC_index (use_pred_info_t, pred2, i2); | |
1536 | for (i1 = 0; i1 < np1; i1++) | |
1537 | { | |
1538 | use_pred_info_t info1 | |
1539 | = VEC_index (use_pred_info_t, pred1, i1); | |
1540 | if (is_pred_expr_subset_of (info1, info2)) | |
1541 | { | |
1542 | found = true; | |
1543 | break; | |
1544 | } | |
1545 | } | |
1546 | if (!found) | |
1547 | return false; | |
1548 | } | |
1549 | return true; | |
1550 | } | |
1551 | ||
1552 | /* Returns true if the domain defined by | |
1553 | one pred chain ONE_PRED is a subset of the domain | |
1554 | of *PREDS. It returns false if ONE_PRED's domain is | |
1555 | not a subset of any of the sub-domains of PREDS ( | |
1556 | corresponding to each individual chains in it), even | |
1557 | though it may be still be a subset of whole domain | |
1558 | of PREDS which is the union (ORed) of all its subdomains. | |
1559 | In other words, the result is conservative. */ | |
1560 | ||
1561 | static bool | |
1562 | is_included_in (VEC(use_pred_info_t, heap) *one_pred, | |
1563 | VEC(use_pred_info_t, heap) **preds, | |
1564 | size_t n) | |
1565 | { | |
1566 | size_t i; | |
1567 | ||
1568 | for (i = 0; i < n; i++) | |
1569 | { | |
1570 | if (is_pred_chain_subset_of (one_pred, preds[i])) | |
1571 | return true; | |
1572 | } | |
1573 | ||
1574 | return false; | |
1575 | } | |
1576 | ||
1577 | /* compares two predicate sets PREDS1 and PREDS2 and returns | |
1578 | true if the domain defined by PREDS1 is a superset | |
1579 | of PREDS2's domain. N1 and N2 are array sizes of PREDS1 and | |
1580 | PREDS2 respectively. The implementation chooses not to build | |
1581 | generic trees (and relying on the folding capability of the | |
1582 | compiler), but instead performs brute force comparison of | |
1583 | individual predicate chains (won't be a compile time problem | |
1584 | as the chains are pretty short). When the function returns | |
1585 | false, it does not necessarily mean *PREDS1 is not a superset | |
1586 | of *PREDS2, but mean it may not be so since the analysis can | |
1587 | not prove it. In such cases, false warnings may still be | |
1588 | emitted. */ | |
1589 | ||
1590 | static bool | |
1591 | is_superset_of (VEC(use_pred_info_t, heap) **preds1, | |
1592 | size_t n1, | |
1593 | VEC(use_pred_info_t, heap) **preds2, | |
1594 | size_t n2) | |
1595 | { | |
1596 | size_t i; | |
1597 | VEC(use_pred_info_t, heap) *one_pred_chain; | |
1598 | ||
1599 | for (i = 0; i < n2; i++) | |
1600 | { | |
1601 | one_pred_chain = preds2[i]; | |
1602 | if (!is_included_in (one_pred_chain, preds1, n1)) | |
1603 | return false; | |
1604 | } | |
1605 | ||
1606 | return true; | |
1607 | } | |
1608 | ||
1609 | /* Computes the predicates that guard the use and checks | |
1610 | if the incoming paths that have empty (or possibly | |
1611 | empty) defintion can be pruned/filtered. The function returns | |
1612 | true if it can be determined that the use of PHI's def in | |
1613 | USE_STMT is guarded with a predicate set not overlapping with | |
1614 | predicate sets of all runtime paths that do not have a definition. | |
1615 | Returns false if it is not or it can not be determined. USE_BB is | |
1616 | the bb of the use (for phi operand use, the bb is not the bb of | |
1617 | the phi stmt, but the src bb of the operand edge). UNINIT_OPNDS | |
1618 | is a bit vector. If an operand of PHI is uninitialized, the | |
1619 | correponding bit in the vector is 1. VISIED_PHIS is a pointer | |
1620 | set of phis being visted. */ | |
1621 | ||
1622 | static bool | |
1623 | is_use_properly_guarded (gimple use_stmt, | |
1624 | basic_block use_bb, | |
1625 | gimple phi, | |
1626 | unsigned uninit_opnds, | |
1627 | struct pointer_set_t *visited_phis) | |
1628 | { | |
1629 | basic_block phi_bb; | |
1630 | VEC(use_pred_info_t, heap) **preds = 0; | |
1631 | VEC(use_pred_info_t, heap) **def_preds = 0; | |
1632 | size_t num_preds = 0, num_def_preds = 0; | |
1633 | bool has_valid_preds = false; | |
1634 | bool is_properly_guarded = false; | |
1635 | ||
1636 | if (pointer_set_insert (visited_phis, phi)) | |
1637 | return false; | |
1638 | ||
1639 | phi_bb = gimple_bb (phi); | |
1640 | ||
1641 | if (is_non_loop_exit_postdominating (use_bb, phi_bb)) | |
1642 | return false; | |
1643 | ||
1644 | has_valid_preds = find_predicates (&preds, &num_preds, | |
1645 | phi_bb, use_bb); | |
1646 | ||
1647 | if (!has_valid_preds) | |
1648 | { | |
1649 | destroy_predicate_vecs (num_preds, preds); | |
1650 | return false; | |
1651 | } | |
1652 | ||
1653 | if (dump_file) | |
1654 | dump_predicates (use_stmt, num_preds, preds, | |
e74780a3 | 1655 | "\nUse in stmt "); |
34f97b94 XDL |
1656 | |
1657 | has_valid_preds = find_def_preds (&def_preds, | |
1658 | &num_def_preds, phi); | |
1659 | ||
1660 | if (has_valid_preds) | |
1661 | { | |
1662 | if (dump_file) | |
1663 | dump_predicates (phi, num_def_preds, def_preds, | |
1664 | "Operand defs of phi "); | |
1665 | is_properly_guarded = | |
1666 | is_superset_of (def_preds, num_def_preds, | |
1667 | preds, num_preds); | |
1668 | } | |
1669 | ||
1670 | /* further prune the dead incoming phi edges. */ | |
1671 | if (!is_properly_guarded) | |
1672 | is_properly_guarded | |
1673 | = use_pred_not_overlap_with_undef_path_pred ( | |
1674 | num_preds, preds, phi, uninit_opnds, visited_phis); | |
1675 | ||
1676 | destroy_predicate_vecs (num_preds, preds); | |
1677 | destroy_predicate_vecs (num_def_preds, def_preds); | |
1678 | return is_properly_guarded; | |
1679 | } | |
1680 | ||
1681 | /* Searches through all uses of a potentially | |
1682 | uninitialized variable defined by PHI and returns a use | |
1683 | statement if the use is not properly guarded. It returns | |
1684 | NULL if all uses are guarded. UNINIT_OPNDS is a bitvector | |
1685 | holding the position(s) of uninit PHI operands. WORKLIST | |
1686 | is the vector of candidate phis that may be updated by this | |
1687 | function. ADDED_TO_WORKLIST is the pointer set tracking | |
1688 | if the new phi is already in the worklist. */ | |
1689 | ||
1690 | static gimple | |
1691 | find_uninit_use (gimple phi, unsigned uninit_opnds, | |
1692 | VEC(gimple, heap) **worklist, | |
1693 | struct pointer_set_t *added_to_worklist) | |
1694 | { | |
1695 | tree phi_result; | |
1696 | use_operand_p use_p; | |
1697 | gimple use_stmt; | |
1698 | imm_use_iterator iter; | |
1699 | ||
1700 | phi_result = gimple_phi_result (phi); | |
1701 | ||
1702 | FOR_EACH_IMM_USE_FAST (use_p, iter, phi_result) | |
1703 | { | |
1704 | struct pointer_set_t *visited_phis; | |
1705 | basic_block use_bb; | |
1706 | ||
480161b5 RG |
1707 | use_stmt = USE_STMT (use_p); |
1708 | if (is_gimple_debug (use_stmt)) | |
1709 | continue; | |
34f97b94 XDL |
1710 | |
1711 | visited_phis = pointer_set_create (); | |
1712 | ||
34f97b94 | 1713 | if (gimple_code (use_stmt) == GIMPLE_PHI) |
480161b5 RG |
1714 | use_bb = gimple_phi_arg_edge (use_stmt, |
1715 | PHI_ARG_INDEX_FROM_USE (use_p))->src; | |
1716 | else | |
1717 | use_bb = gimple_bb (use_stmt); | |
34f97b94 XDL |
1718 | |
1719 | if (is_use_properly_guarded (use_stmt, | |
1720 | use_bb, | |
1721 | phi, | |
1722 | uninit_opnds, | |
1723 | visited_phis)) | |
1724 | { | |
1725 | pointer_set_destroy (visited_phis); | |
1726 | continue; | |
1727 | } | |
1728 | pointer_set_destroy (visited_phis); | |
1729 | ||
e74780a3 XDL |
1730 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1731 | { | |
1732 | fprintf (dump_file, "[CHECK]: Found unguarded use: "); | |
1733 | print_gimple_stmt (dump_file, use_stmt, 0, 0); | |
1734 | } | |
34f97b94 XDL |
1735 | /* Found one real use, return. */ |
1736 | if (gimple_code (use_stmt) != GIMPLE_PHI) | |
e74780a3 | 1737 | return use_stmt; |
34f97b94 XDL |
1738 | |
1739 | /* Found a phi use that is not guarded, | |
1740 | add the phi to the worklist. */ | |
1741 | if (!pointer_set_insert (added_to_worklist, | |
1742 | use_stmt)) | |
1743 | { | |
e74780a3 XDL |
1744 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1745 | { | |
1746 | fprintf (dump_file, "[WORKLIST]: Update worklist with phi: "); | |
1747 | print_gimple_stmt (dump_file, use_stmt, 0, 0); | |
1748 | } | |
1749 | ||
34f97b94 XDL |
1750 | VEC_safe_push (gimple, heap, *worklist, use_stmt); |
1751 | pointer_set_insert (possibly_undefined_names, | |
1752 | phi_result); | |
1753 | } | |
1754 | } | |
1755 | ||
1756 | return NULL; | |
1757 | } | |
1758 | ||
1759 | /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions | |
1760 | and gives warning if there exists a runtime path from the entry to a | |
1761 | use of the PHI def that does not contain a definition. In other words, | |
1762 | the warning is on the real use. The more dead paths that can be pruned | |
1763 | by the compiler, the fewer false positives the warning is. WORKLIST | |
1764 | is a vector of candidate phis to be examined. ADDED_TO_WORKLIST is | |
1765 | a pointer set tracking if the new phi is added to the worklist or not. */ | |
1766 | ||
1767 | static void | |
1768 | warn_uninitialized_phi (gimple phi, VEC(gimple, heap) **worklist, | |
1769 | struct pointer_set_t *added_to_worklist) | |
1770 | { | |
1771 | unsigned uninit_opnds; | |
1772 | gimple uninit_use_stmt = 0; | |
1773 | tree uninit_op; | |
1774 | ||
1775 | /* Don't look at memory tags. */ | |
1776 | if (!is_gimple_reg (gimple_phi_result (phi))) | |
1777 | return; | |
1778 | ||
1779 | uninit_opnds = compute_uninit_opnds_pos (phi); | |
1780 | ||
1781 | if (MASK_EMPTY (uninit_opnds)) | |
1782 | return; | |
1783 | ||
e74780a3 XDL |
1784 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1785 | { | |
1786 | fprintf (dump_file, "[CHECK]: examining phi: "); | |
1787 | print_gimple_stmt (dump_file, phi, 0, 0); | |
1788 | } | |
1789 | ||
34f97b94 XDL |
1790 | /* Now check if we have any use of the value without proper guard. */ |
1791 | uninit_use_stmt = find_uninit_use (phi, uninit_opnds, | |
1792 | worklist, added_to_worklist); | |
1793 | ||
1794 | /* All uses are properly guarded. */ | |
1795 | if (!uninit_use_stmt) | |
1796 | return; | |
1797 | ||
1798 | uninit_op = gimple_phi_arg_def (phi, MASK_FIRST_SET_BIT (uninit_opnds)); | |
1799 | warn_uninit (uninit_op, | |
1800 | "%qD may be used uninitialized in this function", | |
1801 | uninit_use_stmt); | |
1802 | ||
1803 | } | |
1804 | ||
1805 | ||
1806 | /* Entry point to the late uninitialized warning pass. */ | |
1807 | ||
1808 | static unsigned int | |
1809 | execute_late_warn_uninitialized (void) | |
1810 | { | |
1811 | basic_block bb; | |
1812 | gimple_stmt_iterator gsi; | |
1813 | VEC(gimple, heap) *worklist = 0; | |
1814 | struct pointer_set_t *added_to_worklist; | |
1815 | ||
1816 | calculate_dominance_info (CDI_DOMINATORS); | |
1817 | calculate_dominance_info (CDI_POST_DOMINATORS); | |
1818 | /* Re-do the plain uninitialized variable check, as optimization may have | |
1819 | straightened control flow. Do this first so that we don't accidentally | |
1820 | get a "may be" warning when we'd have seen an "is" warning later. */ | |
1821 | warn_uninitialized_vars (/*warn_possibly_uninitialized=*/1); | |
1822 | ||
1823 | timevar_push (TV_TREE_UNINIT); | |
1824 | ||
1825 | possibly_undefined_names = pointer_set_create (); | |
1826 | added_to_worklist = pointer_set_create (); | |
1827 | ||
1828 | /* Initialize worklist */ | |
1829 | FOR_EACH_BB (bb) | |
1830 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
1831 | { | |
1832 | gimple phi = gsi_stmt (gsi); | |
1833 | size_t n, i; | |
1834 | ||
1835 | n = gimple_phi_num_args (phi); | |
1836 | ||
1837 | /* Don't look at memory tags. */ | |
1838 | if (!is_gimple_reg (gimple_phi_result (phi))) | |
1839 | continue; | |
1840 | ||
1841 | for (i = 0; i < n; ++i) | |
1842 | { | |
1843 | tree op = gimple_phi_arg_def (phi, i); | |
1844 | if (TREE_CODE (op) == SSA_NAME | |
1845 | && ssa_undefined_value_p (op)) | |
1846 | { | |
1847 | VEC_safe_push (gimple, heap, worklist, phi); | |
1848 | pointer_set_insert (added_to_worklist, phi); | |
e74780a3 XDL |
1849 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1850 | { | |
1851 | fprintf (dump_file, "[WORKLIST]: add to initial list: "); | |
1852 | print_gimple_stmt (dump_file, phi, 0, 0); | |
1853 | } | |
34f97b94 XDL |
1854 | break; |
1855 | } | |
1856 | } | |
1857 | } | |
1858 | ||
1859 | while (VEC_length (gimple, worklist) != 0) | |
1860 | { | |
1861 | gimple cur_phi = 0; | |
1862 | cur_phi = VEC_pop (gimple, worklist); | |
1863 | warn_uninitialized_phi (cur_phi, &worklist, added_to_worklist); | |
1864 | } | |
e74780a3 | 1865 | |
34f97b94 XDL |
1866 | VEC_free (gimple, heap, worklist); |
1867 | pointer_set_destroy (added_to_worklist); | |
1868 | pointer_set_destroy (possibly_undefined_names); | |
1869 | possibly_undefined_names = NULL; | |
1870 | free_dominance_info (CDI_POST_DOMINATORS); | |
1871 | timevar_pop (TV_TREE_UNINIT); | |
1872 | return 0; | |
1873 | } | |
1874 | ||
1875 | static bool | |
1876 | gate_warn_uninitialized (void) | |
1877 | { | |
1878 | return warn_uninitialized != 0; | |
1879 | } | |
1880 | ||
1881 | struct gimple_opt_pass pass_late_warn_uninitialized = | |
1882 | { | |
1883 | { | |
1884 | GIMPLE_PASS, | |
1885 | "uninit", /* name */ | |
1886 | gate_warn_uninitialized, /* gate */ | |
1887 | execute_late_warn_uninitialized, /* execute */ | |
1888 | NULL, /* sub */ | |
1889 | NULL, /* next */ | |
1890 | 0, /* static_pass_number */ | |
1891 | TV_NONE, /* tv_id */ | |
1892 | PROP_ssa, /* properties_required */ | |
1893 | 0, /* properties_provided */ | |
1894 | 0, /* properties_destroyed */ | |
1895 | 0, /* todo_flags_start */ | |
1896 | 0 /* todo_flags_finish */ | |
1897 | } | |
1898 | }; |