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34f97b94 | 1 | /* Predicate aware uninitialized variable warning. |
5624e564 | 2 | Copyright (C) 2001-2015 Free Software Foundation, Inc. |
34f97b94 XDL |
3 | Contributed by Xinliang David Li <davidxl@google.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 3, 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 COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
c7131fb2 | 24 | #include "backend.h" |
34f97b94 | 25 | #include "tree.h" |
c7131fb2 AM |
26 | #include "gimple.h" |
27 | #include "hard-reg-set.h" | |
28 | #include "ssa.h" | |
29 | #include "alias.h" | |
40e23961 | 30 | #include "fold-const.h" |
34f97b94 | 31 | #include "flags.h" |
34f97b94 | 32 | #include "tm_p.h" |
cf835838 | 33 | #include "gimple-pretty-print.h" |
2fb9a547 | 34 | #include "internal-fn.h" |
5be5c238 | 35 | #include "gimple-iterator.h" |
442b4905 | 36 | #include "tree-ssa.h" |
34f97b94 | 37 | #include "tree-inline.h" |
34f97b94 | 38 | #include "tree-pass.h" |
718f9c0f | 39 | #include "diagnostic-core.h" |
92261ce0 | 40 | #include "params.h" |
666e8e06 | 41 | #include "tree-cfg.h" |
34f97b94 XDL |
42 | |
43 | /* This implements the pass that does predicate aware warning on uses of | |
44 | possibly uninitialized variables. The pass first collects the set of | |
45 | possibly uninitialized SSA names. For each such name, it walks through | |
46 | all its immediate uses. For each immediate use, it rebuilds the condition | |
47 | expression (the predicate) that guards the use. The predicate is then | |
48 | examined to see if the variable is always defined under that same condition. | |
49 | This is done either by pruning the unrealizable paths that lead to the | |
50 | default definitions or by checking if the predicate set that guards the | |
51 | defining paths is a superset of the use predicate. */ | |
52 | ||
53 | ||
54 | /* Pointer set of potentially undefined ssa names, i.e., | |
55 | ssa names that are defined by phi with operands that | |
56 | are not defined or potentially undefined. */ | |
6e2830c3 | 57 | static hash_set<tree> *possibly_undefined_names = 0; |
34f97b94 XDL |
58 | |
59 | /* Bit mask handling macros. */ | |
60 | #define MASK_SET_BIT(mask, pos) mask |= (1 << pos) | |
61 | #define MASK_TEST_BIT(mask, pos) (mask & (1 << pos)) | |
62 | #define MASK_EMPTY(mask) (mask == 0) | |
63 | ||
64 | /* Returns the first bit position (starting from LSB) | |
65 | in mask that is non zero. Returns -1 if the mask is empty. */ | |
66 | static int | |
67 | get_mask_first_set_bit (unsigned mask) | |
68 | { | |
69 | int pos = 0; | |
70 | if (mask == 0) | |
71 | return -1; | |
72 | ||
73 | while ((mask & (1 << pos)) == 0) | |
74 | pos++; | |
75 | ||
76 | return pos; | |
77 | } | |
78 | #define MASK_FIRST_SET_BIT(mask) get_mask_first_set_bit (mask) | |
79 | ||
34f97b94 | 80 | /* Return true if T, an SSA_NAME, has an undefined value. */ |
c152901f AM |
81 | static bool |
82 | has_undefined_value_p (tree t) | |
34f97b94 | 83 | { |
c152901f | 84 | return (ssa_undefined_value_p (t) |
34f97b94 | 85 | || (possibly_undefined_names |
6e2830c3 | 86 | && possibly_undefined_names->contains (t))); |
34f97b94 XDL |
87 | } |
88 | ||
c152901f AM |
89 | |
90 | ||
91 | /* Like has_undefined_value_p, but don't return true if TREE_NO_WARNING | |
ba7e83f8 JJ |
92 | is set on SSA_NAME_VAR. */ |
93 | ||
94 | static inline bool | |
c152901f AM |
95 | uninit_undefined_value_p (tree t) { |
96 | if (!has_undefined_value_p (t)) | |
ba7e83f8 JJ |
97 | return false; |
98 | if (SSA_NAME_VAR (t) && TREE_NO_WARNING (SSA_NAME_VAR (t))) | |
99 | return false; | |
100 | return true; | |
101 | } | |
102 | ||
c152901f AM |
103 | /* Emit warnings for uninitialized variables. This is done in two passes. |
104 | ||
105 | The first pass notices real uses of SSA names with undefined values. | |
106 | Such uses are unconditionally uninitialized, and we can be certain that | |
107 | such a use is a mistake. This pass is run before most optimizations, | |
108 | so that we catch as many as we can. | |
109 | ||
110 | The second pass follows PHI nodes to find uses that are potentially | |
111 | uninitialized. In this case we can't necessarily prove that the use | |
112 | is really uninitialized. This pass is run after most optimizations, | |
113 | so that we thread as many jumps and possible, and delete as much dead | |
114 | code as possible, in order to reduce false positives. We also look | |
115 | again for plain uninitialized variables, since optimization may have | |
116 | changed conditionally uninitialized to unconditionally uninitialized. */ | |
117 | ||
118 | /* Emit a warning for EXPR based on variable VAR at the point in the | |
119 | program T, an SSA_NAME, is used being uninitialized. The exact | |
e1ec47c4 TP |
120 | warning text is in MSGID and DATA is the gimple stmt with info about |
121 | the location in source code. When DATA is a GIMPLE_PHI, PHIARG_IDX | |
122 | gives which argument of the phi node to take the location from. WC | |
123 | is the warning code. */ | |
c152901f AM |
124 | |
125 | static void | |
e1ec47c4 TP |
126 | warn_uninit (enum opt_code wc, tree t, tree expr, tree var, |
127 | const char *gmsgid, void *data, location_t phiarg_loc) | |
c152901f AM |
128 | { |
129 | gimple context = (gimple) data; | |
130 | location_t location, cfun_loc; | |
131 | expanded_location xloc, floc; | |
132 | ||
e1ec47c4 TP |
133 | /* Ignore COMPLEX_EXPR as initializing only a part of a complex |
134 | turns in a COMPLEX_EXPR with the not initialized part being | |
135 | set to its previous (undefined) value. */ | |
136 | if (is_gimple_assign (context) | |
137 | && gimple_assign_rhs_code (context) == COMPLEX_EXPR) | |
138 | return; | |
c152901f AM |
139 | if (!has_undefined_value_p (t)) |
140 | return; | |
141 | ||
142 | /* TREE_NO_WARNING either means we already warned, or the front end | |
143 | wishes to suppress the warning. */ | |
144 | if ((context | |
145 | && (gimple_no_warning_p (context) | |
146 | || (gimple_assign_single_p (context) | |
147 | && TREE_NO_WARNING (gimple_assign_rhs1 (context))))) | |
148 | || TREE_NO_WARNING (expr)) | |
149 | return; | |
150 | ||
e1ec47c4 TP |
151 | if (context != NULL && gimple_has_location (context)) |
152 | location = gimple_location (context); | |
153 | else if (phiarg_loc != UNKNOWN_LOCATION) | |
154 | location = phiarg_loc; | |
155 | else | |
156 | location = DECL_SOURCE_LOCATION (var); | |
c152901f AM |
157 | location = linemap_resolve_location (line_table, location, |
158 | LRK_SPELLING_LOCATION, | |
159 | NULL); | |
160 | cfun_loc = DECL_SOURCE_LOCATION (cfun->decl); | |
161 | xloc = expand_location (location); | |
162 | floc = expand_location (cfun_loc); | |
163 | if (warning_at (location, wc, gmsgid, expr)) | |
164 | { | |
165 | TREE_NO_WARNING (expr) = 1; | |
166 | ||
167 | if (location == DECL_SOURCE_LOCATION (var)) | |
168 | return; | |
169 | if (xloc.file != floc.file | |
170 | || linemap_location_before_p (line_table, | |
171 | location, cfun_loc) | |
172 | || linemap_location_before_p (line_table, | |
173 | cfun->function_end_locus, | |
174 | location)) | |
175 | inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var); | |
176 | } | |
177 | } | |
178 | ||
179 | static unsigned int | |
180 | warn_uninitialized_vars (bool warn_possibly_uninitialized) | |
181 | { | |
182 | gimple_stmt_iterator gsi; | |
183 | basic_block bb; | |
184 | ||
11cd3bed | 185 | FOR_EACH_BB_FN (bb, cfun) |
c152901f AM |
186 | { |
187 | bool always_executed = dominated_by_p (CDI_POST_DOMINATORS, | |
fefa31b5 | 188 | single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)), bb); |
c152901f AM |
189 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
190 | { | |
191 | gimple stmt = gsi_stmt (gsi); | |
192 | use_operand_p use_p; | |
193 | ssa_op_iter op_iter; | |
194 | tree use; | |
195 | ||
196 | if (is_gimple_debug (stmt)) | |
197 | continue; | |
198 | ||
199 | /* We only do data flow with SSA_NAMEs, so that's all we | |
200 | can warn about. */ | |
201 | FOR_EACH_SSA_USE_OPERAND (use_p, stmt, op_iter, SSA_OP_USE) | |
202 | { | |
203 | use = USE_FROM_PTR (use_p); | |
204 | if (always_executed) | |
205 | warn_uninit (OPT_Wuninitialized, use, | |
206 | SSA_NAME_VAR (use), SSA_NAME_VAR (use), | |
207 | "%qD is used uninitialized in this function", | |
e1ec47c4 | 208 | stmt, UNKNOWN_LOCATION); |
c152901f AM |
209 | else if (warn_possibly_uninitialized) |
210 | warn_uninit (OPT_Wmaybe_uninitialized, use, | |
211 | SSA_NAME_VAR (use), SSA_NAME_VAR (use), | |
212 | "%qD may be used uninitialized in this function", | |
e1ec47c4 | 213 | stmt, UNKNOWN_LOCATION); |
c152901f AM |
214 | } |
215 | ||
216 | /* For memory the only cheap thing we can do is see if we | |
217 | have a use of the default def of the virtual operand. | |
c152901f AM |
218 | ??? Not so cheap would be to use the alias oracle via |
219 | walk_aliased_vdefs, if we don't find any aliasing vdef | |
220 | warn as is-used-uninitialized, if we don't find an aliasing | |
221 | vdef that kills our use (stmt_kills_ref_p), warn as | |
222 | may-be-used-uninitialized. But this walk is quadratic and | |
223 | so must be limited which means we would miss warning | |
224 | opportunities. */ | |
225 | use = gimple_vuse (stmt); | |
226 | if (use | |
227 | && gimple_assign_single_p (stmt) | |
228 | && !gimple_vdef (stmt) | |
229 | && SSA_NAME_IS_DEFAULT_DEF (use)) | |
230 | { | |
231 | tree rhs = gimple_assign_rhs1 (stmt); | |
232 | tree base = get_base_address (rhs); | |
233 | ||
234 | /* Do not warn if it can be initialized outside this function. */ | |
235 | if (TREE_CODE (base) != VAR_DECL | |
236 | || DECL_HARD_REGISTER (base) | |
237 | || is_global_var (base)) | |
238 | continue; | |
239 | ||
240 | if (always_executed) | |
927734cf | 241 | warn_uninit (OPT_Wuninitialized, use, |
c152901f AM |
242 | gimple_assign_rhs1 (stmt), base, |
243 | "%qE is used uninitialized in this function", | |
e1ec47c4 | 244 | stmt, UNKNOWN_LOCATION); |
c152901f AM |
245 | else if (warn_possibly_uninitialized) |
246 | warn_uninit (OPT_Wmaybe_uninitialized, use, | |
247 | gimple_assign_rhs1 (stmt), base, | |
248 | "%qE may be used uninitialized in this function", | |
e1ec47c4 | 249 | stmt, UNKNOWN_LOCATION); |
c152901f AM |
250 | } |
251 | } | |
252 | } | |
253 | ||
254 | return 0; | |
255 | } | |
256 | ||
927734cf XDL |
257 | /* Checks if the operand OPND of PHI is defined by |
258 | another phi with one operand defined by this PHI, | |
259 | but the rest operands are all defined. If yes, | |
026c3cfd | 260 | returns true to skip this operand as being |
34f97b94 XDL |
261 | redundant. Can be enhanced to be more general. */ |
262 | ||
263 | static bool | |
264 | can_skip_redundant_opnd (tree opnd, gimple phi) | |
265 | { | |
266 | gimple op_def; | |
267 | tree phi_def; | |
268 | int i, n; | |
269 | ||
270 | phi_def = gimple_phi_result (phi); | |
271 | op_def = SSA_NAME_DEF_STMT (opnd); | |
272 | if (gimple_code (op_def) != GIMPLE_PHI) | |
273 | return false; | |
274 | n = gimple_phi_num_args (op_def); | |
275 | for (i = 0; i < n; ++i) | |
276 | { | |
277 | tree op = gimple_phi_arg_def (op_def, i); | |
278 | if (TREE_CODE (op) != SSA_NAME) | |
279 | continue; | |
ba7e83f8 | 280 | if (op != phi_def && uninit_undefined_value_p (op)) |
34f97b94 XDL |
281 | return false; |
282 | } | |
283 | ||
284 | return true; | |
285 | } | |
286 | ||
287 | /* Returns a bit mask holding the positions of arguments in PHI | |
288 | that have empty (or possibly empty) definitions. */ | |
289 | ||
290 | static unsigned | |
538dd0b7 | 291 | compute_uninit_opnds_pos (gphi *phi) |
34f97b94 XDL |
292 | { |
293 | size_t i, n; | |
294 | unsigned uninit_opnds = 0; | |
295 | ||
296 | n = gimple_phi_num_args (phi); | |
98d30e4f XDL |
297 | /* Bail out for phi with too many args. */ |
298 | if (n > 32) | |
299 | return 0; | |
34f97b94 XDL |
300 | |
301 | for (i = 0; i < n; ++i) | |
302 | { | |
303 | tree op = gimple_phi_arg_def (phi, i); | |
304 | if (TREE_CODE (op) == SSA_NAME | |
ba7e83f8 | 305 | && uninit_undefined_value_p (op) |
34f97b94 | 306 | && !can_skip_redundant_opnd (op, phi)) |
e7d764f3 | 307 | { |
e7d764f3 JJ |
308 | if (cfun->has_nonlocal_label || cfun->calls_setjmp) |
309 | { | |
aea0101d RB |
310 | /* Ignore SSA_NAMEs that appear on abnormal edges |
311 | somewhere. */ | |
312 | if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) | |
313 | continue; | |
e7d764f3 JJ |
314 | } |
315 | MASK_SET_BIT (uninit_opnds, i); | |
316 | } | |
34f97b94 XDL |
317 | } |
318 | return uninit_opnds; | |
319 | } | |
320 | ||
321 | /* Find the immediate postdominator PDOM of the specified | |
322 | basic block BLOCK. */ | |
323 | ||
324 | static inline basic_block | |
325 | find_pdom (basic_block block) | |
326 | { | |
fefa31b5 DM |
327 | if (block == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
328 | return EXIT_BLOCK_PTR_FOR_FN (cfun); | |
34f97b94 XDL |
329 | else |
330 | { | |
331 | basic_block bb | |
332 | = get_immediate_dominator (CDI_POST_DOMINATORS, block); | |
333 | if (! bb) | |
fefa31b5 | 334 | return EXIT_BLOCK_PTR_FOR_FN (cfun); |
34f97b94 XDL |
335 | return bb; |
336 | } | |
337 | } | |
338 | ||
339 | /* Find the immediate DOM of the specified | |
340 | basic block BLOCK. */ | |
341 | ||
342 | static inline basic_block | |
343 | find_dom (basic_block block) | |
344 | { | |
fefa31b5 DM |
345 | if (block == ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
346 | return ENTRY_BLOCK_PTR_FOR_FN (cfun); | |
34f97b94 XDL |
347 | else |
348 | { | |
349 | basic_block bb = get_immediate_dominator (CDI_DOMINATORS, block); | |
350 | if (! bb) | |
fefa31b5 | 351 | return ENTRY_BLOCK_PTR_FOR_FN (cfun); |
34f97b94 XDL |
352 | return bb; |
353 | } | |
354 | } | |
355 | ||
356 | /* Returns true if BB1 is postdominating BB2 and BB1 is | |
357 | not a loop exit bb. The loop exit bb check is simple and does | |
358 | not cover all cases. */ | |
359 | ||
360 | static bool | |
361 | is_non_loop_exit_postdominating (basic_block bb1, basic_block bb2) | |
362 | { | |
363 | if (!dominated_by_p (CDI_POST_DOMINATORS, bb2, bb1)) | |
364 | return false; | |
365 | ||
366 | if (single_pred_p (bb1) && !single_succ_p (bb2)) | |
367 | return false; | |
368 | ||
369 | return true; | |
370 | } | |
371 | ||
372 | /* Find the closest postdominator of a specified BB, which is control | |
373 | equivalent to BB. */ | |
374 | ||
375 | static inline basic_block | |
376 | find_control_equiv_block (basic_block bb) | |
377 | { | |
378 | basic_block pdom; | |
379 | ||
380 | pdom = find_pdom (bb); | |
381 | ||
382 | /* Skip the postdominating bb that is also loop exit. */ | |
383 | if (!is_non_loop_exit_postdominating (pdom, bb)) | |
384 | return NULL; | |
385 | ||
386 | if (dominated_by_p (CDI_DOMINATORS, pdom, bb)) | |
387 | return pdom; | |
388 | ||
389 | return NULL; | |
390 | } | |
391 | ||
392 | #define MAX_NUM_CHAINS 8 | |
393 | #define MAX_CHAIN_LEN 5 | |
4dc1d68c | 394 | #define MAX_POSTDOM_CHECK 8 |
666e8e06 | 395 | #define MAX_SWITCH_CASES 40 |
34f97b94 XDL |
396 | |
397 | /* Computes the control dependence chains (paths of edges) | |
398 | for DEP_BB up to the dominating basic block BB (the head node of a | |
92261ce0 JJ |
399 | chain should be dominated by it). CD_CHAINS is pointer to an |
400 | array holding the result chains. CUR_CD_CHAIN is the current | |
34f97b94 XDL |
401 | chain being computed. *NUM_CHAINS is total number of chains. The |
402 | function returns true if the information is successfully computed, | |
403 | return false if there is no control dependence or not computed. */ | |
404 | ||
405 | static bool | |
406 | compute_control_dep_chain (basic_block bb, basic_block dep_bb, | |
9771b263 | 407 | vec<edge> *cd_chains, |
34f97b94 | 408 | size_t *num_chains, |
92261ce0 JJ |
409 | vec<edge> *cur_cd_chain, |
410 | int *num_calls) | |
34f97b94 XDL |
411 | { |
412 | edge_iterator ei; | |
413 | edge e; | |
414 | size_t i; | |
415 | bool found_cd_chain = false; | |
416 | size_t cur_chain_len = 0; | |
417 | ||
418 | if (EDGE_COUNT (bb->succs) < 2) | |
419 | return false; | |
420 | ||
92261ce0 JJ |
421 | if (*num_calls > PARAM_VALUE (PARAM_UNINIT_CONTROL_DEP_ATTEMPTS)) |
422 | return false; | |
423 | ++*num_calls; | |
424 | ||
927734cf | 425 | /* Could use a set instead. */ |
9771b263 | 426 | cur_chain_len = cur_cd_chain->length (); |
34f97b94 XDL |
427 | if (cur_chain_len > MAX_CHAIN_LEN) |
428 | return false; | |
429 | ||
430 | for (i = 0; i < cur_chain_len; i++) | |
431 | { | |
9771b263 | 432 | edge e = (*cur_cd_chain)[i]; |
927734cf | 433 | /* Cycle detected. */ |
34f97b94 XDL |
434 | if (e->src == bb) |
435 | return false; | |
436 | } | |
437 | ||
438 | FOR_EACH_EDGE (e, ei, bb->succs) | |
439 | { | |
440 | basic_block cd_bb; | |
4dc1d68c | 441 | int post_dom_check = 0; |
34f97b94 XDL |
442 | if (e->flags & (EDGE_FAKE | EDGE_ABNORMAL)) |
443 | continue; | |
444 | ||
445 | cd_bb = e->dest; | |
9771b263 | 446 | cur_cd_chain->safe_push (e); |
34f97b94 XDL |
447 | while (!is_non_loop_exit_postdominating (cd_bb, bb)) |
448 | { | |
449 | if (cd_bb == dep_bb) | |
450 | { | |
451 | /* Found a direct control dependence. */ | |
452 | if (*num_chains < MAX_NUM_CHAINS) | |
453 | { | |
9771b263 | 454 | cd_chains[*num_chains] = cur_cd_chain->copy (); |
34f97b94 XDL |
455 | (*num_chains)++; |
456 | } | |
457 | found_cd_chain = true; | |
927734cf | 458 | /* Check path from next edge. */ |
34f97b94 XDL |
459 | break; |
460 | } | |
461 | ||
462 | /* Now check if DEP_BB is indirectly control dependent on BB. */ | |
463 | if (compute_control_dep_chain (cd_bb, dep_bb, cd_chains, | |
92261ce0 | 464 | num_chains, cur_cd_chain, num_calls)) |
34f97b94 XDL |
465 | { |
466 | found_cd_chain = true; | |
467 | break; | |
468 | } | |
469 | ||
470 | cd_bb = find_pdom (cd_bb); | |
4dc1d68c | 471 | post_dom_check++; |
fefa31b5 DM |
472 | if (cd_bb == EXIT_BLOCK_PTR_FOR_FN (cfun) || post_dom_check > |
473 | MAX_POSTDOM_CHECK) | |
34f97b94 XDL |
474 | break; |
475 | } | |
9771b263 DN |
476 | cur_cd_chain->pop (); |
477 | gcc_assert (cur_cd_chain->length () == cur_chain_len); | |
34f97b94 | 478 | } |
9771b263 | 479 | gcc_assert (cur_cd_chain->length () == cur_chain_len); |
34f97b94 XDL |
480 | |
481 | return found_cd_chain; | |
482 | } | |
483 | ||
927734cf XDL |
484 | /* The type to represent a simple predicate */ |
485 | ||
a79683d5 | 486 | struct pred_info |
34f97b94 | 487 | { |
927734cf XDL |
488 | tree pred_lhs; |
489 | tree pred_rhs; | |
490 | enum tree_code cond_code; | |
34f97b94 | 491 | bool invert; |
a79683d5 | 492 | }; |
927734cf XDL |
493 | |
494 | /* The type to represent a sequence of predicates grouped | |
495 | with .AND. operation. */ | |
34f97b94 | 496 | |
927734cf | 497 | typedef vec<pred_info, va_heap, vl_ptr> pred_chain; |
34f97b94 | 498 | |
927734cf XDL |
499 | /* The type to represent a sequence of pred_chains grouped |
500 | with .OR. operation. */ | |
501 | ||
502 | typedef vec<pred_chain, va_heap, vl_ptr> pred_chain_union; | |
34f97b94 XDL |
503 | |
504 | /* Converts the chains of control dependence edges into a set of | |
505 | predicates. A control dependence chain is represented by a vector | |
506 | edges. DEP_CHAINS points to an array of dependence chains. | |
507 | NUM_CHAINS is the size of the chain array. One edge in a dependence | |
927734cf | 508 | chain is mapped to predicate expression represented by pred_info |
34f97b94 | 509 | type. One dependence chain is converted to a composite predicate that |
927734cf XDL |
510 | is the result of AND operation of pred_info mapped to each edge. |
511 | A composite predicate is presented by a vector of pred_info. On | |
34f97b94 XDL |
512 | return, *PREDS points to the resulting array of composite predicates. |
513 | *NUM_PREDS is the number of composite predictes. */ | |
514 | ||
515 | static bool | |
9771b263 | 516 | convert_control_dep_chain_into_preds (vec<edge> *dep_chains, |
34f97b94 | 517 | size_t num_chains, |
927734cf | 518 | pred_chain_union *preds) |
34f97b94 XDL |
519 | { |
520 | bool has_valid_pred = false; | |
521 | size_t i, j; | |
522 | if (num_chains == 0 || num_chains >= MAX_NUM_CHAINS) | |
523 | return false; | |
524 | ||
34f97b94 XDL |
525 | /* Now convert the control dep chain into a set |
526 | of predicates. */ | |
927734cf | 527 | preds->reserve (num_chains); |
34f97b94 XDL |
528 | |
529 | for (i = 0; i < num_chains; i++) | |
530 | { | |
9771b263 | 531 | vec<edge> one_cd_chain = dep_chains[i]; |
c375a3a4 DL |
532 | |
533 | has_valid_pred = false; | |
927734cf | 534 | pred_chain t_chain = vNULL; |
9771b263 | 535 | for (j = 0; j < one_cd_chain.length (); j++) |
34f97b94 XDL |
536 | { |
537 | gimple cond_stmt; | |
538 | gimple_stmt_iterator gsi; | |
539 | basic_block guard_bb; | |
927734cf | 540 | pred_info one_pred; |
34f97b94 XDL |
541 | edge e; |
542 | ||
9771b263 | 543 | e = one_cd_chain[j]; |
34f97b94 XDL |
544 | guard_bb = e->src; |
545 | gsi = gsi_last_bb (guard_bb); | |
546 | if (gsi_end_p (gsi)) | |
547 | { | |
548 | has_valid_pred = false; | |
549 | break; | |
550 | } | |
551 | cond_stmt = gsi_stmt (gsi); | |
927734cf | 552 | if (is_gimple_call (cond_stmt) |
34f97b94 XDL |
553 | && EDGE_COUNT (e->src->succs) >= 2) |
554 | { | |
555 | /* Ignore EH edge. Can add assertion | |
556 | on the other edge's flag. */ | |
557 | continue; | |
558 | } | |
559 | /* Skip if there is essentially one succesor. */ | |
560 | if (EDGE_COUNT (e->src->succs) == 2) | |
561 | { | |
562 | edge e1; | |
563 | edge_iterator ei1; | |
564 | bool skip = false; | |
565 | ||
566 | FOR_EACH_EDGE (e1, ei1, e->src->succs) | |
567 | { | |
568 | if (EDGE_COUNT (e1->dest->succs) == 0) | |
569 | { | |
570 | skip = true; | |
571 | break; | |
572 | } | |
573 | } | |
574 | if (skip) | |
575 | continue; | |
576 | } | |
666e8e06 RB |
577 | if (gimple_code (cond_stmt) == GIMPLE_COND) |
578 | { | |
579 | one_pred.pred_lhs = gimple_cond_lhs (cond_stmt); | |
580 | one_pred.pred_rhs = gimple_cond_rhs (cond_stmt); | |
581 | one_pred.cond_code = gimple_cond_code (cond_stmt); | |
582 | one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE); | |
583 | t_chain.safe_push (one_pred); | |
584 | has_valid_pred = true; | |
585 | } | |
586 | else if (gswitch *gs = dyn_cast <gswitch *> (cond_stmt)) | |
587 | { | |
588 | /* Avoid quadratic behavior. */ | |
589 | if (gimple_switch_num_labels (gs) > MAX_SWITCH_CASES) | |
590 | { | |
591 | has_valid_pred = false; | |
592 | break; | |
593 | } | |
594 | /* Find the case label. */ | |
595 | tree l = NULL_TREE; | |
596 | unsigned idx; | |
597 | for (idx = 0; idx < gimple_switch_num_labels (gs); ++idx) | |
598 | { | |
599 | tree tl = gimple_switch_label (gs, idx); | |
600 | if (e->dest == label_to_block (CASE_LABEL (tl))) | |
601 | { | |
602 | if (!l) | |
603 | l = tl; | |
604 | else | |
605 | { | |
606 | l = NULL_TREE; | |
607 | break; | |
608 | } | |
609 | } | |
610 | } | |
611 | /* If more than one label reaches this block or the case | |
612 | label doesn't have a single value (like the default one) | |
613 | fail. */ | |
614 | if (!l | |
615 | || !CASE_LOW (l) | |
616 | || (CASE_HIGH (l) && !operand_equal_p (CASE_LOW (l), | |
617 | CASE_HIGH (l), 0))) | |
618 | { | |
619 | has_valid_pred = false; | |
620 | break; | |
621 | } | |
622 | one_pred.pred_lhs = gimple_switch_index (gs); | |
623 | one_pred.pred_rhs = CASE_LOW (l); | |
624 | one_pred.cond_code = EQ_EXPR; | |
625 | one_pred.invert = false; | |
626 | t_chain.safe_push (one_pred); | |
627 | has_valid_pred = true; | |
628 | } | |
629 | else | |
34f97b94 XDL |
630 | { |
631 | has_valid_pred = false; | |
632 | break; | |
633 | } | |
34f97b94 XDL |
634 | } |
635 | ||
636 | if (!has_valid_pred) | |
637 | break; | |
927734cf XDL |
638 | else |
639 | preds->safe_push (t_chain); | |
34f97b94 XDL |
640 | } |
641 | return has_valid_pred; | |
642 | } | |
643 | ||
644 | /* Computes all control dependence chains for USE_BB. The control | |
645 | dependence chains are then converted to an array of composite | |
646 | predicates pointed to by PREDS. PHI_BB is the basic block of | |
647 | the phi whose result is used in USE_BB. */ | |
648 | ||
649 | static bool | |
927734cf | 650 | find_predicates (pred_chain_union *preds, |
34f97b94 XDL |
651 | basic_block phi_bb, |
652 | basic_block use_bb) | |
653 | { | |
654 | size_t num_chains = 0, i; | |
92261ce0 JJ |
655 | int num_calls = 0; |
656 | vec<edge> dep_chains[MAX_NUM_CHAINS]; | |
657 | auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain; | |
34f97b94 XDL |
658 | bool has_valid_pred = false; |
659 | basic_block cd_root = 0; | |
660 | ||
34f97b94 XDL |
661 | /* First find the closest bb that is control equivalent to PHI_BB |
662 | that also dominates USE_BB. */ | |
663 | cd_root = phi_bb; | |
664 | while (dominated_by_p (CDI_DOMINATORS, use_bb, cd_root)) | |
665 | { | |
666 | basic_block ctrl_eq_bb = find_control_equiv_block (cd_root); | |
667 | if (ctrl_eq_bb && dominated_by_p (CDI_DOMINATORS, use_bb, ctrl_eq_bb)) | |
668 | cd_root = ctrl_eq_bb; | |
669 | else | |
670 | break; | |
671 | } | |
672 | ||
92261ce0 JJ |
673 | compute_control_dep_chain (cd_root, use_bb, dep_chains, &num_chains, |
674 | &cur_chain, &num_calls); | |
34f97b94 XDL |
675 | |
676 | has_valid_pred | |
92261ce0 | 677 | = convert_control_dep_chain_into_preds (dep_chains, num_chains, preds); |
34f97b94 | 678 | for (i = 0; i < num_chains; i++) |
9771b263 | 679 | dep_chains[i].release (); |
34f97b94 XDL |
680 | return has_valid_pred; |
681 | } | |
682 | ||
683 | /* Computes the set of incoming edges of PHI that have non empty | |
684 | definitions of a phi chain. The collection will be done | |
685 | recursively on operands that are defined by phis. CD_ROOT | |
686 | is the control dependence root. *EDGES holds the result, and | |
687 | VISITED_PHIS is a pointer set for detecting cycles. */ | |
688 | ||
689 | static void | |
538dd0b7 | 690 | collect_phi_def_edges (gphi *phi, basic_block cd_root, |
9771b263 | 691 | vec<edge> *edges, |
6e2830c3 | 692 | hash_set<gimple> *visited_phis) |
34f97b94 XDL |
693 | { |
694 | size_t i, n; | |
695 | edge opnd_edge; | |
696 | tree opnd; | |
697 | ||
6e2830c3 | 698 | if (visited_phis->add (phi)) |
34f97b94 XDL |
699 | return; |
700 | ||
701 | n = gimple_phi_num_args (phi); | |
702 | for (i = 0; i < n; i++) | |
703 | { | |
704 | opnd_edge = gimple_phi_arg_edge (phi, i); | |
705 | opnd = gimple_phi_arg_def (phi, i); | |
706 | ||
e74780a3 XDL |
707 | if (TREE_CODE (opnd) != SSA_NAME) |
708 | { | |
709 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
710 | { | |
711 | fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i); | |
712 | print_gimple_stmt (dump_file, phi, 0, 0); | |
713 | } | |
9771b263 | 714 | edges->safe_push (opnd_edge); |
e74780a3 | 715 | } |
34f97b94 XDL |
716 | else |
717 | { | |
718 | gimple def = SSA_NAME_DEF_STMT (opnd); | |
e74780a3 | 719 | |
34f97b94 XDL |
720 | if (gimple_code (def) == GIMPLE_PHI |
721 | && dominated_by_p (CDI_DOMINATORS, | |
722 | gimple_bb (def), cd_root)) | |
538dd0b7 | 723 | collect_phi_def_edges (as_a <gphi *> (def), cd_root, edges, |
34f97b94 | 724 | visited_phis); |
ba7e83f8 | 725 | else if (!uninit_undefined_value_p (opnd)) |
e74780a3 XDL |
726 | { |
727 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
728 | { | |
729 | fprintf (dump_file, "\n[CHECK] Found def edge %d in ", (int)i); | |
730 | print_gimple_stmt (dump_file, phi, 0, 0); | |
731 | } | |
9771b263 | 732 | edges->safe_push (opnd_edge); |
e74780a3 | 733 | } |
34f97b94 XDL |
734 | } |
735 | } | |
736 | } | |
737 | ||
738 | /* For each use edge of PHI, computes all control dependence chains. | |
739 | The control dependence chains are then converted to an array of | |
740 | composite predicates pointed to by PREDS. */ | |
741 | ||
742 | static bool | |
538dd0b7 | 743 | find_def_preds (pred_chain_union *preds, gphi *phi) |
34f97b94 XDL |
744 | { |
745 | size_t num_chains = 0, i, n; | |
92261ce0 JJ |
746 | vec<edge> dep_chains[MAX_NUM_CHAINS]; |
747 | auto_vec<edge, MAX_CHAIN_LEN + 1> cur_chain; | |
6e1aa848 | 748 | vec<edge> def_edges = vNULL; |
34f97b94 XDL |
749 | bool has_valid_pred = false; |
750 | basic_block phi_bb, cd_root = 0; | |
34f97b94 | 751 | |
34f97b94 XDL |
752 | phi_bb = gimple_bb (phi); |
753 | /* First find the closest dominating bb to be | |
754 | the control dependence root */ | |
755 | cd_root = find_dom (phi_bb); | |
756 | if (!cd_root) | |
757 | return false; | |
758 | ||
6e2830c3 TS |
759 | hash_set<gimple> visited_phis; |
760 | collect_phi_def_edges (phi, cd_root, &def_edges, &visited_phis); | |
34f97b94 | 761 | |
9771b263 | 762 | n = def_edges.length (); |
34f97b94 XDL |
763 | if (n == 0) |
764 | return false; | |
765 | ||
766 | for (i = 0; i < n; i++) | |
767 | { | |
768 | size_t prev_nc, j; | |
92261ce0 | 769 | int num_calls = 0; |
34f97b94 XDL |
770 | edge opnd_edge; |
771 | ||
9771b263 | 772 | opnd_edge = def_edges[i]; |
34f97b94 | 773 | prev_nc = num_chains; |
92261ce0 JJ |
774 | compute_control_dep_chain (cd_root, opnd_edge->src, dep_chains, |
775 | &num_chains, &cur_chain, &num_calls); | |
34f97b94 XDL |
776 | |
777 | /* Now update the newly added chains with | |
778 | the phi operand edge: */ | |
779 | if (EDGE_COUNT (opnd_edge->src->succs) > 1) | |
780 | { | |
92261ce0 JJ |
781 | if (prev_nc == num_chains && num_chains < MAX_NUM_CHAINS) |
782 | dep_chains[num_chains++] = vNULL; | |
34f97b94 | 783 | for (j = prev_nc; j < num_chains; j++) |
92261ce0 | 784 | dep_chains[j].safe_push (opnd_edge); |
34f97b94 XDL |
785 | } |
786 | } | |
787 | ||
788 | has_valid_pred | |
92261ce0 | 789 | = convert_control_dep_chain_into_preds (dep_chains, num_chains, preds); |
34f97b94 | 790 | for (i = 0; i < num_chains; i++) |
9771b263 | 791 | dep_chains[i].release (); |
34f97b94 XDL |
792 | return has_valid_pred; |
793 | } | |
794 | ||
795 | /* Dumps the predicates (PREDS) for USESTMT. */ | |
796 | ||
797 | static void | |
927734cf | 798 | dump_predicates (gimple usestmt, pred_chain_union preds, |
34f97b94 XDL |
799 | const char* msg) |
800 | { | |
801 | size_t i, j; | |
927734cf | 802 | pred_chain one_pred_chain = vNULL; |
81018dcf | 803 | fprintf (dump_file, "%s", msg); |
34f97b94 | 804 | print_gimple_stmt (dump_file, usestmt, 0, 0); |
927734cf XDL |
805 | fprintf (dump_file, "is guarded by :\n\n"); |
806 | size_t num_preds = preds.length (); | |
807 | /* Do some dumping here: */ | |
34f97b94 XDL |
808 | for (i = 0; i < num_preds; i++) |
809 | { | |
810 | size_t np; | |
811 | ||
812 | one_pred_chain = preds[i]; | |
9771b263 | 813 | np = one_pred_chain.length (); |
34f97b94 XDL |
814 | |
815 | for (j = 0; j < np; j++) | |
816 | { | |
927734cf XDL |
817 | pred_info one_pred = one_pred_chain[j]; |
818 | if (one_pred.invert) | |
34f97b94 | 819 | fprintf (dump_file, " (.NOT.) "); |
927734cf XDL |
820 | print_generic_expr (dump_file, one_pred.pred_lhs, 0); |
821 | fprintf (dump_file, " %s ", op_symbol_code (one_pred.cond_code)); | |
822 | print_generic_expr (dump_file, one_pred.pred_rhs, 0); | |
34f97b94 | 823 | if (j < np - 1) |
927734cf XDL |
824 | fprintf (dump_file, " (.AND.) "); |
825 | else | |
826 | fprintf (dump_file, "\n"); | |
34f97b94 XDL |
827 | } |
828 | if (i < num_preds - 1) | |
829 | fprintf (dump_file, "(.OR.)\n"); | |
927734cf XDL |
830 | else |
831 | fprintf (dump_file, "\n\n"); | |
34f97b94 XDL |
832 | } |
833 | } | |
834 | ||
835 | /* Destroys the predicate set *PREDS. */ | |
836 | ||
837 | static void | |
927734cf | 838 | destroy_predicate_vecs (pred_chain_union preds) |
34f97b94 | 839 | { |
927734cf XDL |
840 | size_t i; |
841 | ||
842 | size_t n = preds.length (); | |
34f97b94 | 843 | for (i = 0; i < n; i++) |
927734cf XDL |
844 | preds[i].release (); |
845 | preds.release (); | |
34f97b94 XDL |
846 | } |
847 | ||
848 | ||
927734cf | 849 | /* Computes the 'normalized' conditional code with operand |
34f97b94 XDL |
850 | swapping and condition inversion. */ |
851 | ||
852 | static enum tree_code | |
853 | get_cmp_code (enum tree_code orig_cmp_code, | |
854 | bool swap_cond, bool invert) | |
855 | { | |
856 | enum tree_code tc = orig_cmp_code; | |
857 | ||
858 | if (swap_cond) | |
859 | tc = swap_tree_comparison (orig_cmp_code); | |
860 | if (invert) | |
861 | tc = invert_tree_comparison (tc, false); | |
862 | ||
863 | switch (tc) | |
864 | { | |
865 | case LT_EXPR: | |
866 | case LE_EXPR: | |
867 | case GT_EXPR: | |
868 | case GE_EXPR: | |
869 | case EQ_EXPR: | |
870 | case NE_EXPR: | |
871 | break; | |
872 | default: | |
873 | return ERROR_MARK; | |
874 | } | |
875 | return tc; | |
876 | } | |
877 | ||
878 | /* Returns true if VAL falls in the range defined by BOUNDARY and CMPC, i.e. | |
879 | all values in the range satisfies (x CMPC BOUNDARY) == true. */ | |
880 | ||
881 | static bool | |
882 | is_value_included_in (tree val, tree boundary, enum tree_code cmpc) | |
883 | { | |
884 | bool inverted = false; | |
885 | bool is_unsigned; | |
886 | bool result; | |
887 | ||
888 | /* Only handle integer constant here. */ | |
889 | if (TREE_CODE (val) != INTEGER_CST | |
890 | || TREE_CODE (boundary) != INTEGER_CST) | |
891 | return true; | |
892 | ||
893 | is_unsigned = TYPE_UNSIGNED (TREE_TYPE (val)); | |
894 | ||
895 | if (cmpc == GE_EXPR || cmpc == GT_EXPR | |
896 | || cmpc == NE_EXPR) | |
897 | { | |
898 | cmpc = invert_tree_comparison (cmpc, false); | |
899 | inverted = true; | |
900 | } | |
901 | ||
902 | if (is_unsigned) | |
903 | { | |
904 | if (cmpc == EQ_EXPR) | |
905 | result = tree_int_cst_equal (val, boundary); | |
906 | else if (cmpc == LT_EXPR) | |
807e902e | 907 | result = tree_int_cst_lt (val, boundary); |
34f97b94 XDL |
908 | else |
909 | { | |
910 | gcc_assert (cmpc == LE_EXPR); | |
807e902e | 911 | result = tree_int_cst_le (val, boundary); |
34f97b94 XDL |
912 | } |
913 | } | |
914 | else | |
915 | { | |
916 | if (cmpc == EQ_EXPR) | |
917 | result = tree_int_cst_equal (val, boundary); | |
918 | else if (cmpc == LT_EXPR) | |
807e902e | 919 | result = tree_int_cst_lt (val, boundary); |
34f97b94 XDL |
920 | else |
921 | { | |
922 | gcc_assert (cmpc == LE_EXPR); | |
923 | result = (tree_int_cst_equal (val, boundary) | |
807e902e | 924 | || tree_int_cst_lt (val, boundary)); |
34f97b94 XDL |
925 | } |
926 | } | |
927 | ||
928 | if (inverted) | |
929 | result ^= 1; | |
930 | ||
931 | return result; | |
932 | } | |
933 | ||
934 | /* Returns true if PRED is common among all the predicate | |
935 | chains (PREDS) (and therefore can be factored out). | |
936 | NUM_PRED_CHAIN is the size of array PREDS. */ | |
937 | ||
938 | static bool | |
927734cf XDL |
939 | find_matching_predicate_in_rest_chains (pred_info pred, |
940 | pred_chain_union preds, | |
34f97b94 XDL |
941 | size_t num_pred_chains) |
942 | { | |
943 | size_t i, j, n; | |
944 | ||
927734cf | 945 | /* Trival case. */ |
34f97b94 XDL |
946 | if (num_pred_chains == 1) |
947 | return true; | |
948 | ||
949 | for (i = 1; i < num_pred_chains; i++) | |
950 | { | |
951 | bool found = false; | |
927734cf | 952 | pred_chain one_chain = preds[i]; |
9771b263 | 953 | n = one_chain.length (); |
34f97b94 XDL |
954 | for (j = 0; j < n; j++) |
955 | { | |
927734cf XDL |
956 | pred_info pred2 = one_chain[j]; |
957 | /* Can relax the condition comparison to not | |
34f97b94 XDL |
958 | use address comparison. However, the most common |
959 | case is that multiple control dependent paths share | |
960 | a common path prefix, so address comparison should | |
961 | be ok. */ | |
962 | ||
927734cf XDL |
963 | if (operand_equal_p (pred2.pred_lhs, pred.pred_lhs, 0) |
964 | && operand_equal_p (pred2.pred_rhs, pred.pred_rhs, 0) | |
965 | && pred2.invert == pred.invert) | |
34f97b94 XDL |
966 | { |
967 | found = true; | |
968 | break; | |
969 | } | |
970 | } | |
971 | if (!found) | |
972 | return false; | |
973 | } | |
974 | return true; | |
975 | } | |
976 | ||
977 | /* Forward declaration. */ | |
978 | static bool | |
979 | is_use_properly_guarded (gimple use_stmt, | |
980 | basic_block use_bb, | |
538dd0b7 | 981 | gphi *phi, |
34f97b94 | 982 | unsigned uninit_opnds, |
c0503346 | 983 | pred_chain_union *def_preds, |
538dd0b7 | 984 | hash_set<gphi *> *visited_phis); |
34f97b94 | 985 | |
2edb37a6 XDL |
986 | /* Returns true if all uninitialized opnds are pruned. Returns false |
987 | otherwise. PHI is the phi node with uninitialized operands, | |
988 | UNINIT_OPNDS is the bitmap of the uninitialize operand positions, | |
989 | FLAG_DEF is the statement defining the flag guarding the use of the | |
990 | PHI output, BOUNDARY_CST is the const value used in the predicate | |
991 | associated with the flag, CMP_CODE is the comparison code used in | |
992 | the predicate, VISITED_PHIS is the pointer set of phis visited, and | |
993 | VISITED_FLAG_PHIS is the pointer to the pointer set of flag definitions | |
994 | that are also phis. | |
995 | ||
996 | Example scenario: | |
997 | ||
998 | BB1: | |
999 | flag_1 = phi <0, 1> // (1) | |
1000 | var_1 = phi <undef, some_val> | |
1001 | ||
1002 | ||
1003 | BB2: | |
1004 | flag_2 = phi <0, flag_1, flag_1> // (2) | |
1005 | var_2 = phi <undef, var_1, var_1> | |
1006 | if (flag_2 == 1) | |
1007 | goto BB3; | |
1008 | ||
1009 | BB3: | |
1010 | use of var_2 // (3) | |
1011 | ||
1012 | Because some flag arg in (1) is not constant, if we do not look into the | |
1013 | flag phis recursively, it is conservatively treated as unknown and var_1 | |
1014 | is thought to be flowed into use at (3). Since var_1 is potentially uninitialized | |
1015 | a false warning will be emitted. Checking recursively into (1), the compiler can | |
1016 | find out that only some_val (which is defined) can flow into (3) which is OK. | |
1017 | ||
1018 | */ | |
1019 | ||
1020 | static bool | |
538dd0b7 | 1021 | prune_uninit_phi_opnds_in_unrealizable_paths (gphi *phi, |
927734cf | 1022 | unsigned uninit_opnds, |
538dd0b7 | 1023 | gphi *flag_def, |
927734cf XDL |
1024 | tree boundary_cst, |
1025 | enum tree_code cmp_code, | |
538dd0b7 | 1026 | hash_set<gphi *> *visited_phis, |
927734cf | 1027 | bitmap *visited_flag_phis) |
2edb37a6 XDL |
1028 | { |
1029 | unsigned i; | |
1030 | ||
1031 | for (i = 0; i < MIN (32, gimple_phi_num_args (flag_def)); i++) | |
1032 | { | |
1033 | tree flag_arg; | |
1034 | ||
1035 | if (!MASK_TEST_BIT (uninit_opnds, i)) | |
1036 | continue; | |
1037 | ||
1038 | flag_arg = gimple_phi_arg_def (flag_def, i); | |
1039 | if (!is_gimple_constant (flag_arg)) | |
1040 | { | |
538dd0b7 | 1041 | gphi *flag_arg_def, *phi_arg_def; |
2edb37a6 XDL |
1042 | tree phi_arg; |
1043 | unsigned uninit_opnds_arg_phi; | |
1044 | ||
1045 | if (TREE_CODE (flag_arg) != SSA_NAME) | |
1046 | return false; | |
538dd0b7 DM |
1047 | flag_arg_def = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (flag_arg)); |
1048 | if (!flag_arg_def) | |
2edb37a6 XDL |
1049 | return false; |
1050 | ||
1051 | phi_arg = gimple_phi_arg_def (phi, i); | |
1052 | if (TREE_CODE (phi_arg) != SSA_NAME) | |
1053 | return false; | |
1054 | ||
538dd0b7 DM |
1055 | phi_arg_def = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (phi_arg)); |
1056 | if (!phi_arg_def) | |
2edb37a6 XDL |
1057 | return false; |
1058 | ||
1059 | if (gimple_bb (phi_arg_def) != gimple_bb (flag_arg_def)) | |
1060 | return false; | |
1061 | ||
1062 | if (!*visited_flag_phis) | |
1063 | *visited_flag_phis = BITMAP_ALLOC (NULL); | |
1064 | ||
1065 | if (bitmap_bit_p (*visited_flag_phis, | |
1066 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def)))) | |
1067 | return false; | |
1068 | ||
1069 | bitmap_set_bit (*visited_flag_phis, | |
1070 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def))); | |
1071 | ||
1072 | /* Now recursively prune the uninitialized phi args. */ | |
1073 | uninit_opnds_arg_phi = compute_uninit_opnds_pos (phi_arg_def); | |
927734cf XDL |
1074 | if (!prune_uninit_phi_opnds_in_unrealizable_paths |
1075 | (phi_arg_def, uninit_opnds_arg_phi, flag_arg_def, | |
1076 | boundary_cst, cmp_code, visited_phis, visited_flag_phis)) | |
2edb37a6 XDL |
1077 | return false; |
1078 | ||
1079 | bitmap_clear_bit (*visited_flag_phis, | |
1080 | SSA_NAME_VERSION (gimple_phi_result (flag_arg_def))); | |
1081 | continue; | |
1082 | } | |
1083 | ||
1084 | /* Now check if the constant is in the guarded range. */ | |
1085 | if (is_value_included_in (flag_arg, boundary_cst, cmp_code)) | |
1086 | { | |
1087 | tree opnd; | |
1088 | gimple opnd_def; | |
1089 | ||
1090 | /* Now that we know that this undefined edge is not | |
1091 | pruned. If the operand is defined by another phi, | |
1092 | we can further prune the incoming edges of that | |
1093 | phi by checking the predicates of this operands. */ | |
1094 | ||
1095 | opnd = gimple_phi_arg_def (phi, i); | |
1096 | opnd_def = SSA_NAME_DEF_STMT (opnd); | |
538dd0b7 | 1097 | if (gphi *opnd_def_phi = dyn_cast <gphi *> (opnd_def)) |
2edb37a6 XDL |
1098 | { |
1099 | edge opnd_edge; | |
1100 | unsigned uninit_opnds2 | |
538dd0b7 | 1101 | = compute_uninit_opnds_pos (opnd_def_phi); |
c0503346 PP |
1102 | pred_chain_union def_preds = vNULL; |
1103 | bool ok; | |
2edb37a6 XDL |
1104 | gcc_assert (!MASK_EMPTY (uninit_opnds2)); |
1105 | opnd_edge = gimple_phi_arg_edge (phi, i); | |
c0503346 PP |
1106 | ok = is_use_properly_guarded (phi, |
1107 | opnd_edge->src, | |
1108 | opnd_def_phi, | |
1109 | uninit_opnds2, | |
1110 | &def_preds, | |
1111 | visited_phis); | |
1112 | destroy_predicate_vecs (def_preds); | |
1113 | if (!ok) | |
1114 | return false; | |
2edb37a6 XDL |
1115 | } |
1116 | else | |
1117 | return false; | |
1118 | } | |
1119 | } | |
1120 | ||
1121 | return true; | |
1122 | } | |
1123 | ||
34f97b94 XDL |
1124 | /* A helper function that determines if the predicate set |
1125 | of the use is not overlapping with that of the uninit paths. | |
1126 | The most common senario of guarded use is in Example 1: | |
1127 | Example 1: | |
1128 | if (some_cond) | |
1129 | { | |
1130 | x = ...; | |
1131 | flag = true; | |
1132 | } | |
1133 | ||
1134 | ... some code ... | |
1135 | ||
1136 | if (flag) | |
1137 | use (x); | |
1138 | ||
1139 | The real world examples are usually more complicated, but similar | |
1140 | and usually result from inlining: | |
1141 | ||
1142 | bool init_func (int * x) | |
1143 | { | |
1144 | if (some_cond) | |
1145 | return false; | |
1146 | *x = .. | |
1147 | return true; | |
1148 | } | |
1149 | ||
1150 | void foo(..) | |
1151 | { | |
1152 | int x; | |
1153 | ||
1154 | if (!init_func(&x)) | |
1155 | return; | |
1156 | ||
1157 | .. some_code ... | |
1158 | use (x); | |
1159 | } | |
1160 | ||
1161 | Another possible use scenario is in the following trivial example: | |
1162 | ||
1163 | Example 2: | |
1164 | if (n > 0) | |
1165 | x = 1; | |
1166 | ... | |
1167 | if (n > 0) | |
1168 | { | |
1169 | if (m < 2) | |
1170 | .. = x; | |
1171 | } | |
1172 | ||
1173 | Predicate analysis needs to compute the composite predicate: | |
1174 | ||
1175 | 1) 'x' use predicate: (n > 0) .AND. (m < 2) | |
1176 | 2) 'x' default value (non-def) predicate: .NOT. (n > 0) | |
1177 | (the predicate chain for phi operand defs can be computed | |
1178 | starting from a bb that is control equivalent to the phi's | |
1179 | bb and is dominating the operand def.) | |
1180 | ||
1181 | and check overlapping: | |
1182 | (n > 0) .AND. (m < 2) .AND. (.NOT. (n > 0)) | |
1183 | <==> false | |
1184 | ||
1185 | This implementation provides framework that can handle | |
1186 | scenarios. (Note that many simple cases are handled properly | |
1187 | without the predicate analysis -- this is due to jump threading | |
1188 | transformation which eliminates the merge point thus makes | |
1189 | path sensitive analysis unnecessary.) | |
1190 | ||
1191 | NUM_PREDS is the number is the number predicate chains, PREDS is | |
1192 | the array of chains, PHI is the phi node whose incoming (undefined) | |
1193 | paths need to be pruned, and UNINIT_OPNDS is the bitmap holding | |
1194 | uninit operand positions. VISITED_PHIS is the pointer set of phi | |
1195 | stmts being checked. */ | |
1196 | ||
1197 | ||
1198 | static bool | |
927734cf | 1199 | use_pred_not_overlap_with_undef_path_pred (pred_chain_union preds, |
538dd0b7 DM |
1200 | gphi *phi, unsigned uninit_opnds, |
1201 | hash_set<gphi *> *visited_phis) | |
34f97b94 XDL |
1202 | { |
1203 | unsigned int i, n; | |
1204 | gimple flag_def = 0; | |
1205 | tree boundary_cst = 0; | |
1206 | enum tree_code cmp_code; | |
1207 | bool swap_cond = false; | |
1208 | bool invert = false; | |
927734cf | 1209 | pred_chain the_pred_chain = vNULL; |
2edb37a6 XDL |
1210 | bitmap visited_flag_phis = NULL; |
1211 | bool all_pruned = false; | |
927734cf | 1212 | size_t num_preds = preds.length (); |
34f97b94 XDL |
1213 | |
1214 | gcc_assert (num_preds > 0); | |
1215 | /* Find within the common prefix of multiple predicate chains | |
1216 | a predicate that is a comparison of a flag variable against | |
1217 | a constant. */ | |
1218 | the_pred_chain = preds[0]; | |
9771b263 | 1219 | n = the_pred_chain.length (); |
34f97b94 XDL |
1220 | for (i = 0; i < n; i++) |
1221 | { | |
34f97b94 XDL |
1222 | tree cond_lhs, cond_rhs, flag = 0; |
1223 | ||
927734cf | 1224 | pred_info the_pred = the_pred_chain[i]; |
34f97b94 | 1225 | |
927734cf XDL |
1226 | invert = the_pred.invert; |
1227 | cond_lhs = the_pred.pred_lhs; | |
1228 | cond_rhs = the_pred.pred_rhs; | |
1229 | cmp_code = the_pred.cond_code; | |
34f97b94 XDL |
1230 | |
1231 | if (cond_lhs != NULL_TREE && TREE_CODE (cond_lhs) == SSA_NAME | |
1232 | && cond_rhs != NULL_TREE && is_gimple_constant (cond_rhs)) | |
1233 | { | |
1234 | boundary_cst = cond_rhs; | |
1235 | flag = cond_lhs; | |
1236 | } | |
1237 | else if (cond_rhs != NULL_TREE && TREE_CODE (cond_rhs) == SSA_NAME | |
1238 | && cond_lhs != NULL_TREE && is_gimple_constant (cond_lhs)) | |
1239 | { | |
1240 | boundary_cst = cond_lhs; | |
1241 | flag = cond_rhs; | |
1242 | swap_cond = true; | |
1243 | } | |
1244 | ||
1245 | if (!flag) | |
1246 | continue; | |
1247 | ||
1248 | flag_def = SSA_NAME_DEF_STMT (flag); | |
1249 | ||
1250 | if (!flag_def) | |
1251 | continue; | |
1252 | ||
1253 | if ((gimple_code (flag_def) == GIMPLE_PHI) | |
1254 | && (gimple_bb (flag_def) == gimple_bb (phi)) | |
927734cf XDL |
1255 | && find_matching_predicate_in_rest_chains (the_pred, preds, |
1256 | num_preds)) | |
34f97b94 XDL |
1257 | break; |
1258 | ||
1259 | flag_def = 0; | |
1260 | } | |
1261 | ||
1262 | if (!flag_def) | |
1263 | return false; | |
1264 | ||
1265 | /* Now check all the uninit incoming edge has a constant flag value | |
1266 | that is in conflict with the use guard/predicate. */ | |
1267 | cmp_code = get_cmp_code (cmp_code, swap_cond, invert); | |
1268 | ||
1269 | if (cmp_code == ERROR_MARK) | |
1270 | return false; | |
1271 | ||
2edb37a6 XDL |
1272 | all_pruned = prune_uninit_phi_opnds_in_unrealizable_paths (phi, |
1273 | uninit_opnds, | |
538dd0b7 | 1274 | as_a <gphi *> (flag_def), |
2edb37a6 XDL |
1275 | boundary_cst, |
1276 | cmp_code, | |
1277 | visited_phis, | |
1278 | &visited_flag_phis); | |
34f97b94 | 1279 | |
2edb37a6 XDL |
1280 | if (visited_flag_phis) |
1281 | BITMAP_FREE (visited_flag_phis); | |
34f97b94 | 1282 | |
2edb37a6 | 1283 | return all_pruned; |
34f97b94 XDL |
1284 | } |
1285 | ||
927734cf XDL |
1286 | /* The helper function returns true if two predicates X1 and X2 |
1287 | are equivalent. It assumes the expressions have already | |
1288 | properly re-associated. */ | |
34f97b94 XDL |
1289 | |
1290 | static inline bool | |
927734cf | 1291 | pred_equal_p (pred_info x1, pred_info x2) |
34f97b94 | 1292 | { |
927734cf XDL |
1293 | enum tree_code c1, c2; |
1294 | if (!operand_equal_p (x1.pred_lhs, x2.pred_lhs, 0) | |
1295 | || !operand_equal_p (x1.pred_rhs, x2.pred_rhs, 0)) | |
1296 | return false; | |
34f97b94 | 1297 | |
927734cf XDL |
1298 | c1 = x1.cond_code; |
1299 | if (x1.invert != x2.invert) | |
1300 | c2 = invert_tree_comparison (x2.cond_code, false); | |
1301 | else | |
1302 | c2 = x2.cond_code; | |
34f97b94 | 1303 | |
927734cf XDL |
1304 | return c1 == c2; |
1305 | } | |
34f97b94 | 1306 | |
927734cf | 1307 | /* Returns true if the predication is testing !=. */ |
34f97b94 | 1308 | |
927734cf XDL |
1309 | static inline bool |
1310 | is_neq_relop_p (pred_info pred) | |
34f97b94 | 1311 | { |
34f97b94 | 1312 | |
927734cf XDL |
1313 | return (pred.cond_code == NE_EXPR && !pred.invert) |
1314 | || (pred.cond_code == EQ_EXPR && pred.invert); | |
34f97b94 XDL |
1315 | } |
1316 | ||
927734cf | 1317 | /* Returns true if pred is of the form X != 0. */ |
34f97b94 | 1318 | |
927734cf XDL |
1319 | static inline bool |
1320 | is_neq_zero_form_p (pred_info pred) | |
34f97b94 | 1321 | { |
927734cf XDL |
1322 | if (!is_neq_relop_p (pred) || !integer_zerop (pred.pred_rhs) |
1323 | || TREE_CODE (pred.pred_lhs) != SSA_NAME) | |
1324 | return false; | |
1325 | return true; | |
1326 | } | |
34f97b94 | 1327 | |
927734cf XDL |
1328 | /* The helper function returns true if two predicates X1 |
1329 | is equivalent to X2 != 0. */ | |
34f97b94 | 1330 | |
927734cf XDL |
1331 | static inline bool |
1332 | pred_expr_equal_p (pred_info x1, tree x2) | |
1333 | { | |
1334 | if (!is_neq_zero_form_p (x1)) | |
1335 | return false; | |
34f97b94 | 1336 | |
927734cf | 1337 | return operand_equal_p (x1.pred_lhs, x2, 0); |
34f97b94 XDL |
1338 | } |
1339 | ||
927734cf XDL |
1340 | /* Returns true of the domain of single predicate expression |
1341 | EXPR1 is a subset of that of EXPR2. Returns false if it | |
1342 | can not be proved. */ | |
34f97b94 XDL |
1343 | |
1344 | static bool | |
927734cf | 1345 | is_pred_expr_subset_of (pred_info expr1, pred_info expr2) |
34f97b94 | 1346 | { |
927734cf | 1347 | enum tree_code code1, code2; |
34f97b94 | 1348 | |
927734cf | 1349 | if (pred_equal_p (expr1, expr2)) |
34f97b94 XDL |
1350 | return true; |
1351 | ||
927734cf XDL |
1352 | if ((TREE_CODE (expr1.pred_rhs) != INTEGER_CST) |
1353 | || (TREE_CODE (expr2.pred_rhs) != INTEGER_CST)) | |
1354 | return false; | |
34f97b94 | 1355 | |
927734cf XDL |
1356 | if (!operand_equal_p (expr1.pred_lhs, expr2.pred_lhs, 0)) |
1357 | return false; | |
34f97b94 | 1358 | |
927734cf XDL |
1359 | code1 = expr1.cond_code; |
1360 | if (expr1.invert) | |
1361 | code1 = invert_tree_comparison (code1, false); | |
1362 | code2 = expr2.cond_code; | |
1363 | if (expr2.invert) | |
1364 | code2 = invert_tree_comparison (code2, false); | |
34f97b94 | 1365 | |
3cd58c0f RB |
1366 | if ((code1 == EQ_EXPR || code1 == BIT_AND_EXPR) |
1367 | && code2 == BIT_AND_EXPR) | |
666e8e06 RB |
1368 | return wi::eq_p (expr1.pred_rhs, |
1369 | wi::bit_and (expr1.pred_rhs, expr2.pred_rhs)); | |
1370 | ||
927734cf XDL |
1371 | if (code1 != code2 && code2 != NE_EXPR) |
1372 | return false; | |
34f97b94 | 1373 | |
927734cf XDL |
1374 | if (is_value_included_in (expr1.pred_rhs, expr2.pred_rhs, code2)) |
1375 | return true; | |
34f97b94 | 1376 | |
927734cf XDL |
1377 | return false; |
1378 | } | |
34f97b94 | 1379 | |
927734cf XDL |
1380 | /* Returns true if the domain of PRED1 is a subset |
1381 | of that of PRED2. Returns false if it can not be proved so. */ | |
34f97b94 | 1382 | |
927734cf XDL |
1383 | static bool |
1384 | is_pred_chain_subset_of (pred_chain pred1, | |
1385 | pred_chain pred2) | |
1386 | { | |
1387 | size_t np1, np2, i1, i2; | |
34f97b94 | 1388 | |
927734cf XDL |
1389 | np1 = pred1.length (); |
1390 | np2 = pred2.length (); | |
34f97b94 | 1391 | |
927734cf | 1392 | for (i2 = 0; i2 < np2; i2++) |
34f97b94 | 1393 | { |
927734cf XDL |
1394 | bool found = false; |
1395 | pred_info info2 = pred2[i2]; | |
1396 | for (i1 = 0; i1 < np1; i1++) | |
1397 | { | |
1398 | pred_info info1 = pred1[i1]; | |
1399 | if (is_pred_expr_subset_of (info1, info2)) | |
1400 | { | |
1401 | found = true; | |
1402 | break; | |
1403 | } | |
1404 | } | |
1405 | if (!found) | |
1406 | return false; | |
34f97b94 | 1407 | } |
927734cf | 1408 | return true; |
34f97b94 XDL |
1409 | } |
1410 | ||
927734cf XDL |
1411 | /* Returns true if the domain defined by |
1412 | one pred chain ONE_PRED is a subset of the domain | |
1413 | of *PREDS. It returns false if ONE_PRED's domain is | |
1414 | not a subset of any of the sub-domains of PREDS | |
1415 | (corresponding to each individual chains in it), even | |
1416 | though it may be still be a subset of whole domain | |
1417 | of PREDS which is the union (ORed) of all its subdomains. | |
1418 | In other words, the result is conservative. */ | |
34f97b94 XDL |
1419 | |
1420 | static bool | |
927734cf | 1421 | is_included_in (pred_chain one_pred, pred_chain_union preds) |
34f97b94 XDL |
1422 | { |
1423 | size_t i; | |
927734cf | 1424 | size_t n = preds.length (); |
34f97b94 | 1425 | |
927734cf | 1426 | for (i = 0; i < n; i++) |
34f97b94 | 1427 | { |
927734cf | 1428 | if (is_pred_chain_subset_of (one_pred, preds[i])) |
34f97b94 XDL |
1429 | return true; |
1430 | } | |
927734cf | 1431 | |
34f97b94 XDL |
1432 | return false; |
1433 | } | |
1434 | ||
927734cf XDL |
1435 | /* Compares two predicate sets PREDS1 and PREDS2 and returns |
1436 | true if the domain defined by PREDS1 is a superset | |
1437 | of PREDS2's domain. N1 and N2 are array sizes of PREDS1 and | |
1438 | PREDS2 respectively. The implementation chooses not to build | |
1439 | generic trees (and relying on the folding capability of the | |
1440 | compiler), but instead performs brute force comparison of | |
1441 | individual predicate chains (won't be a compile time problem | |
1442 | as the chains are pretty short). When the function returns | |
1443 | false, it does not necessarily mean *PREDS1 is not a superset | |
1444 | of *PREDS2, but mean it may not be so since the analysis can | |
1445 | not prove it. In such cases, false warnings may still be | |
1446 | emitted. */ | |
34f97b94 XDL |
1447 | |
1448 | static bool | |
927734cf | 1449 | is_superset_of (pred_chain_union preds1, pred_chain_union preds2) |
34f97b94 | 1450 | { |
927734cf XDL |
1451 | size_t i, n2; |
1452 | pred_chain one_pred_chain = vNULL; | |
34f97b94 | 1453 | |
927734cf XDL |
1454 | n2 = preds2.length (); |
1455 | ||
1456 | for (i = 0; i < n2; i++) | |
34f97b94 | 1457 | { |
927734cf XDL |
1458 | one_pred_chain = preds2[i]; |
1459 | if (!is_included_in (one_pred_chain, preds1)) | |
34f97b94 XDL |
1460 | return false; |
1461 | } | |
927734cf | 1462 | |
34f97b94 XDL |
1463 | return true; |
1464 | } | |
1465 | ||
927734cf | 1466 | /* Returns true if TC is AND or OR. */ |
34f97b94 | 1467 | |
927734cf XDL |
1468 | static inline bool |
1469 | is_and_or_or_p (enum tree_code tc, tree type) | |
34f97b94 | 1470 | { |
927734cf XDL |
1471 | return (tc == BIT_IOR_EXPR |
1472 | || (tc == BIT_AND_EXPR | |
1473 | && (type == 0 || TREE_CODE (type) == BOOLEAN_TYPE))); | |
1474 | } | |
34f97b94 | 1475 | |
927734cf XDL |
1476 | /* Returns true if X1 is the negate of X2. */ |
1477 | ||
1478 | static inline bool | |
1479 | pred_neg_p (pred_info x1, pred_info x2) | |
1480 | { | |
1481 | enum tree_code c1, c2; | |
1482 | if (!operand_equal_p (x1.pred_lhs, x2.pred_lhs, 0) | |
1483 | || !operand_equal_p (x1.pred_rhs, x2.pred_rhs, 0)) | |
1484 | return false; | |
1485 | ||
1486 | c1 = x1.cond_code; | |
1487 | if (x1.invert == x2.invert) | |
1488 | c2 = invert_tree_comparison (x2.cond_code, false); | |
1489 | else | |
1490 | c2 = x2.cond_code; | |
1491 | ||
1492 | return c1 == c2; | |
34f97b94 XDL |
1493 | } |
1494 | ||
927734cf XDL |
1495 | /* 1) ((x IOR y) != 0) AND (x != 0) is equivalent to (x != 0); |
1496 | 2) (X AND Y) OR (!X AND Y) is equivalent to Y; | |
1497 | 3) X OR (!X AND Y) is equivalent to (X OR Y); | |
1498 | 4) ((x IAND y) != 0) || (x != 0 AND y != 0)) is equivalent to | |
1499 | (x != 0 AND y != 0) | |
1500 | 5) (X AND Y) OR (!X AND Z) OR (!Y AND Z) is equivalent to | |
1501 | (X AND Y) OR Z | |
34f97b94 | 1502 | |
927734cf XDL |
1503 | PREDS is the predicate chains, and N is the number of chains. */ |
1504 | ||
1505 | /* Helper function to implement rule 1 above. ONE_CHAIN is | |
1506 | the AND predication to be simplified. */ | |
1507 | ||
1508 | static void | |
1509 | simplify_pred (pred_chain *one_chain) | |
34f97b94 | 1510 | { |
927734cf XDL |
1511 | size_t i, j, n; |
1512 | bool simplified = false; | |
1513 | pred_chain s_chain = vNULL; | |
34f97b94 | 1514 | |
927734cf | 1515 | n = one_chain->length (); |
34f97b94 | 1516 | |
927734cf | 1517 | for (i = 0; i < n; i++) |
34f97b94 | 1518 | { |
927734cf XDL |
1519 | pred_info *a_pred = &(*one_chain)[i]; |
1520 | ||
1521 | if (!a_pred->pred_lhs) | |
1522 | continue; | |
1523 | if (!is_neq_zero_form_p (*a_pred)) | |
1524 | continue; | |
1525 | ||
1526 | gimple def_stmt = SSA_NAME_DEF_STMT (a_pred->pred_lhs); | |
1527 | if (gimple_code (def_stmt) != GIMPLE_ASSIGN) | |
1528 | continue; | |
1529 | if (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR) | |
34f97b94 | 1530 | { |
927734cf | 1531 | for (j = 0; j < n; j++) |
34f97b94 | 1532 | { |
927734cf XDL |
1533 | pred_info *b_pred = &(*one_chain)[j]; |
1534 | ||
1535 | if (!b_pred->pred_lhs) | |
1536 | continue; | |
1537 | if (!is_neq_zero_form_p (*b_pred)) | |
1538 | continue; | |
1539 | ||
1540 | if (pred_expr_equal_p (*b_pred, gimple_assign_rhs1 (def_stmt)) | |
1541 | || pred_expr_equal_p (*b_pred, gimple_assign_rhs2 (def_stmt))) | |
1542 | { | |
1543 | /* Mark a_pred for removal. */ | |
1544 | a_pred->pred_lhs = NULL; | |
1545 | a_pred->pred_rhs = NULL; | |
1546 | simplified = true; | |
1547 | break; | |
1548 | } | |
34f97b94 | 1549 | } |
34f97b94 XDL |
1550 | } |
1551 | } | |
34f97b94 | 1552 | |
927734cf XDL |
1553 | if (!simplified) |
1554 | return; | |
34f97b94 | 1555 | |
927734cf XDL |
1556 | for (i = 0; i < n; i++) |
1557 | { | |
1558 | pred_info *a_pred = &(*one_chain)[i]; | |
1559 | if (!a_pred->pred_lhs) | |
1560 | continue; | |
1561 | s_chain.safe_push (*a_pred); | |
34f97b94 | 1562 | } |
927734cf XDL |
1563 | |
1564 | one_chain->release (); | |
1565 | *one_chain = s_chain; | |
34f97b94 XDL |
1566 | } |
1567 | ||
927734cf XDL |
1568 | /* The helper function implements the rule 2 for the |
1569 | OR predicate PREDS. | |
1570 | ||
1571 | 2) (X AND Y) OR (!X AND Y) is equivalent to Y. */ | |
34f97b94 XDL |
1572 | |
1573 | static bool | |
927734cf | 1574 | simplify_preds_2 (pred_chain_union *preds) |
34f97b94 | 1575 | { |
927734cf XDL |
1576 | size_t i, j, n; |
1577 | bool simplified = false; | |
1578 | pred_chain_union s_preds = vNULL; | |
34f97b94 | 1579 | |
927734cf XDL |
1580 | /* (X AND Y) OR (!X AND Y) is equivalent to Y. |
1581 | (X AND Y) OR (X AND !Y) is equivalent to X. */ | |
34f97b94 | 1582 | |
927734cf XDL |
1583 | n = preds->length (); |
1584 | for (i = 0; i < n; i++) | |
1585 | { | |
1586 | pred_info x, y; | |
1587 | pred_chain *a_chain = &(*preds)[i]; | |
34f97b94 | 1588 | |
927734cf XDL |
1589 | if (a_chain->length () != 2) |
1590 | continue; | |
1591 | ||
1592 | x = (*a_chain)[0]; | |
1593 | y = (*a_chain)[1]; | |
1594 | ||
1595 | for (j = 0; j < n; j++) | |
1596 | { | |
1597 | pred_chain *b_chain; | |
1598 | pred_info x2, y2; | |
1599 | ||
1600 | if (j == i) | |
1601 | continue; | |
1602 | ||
1603 | b_chain = &(*preds)[j]; | |
1604 | if (b_chain->length () != 2) | |
1605 | continue; | |
34f97b94 | 1606 | |
927734cf XDL |
1607 | x2 = (*b_chain)[0]; |
1608 | y2 = (*b_chain)[1]; | |
34f97b94 | 1609 | |
927734cf XDL |
1610 | if (pred_equal_p (x, x2) && pred_neg_p (y, y2)) |
1611 | { | |
1612 | /* Kill a_chain. */ | |
1613 | a_chain->release (); | |
1614 | b_chain->release (); | |
1615 | b_chain->safe_push (x); | |
1616 | simplified = true; | |
1617 | break; | |
1618 | } | |
1619 | if (pred_neg_p (x, x2) && pred_equal_p (y, y2)) | |
1620 | { | |
1621 | /* Kill a_chain. */ | |
1622 | a_chain->release (); | |
1623 | b_chain->release (); | |
1624 | b_chain->safe_push (y); | |
1625 | simplified = true; | |
1626 | break; | |
1627 | } | |
1628 | } | |
1629 | } | |
1630 | /* Now clean up the chain. */ | |
1631 | if (simplified) | |
1632 | { | |
1633 | for (i = 0; i < n; i++) | |
1634 | { | |
1635 | if ((*preds)[i].is_empty ()) | |
1636 | continue; | |
1637 | s_preds.safe_push ((*preds)[i]); | |
1638 | } | |
1639 | preds->release (); | |
1640 | (*preds) = s_preds; | |
1641 | s_preds = vNULL; | |
1642 | } | |
34f97b94 | 1643 | |
927734cf | 1644 | return simplified; |
34f97b94 XDL |
1645 | } |
1646 | ||
927734cf XDL |
1647 | /* The helper function implements the rule 2 for the |
1648 | OR predicate PREDS. | |
1649 | ||
1650 | 3) x OR (!x AND y) is equivalent to x OR y. */ | |
34f97b94 XDL |
1651 | |
1652 | static bool | |
927734cf | 1653 | simplify_preds_3 (pred_chain_union *preds) |
34f97b94 | 1654 | { |
927734cf XDL |
1655 | size_t i, j, n; |
1656 | bool simplified = false; | |
34f97b94 | 1657 | |
927734cf XDL |
1658 | /* Now iteratively simplify X OR (!X AND Z ..) |
1659 | into X OR (Z ...). */ | |
34f97b94 | 1660 | |
927734cf XDL |
1661 | n = preds->length (); |
1662 | if (n < 2) | |
1663 | return false; | |
1664 | ||
1665 | for (i = 0; i < n; i++) | |
34f97b94 | 1666 | { |
927734cf XDL |
1667 | pred_info x; |
1668 | pred_chain *a_chain = &(*preds)[i]; | |
1669 | ||
1670 | if (a_chain->length () != 1) | |
1671 | continue; | |
1672 | ||
1673 | x = (*a_chain)[0]; | |
1674 | ||
1675 | for (j = 0; j < n; j++) | |
34f97b94 | 1676 | { |
927734cf XDL |
1677 | pred_chain *b_chain; |
1678 | pred_info x2; | |
1679 | size_t k; | |
1680 | ||
1681 | if (j == i) | |
1682 | continue; | |
1683 | ||
1684 | b_chain = &(*preds)[j]; | |
1685 | if (b_chain->length () < 2) | |
1686 | continue; | |
1687 | ||
1688 | for (k = 0; k < b_chain->length (); k++) | |
34f97b94 | 1689 | { |
927734cf XDL |
1690 | x2 = (*b_chain)[k]; |
1691 | if (pred_neg_p (x, x2)) | |
1692 | { | |
1693 | b_chain->unordered_remove (k); | |
1694 | simplified = true; | |
1695 | break; | |
1696 | } | |
34f97b94 XDL |
1697 | } |
1698 | } | |
34f97b94 | 1699 | } |
927734cf | 1700 | return simplified; |
34f97b94 XDL |
1701 | } |
1702 | ||
927734cf XDL |
1703 | /* The helper function implements the rule 4 for the |
1704 | OR predicate PREDS. | |
1705 | ||
1706 | 2) ((x AND y) != 0) OR (x != 0 AND y != 0) is equivalent to | |
1707 | (x != 0 ANd y != 0). */ | |
34f97b94 XDL |
1708 | |
1709 | static bool | |
927734cf | 1710 | simplify_preds_4 (pred_chain_union *preds) |
34f97b94 | 1711 | { |
927734cf XDL |
1712 | size_t i, j, n; |
1713 | bool simplified = false; | |
1714 | pred_chain_union s_preds = vNULL; | |
1715 | gimple def_stmt; | |
34f97b94 | 1716 | |
927734cf | 1717 | n = preds->length (); |
34f97b94 XDL |
1718 | for (i = 0; i < n; i++) |
1719 | { | |
927734cf XDL |
1720 | pred_info z; |
1721 | pred_chain *a_chain = &(*preds)[i]; | |
1722 | ||
1723 | if (a_chain->length () != 1) | |
1724 | continue; | |
1725 | ||
1726 | z = (*a_chain)[0]; | |
1727 | ||
1728 | if (!is_neq_zero_form_p (z)) | |
1729 | continue; | |
1730 | ||
1731 | def_stmt = SSA_NAME_DEF_STMT (z.pred_lhs); | |
1732 | if (gimple_code (def_stmt) != GIMPLE_ASSIGN) | |
1733 | continue; | |
1734 | ||
1735 | if (gimple_assign_rhs_code (def_stmt) != BIT_AND_EXPR) | |
1736 | continue; | |
1737 | ||
1738 | for (j = 0; j < n; j++) | |
1739 | { | |
1740 | pred_chain *b_chain; | |
1741 | pred_info x2, y2; | |
1742 | ||
1743 | if (j == i) | |
1744 | continue; | |
1745 | ||
1746 | b_chain = &(*preds)[j]; | |
1747 | if (b_chain->length () != 2) | |
1748 | continue; | |
1749 | ||
1750 | x2 = (*b_chain)[0]; | |
1751 | y2 = (*b_chain)[1]; | |
1752 | if (!is_neq_zero_form_p (x2) | |
1753 | || !is_neq_zero_form_p (y2)) | |
1754 | continue; | |
1755 | ||
1756 | if ((pred_expr_equal_p (x2, gimple_assign_rhs1 (def_stmt)) | |
1757 | && pred_expr_equal_p (y2, gimple_assign_rhs2 (def_stmt))) | |
1758 | || (pred_expr_equal_p (x2, gimple_assign_rhs2 (def_stmt)) | |
1759 | && pred_expr_equal_p (y2, gimple_assign_rhs1 (def_stmt)))) | |
1760 | { | |
1761 | /* Kill a_chain. */ | |
1762 | a_chain->release (); | |
1763 | simplified = true; | |
1764 | break; | |
1765 | } | |
1766 | } | |
1767 | } | |
1768 | /* Now clean up the chain. */ | |
1769 | if (simplified) | |
1770 | { | |
1771 | for (i = 0; i < n; i++) | |
1772 | { | |
1773 | if ((*preds)[i].is_empty ()) | |
1774 | continue; | |
1775 | s_preds.safe_push ((*preds)[i]); | |
1776 | } | |
1777 | preds->release (); | |
1778 | (*preds) = s_preds; | |
1779 | s_preds = vNULL; | |
34f97b94 XDL |
1780 | } |
1781 | ||
927734cf | 1782 | return simplified; |
34f97b94 XDL |
1783 | } |
1784 | ||
34f97b94 | 1785 | |
927734cf XDL |
1786 | /* This function simplifies predicates in PREDS. */ |
1787 | ||
1788 | static void | |
1789 | simplify_preds (pred_chain_union *preds, gimple use_or_def, bool is_use) | |
34f97b94 | 1790 | { |
927734cf XDL |
1791 | size_t i, n; |
1792 | bool changed = false; | |
34f97b94 | 1793 | |
927734cf | 1794 | if (dump_file && dump_flags & TDF_DETAILS) |
34f97b94 | 1795 | { |
927734cf XDL |
1796 | fprintf (dump_file, "[BEFORE SIMPLICATION -- "); |
1797 | dump_predicates (use_or_def, *preds, is_use ? "[USE]:\n" : "[DEF]:\n"); | |
34f97b94 XDL |
1798 | } |
1799 | ||
927734cf XDL |
1800 | for (i = 0; i < preds->length (); i++) |
1801 | simplify_pred (&(*preds)[i]); | |
1802 | ||
1803 | n = preds->length (); | |
1804 | if (n < 2) | |
1805 | return; | |
1806 | ||
1807 | do | |
1808 | { | |
1809 | changed = false; | |
1810 | if (simplify_preds_2 (preds)) | |
1811 | changed = true; | |
1812 | ||
1813 | /* Now iteratively simplify X OR (!X AND Z ..) | |
1814 | into X OR (Z ...). */ | |
1815 | if (simplify_preds_3 (preds)) | |
1816 | changed = true; | |
1817 | ||
1818 | if (simplify_preds_4 (preds)) | |
1819 | changed = true; | |
1820 | ||
1821 | } while (changed); | |
1822 | ||
1823 | return; | |
34f97b94 XDL |
1824 | } |
1825 | ||
927734cf XDL |
1826 | /* This is a helper function which attempts to normalize predicate chains |
1827 | by following UD chains. It basically builds up a big tree of either IOR | |
1828 | operations or AND operations, and convert the IOR tree into a | |
1829 | pred_chain_union or BIT_AND tree into a pred_chain. | |
1830 | Example: | |
56b67510 | 1831 | |
927734cf XDL |
1832 | _3 = _2 RELOP1 _1; |
1833 | _6 = _5 RELOP2 _4; | |
1834 | _9 = _8 RELOP3 _7; | |
1835 | _10 = _3 | _6; | |
1836 | _12 = _9 | _0; | |
1837 | _t = _10 | _12; | |
1838 | ||
1839 | then _t != 0 will be normalized into a pred_chain_union | |
1840 | ||
1841 | (_2 RELOP1 _1) OR (_5 RELOP2 _4) OR (_8 RELOP3 _7) OR (_0 != 0) | |
1842 | ||
1843 | Similarly given, | |
1844 | ||
1845 | _3 = _2 RELOP1 _1; | |
1846 | _6 = _5 RELOP2 _4; | |
1847 | _9 = _8 RELOP3 _7; | |
1848 | _10 = _3 & _6; | |
1849 | _12 = _9 & _0; | |
1850 | ||
1851 | then _t != 0 will be normalized into a pred_chain: | |
1852 | (_2 RELOP1 _1) AND (_5 RELOP2 _4) AND (_8 RELOP3 _7) AND (_0 != 0) | |
1853 | ||
1854 | */ | |
1855 | ||
1856 | /* This is a helper function that stores a PRED into NORM_PREDS. */ | |
1857 | ||
1858 | inline static void | |
1859 | push_pred (pred_chain_union *norm_preds, pred_info pred) | |
56b67510 | 1860 | { |
927734cf XDL |
1861 | pred_chain pred_chain = vNULL; |
1862 | pred_chain.safe_push (pred); | |
1863 | norm_preds->safe_push (pred_chain); | |
1864 | } | |
56b67510 | 1865 | |
927734cf XDL |
1866 | /* A helper function that creates a predicate of the form |
1867 | OP != 0 and push it WORK_LIST. */ | |
56b67510 | 1868 | |
927734cf | 1869 | inline static void |
ade3ff24 | 1870 | push_to_worklist (tree op, vec<pred_info, va_heap, vl_ptr> *work_list, |
6e2830c3 | 1871 | hash_set<tree> *mark_set) |
927734cf | 1872 | { |
6e2830c3 | 1873 | if (mark_set->contains (op)) |
ade3ff24 | 1874 | return; |
6e2830c3 | 1875 | mark_set->add (op); |
ade3ff24 | 1876 | |
927734cf XDL |
1877 | pred_info arg_pred; |
1878 | arg_pred.pred_lhs = op; | |
1879 | arg_pred.pred_rhs = integer_zero_node; | |
1880 | arg_pred.cond_code = NE_EXPR; | |
1881 | arg_pred.invert = false; | |
1882 | work_list->safe_push (arg_pred); | |
1883 | } | |
56b67510 | 1884 | |
927734cf XDL |
1885 | /* A helper that generates a pred_info from a gimple assignment |
1886 | CMP_ASSIGN with comparison rhs. */ | |
56b67510 | 1887 | |
927734cf XDL |
1888 | static pred_info |
1889 | get_pred_info_from_cmp (gimple cmp_assign) | |
1890 | { | |
1891 | pred_info n_pred; | |
1892 | n_pred.pred_lhs = gimple_assign_rhs1 (cmp_assign); | |
1893 | n_pred.pred_rhs = gimple_assign_rhs2 (cmp_assign); | |
1894 | n_pred.cond_code = gimple_assign_rhs_code (cmp_assign); | |
1895 | n_pred.invert = false; | |
1896 | return n_pred; | |
56b67510 XDL |
1897 | } |
1898 | ||
927734cf XDL |
1899 | /* Returns true if the PHI is a degenerated phi with |
1900 | all args with the same value (relop). In that case, *PRED | |
1901 | will be updated to that value. */ | |
56b67510 XDL |
1902 | |
1903 | static bool | |
927734cf | 1904 | is_degenerated_phi (gimple phi, pred_info *pred_p) |
56b67510 | 1905 | { |
927734cf XDL |
1906 | int i, n; |
1907 | tree op0; | |
1908 | gimple def0; | |
1909 | pred_info pred0; | |
56b67510 | 1910 | |
927734cf XDL |
1911 | n = gimple_phi_num_args (phi); |
1912 | op0 = gimple_phi_arg_def (phi, 0); | |
1913 | ||
1914 | if (TREE_CODE (op0) != SSA_NAME) | |
56b67510 XDL |
1915 | return false; |
1916 | ||
927734cf XDL |
1917 | def0 = SSA_NAME_DEF_STMT (op0); |
1918 | if (gimple_code (def0) != GIMPLE_ASSIGN) | |
1919 | return false; | |
1920 | if (TREE_CODE_CLASS (gimple_assign_rhs_code (def0)) | |
1921 | != tcc_comparison) | |
1922 | return false; | |
1923 | pred0 = get_pred_info_from_cmp (def0); | |
1924 | ||
1925 | for (i = 1; i < n; ++i) | |
56b67510 | 1926 | { |
927734cf XDL |
1927 | gimple def; |
1928 | pred_info pred; | |
1929 | tree op = gimple_phi_arg_def (phi, i); | |
1930 | ||
1931 | if (TREE_CODE (op) != SSA_NAME) | |
56b67510 XDL |
1932 | return false; |
1933 | ||
927734cf XDL |
1934 | def = SSA_NAME_DEF_STMT (op); |
1935 | if (gimple_code (def) != GIMPLE_ASSIGN) | |
1936 | return false; | |
1937 | if (TREE_CODE_CLASS (gimple_assign_rhs_code (def)) | |
1938 | != tcc_comparison) | |
1939 | return false; | |
1940 | pred = get_pred_info_from_cmp (def); | |
1941 | if (!pred_equal_p (pred, pred0)) | |
1942 | return false; | |
1943 | } | |
1944 | ||
1945 | *pred_p = pred0; | |
1946 | return true; | |
1947 | } | |
1948 | ||
1949 | /* Normalize one predicate PRED | |
1950 | 1) if PRED can no longer be normlized, put it into NORM_PREDS. | |
1951 | 2) otherwise if PRED is of the form x != 0, follow x's definition | |
1952 | and put normalized predicates into WORK_LIST. */ | |
1953 | ||
1954 | static void | |
1955 | normalize_one_pred_1 (pred_chain_union *norm_preds, | |
1956 | pred_chain *norm_chain, | |
1957 | pred_info pred, | |
1958 | enum tree_code and_or_code, | |
ade3ff24 | 1959 | vec<pred_info, va_heap, vl_ptr> *work_list, |
6e2830c3 | 1960 | hash_set<tree> *mark_set) |
927734cf XDL |
1961 | { |
1962 | if (!is_neq_zero_form_p (pred)) | |
1963 | { | |
1964 | if (and_or_code == BIT_IOR_EXPR) | |
1965 | push_pred (norm_preds, pred); | |
1966 | else | |
1967 | norm_chain->safe_push (pred); | |
1968 | return; | |
1969 | } | |
1970 | ||
1971 | gimple def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs); | |
1972 | ||
1973 | if (gimple_code (def_stmt) == GIMPLE_PHI | |
1974 | && is_degenerated_phi (def_stmt, &pred)) | |
1975 | work_list->safe_push (pred); | |
1976 | else if (gimple_code (def_stmt) == GIMPLE_PHI | |
1977 | && and_or_code == BIT_IOR_EXPR) | |
1978 | { | |
1979 | int i, n; | |
1980 | n = gimple_phi_num_args (def_stmt); | |
1981 | ||
1982 | /* If we see non zero constant, we should punt. The predicate | |
1983 | * should be one guarding the phi edge. */ | |
1984 | for (i = 0; i < n; ++i) | |
56b67510 | 1985 | { |
927734cf XDL |
1986 | tree op = gimple_phi_arg_def (def_stmt, i); |
1987 | if (TREE_CODE (op) == INTEGER_CST && !integer_zerop (op)) | |
1988 | { | |
1989 | push_pred (norm_preds, pred); | |
1990 | return; | |
1991 | } | |
56b67510 XDL |
1992 | } |
1993 | ||
927734cf XDL |
1994 | for (i = 0; i < n; ++i) |
1995 | { | |
1996 | tree op = gimple_phi_arg_def (def_stmt, i); | |
1997 | if (integer_zerop (op)) | |
1998 | continue; | |
1999 | ||
ade3ff24 | 2000 | push_to_worklist (op, work_list, mark_set); |
927734cf | 2001 | } |
ade3ff24 RH |
2002 | } |
2003 | else if (gimple_code (def_stmt) != GIMPLE_ASSIGN) | |
2004 | { | |
2005 | if (and_or_code == BIT_IOR_EXPR) | |
2006 | push_pred (norm_preds, pred); | |
2007 | else | |
2008 | norm_chain->safe_push (pred); | |
2009 | } | |
2010 | else if (gimple_assign_rhs_code (def_stmt) == and_or_code) | |
2011 | { | |
666e8e06 RB |
2012 | /* Avoid splitting up bit manipulations like x & 3 or y | 1. */ |
2013 | if (is_gimple_min_invariant (gimple_assign_rhs2 (def_stmt))) | |
2014 | { | |
2015 | /* But treat x & 3 as condition. */ | |
2016 | if (and_or_code == BIT_AND_EXPR) | |
2017 | { | |
2018 | pred_info n_pred; | |
2019 | n_pred.pred_lhs = gimple_assign_rhs1 (def_stmt); | |
2020 | n_pred.pred_rhs = gimple_assign_rhs2 (def_stmt); | |
2021 | n_pred.cond_code = and_or_code; | |
2022 | n_pred.invert = false; | |
2023 | norm_chain->safe_push (n_pred); | |
2024 | } | |
2025 | } | |
2026 | else | |
2027 | { | |
2028 | push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set); | |
2029 | push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set); | |
2030 | } | |
ade3ff24 RH |
2031 | } |
2032 | else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) | |
2033 | == tcc_comparison) | |
2034 | { | |
2035 | pred_info n_pred = get_pred_info_from_cmp (def_stmt); | |
2036 | if (and_or_code == BIT_IOR_EXPR) | |
2037 | push_pred (norm_preds, n_pred); | |
2038 | else | |
2039 | norm_chain->safe_push (n_pred); | |
2040 | } | |
2041 | else | |
2042 | { | |
2043 | if (and_or_code == BIT_IOR_EXPR) | |
2044 | push_pred (norm_preds, pred); | |
2045 | else | |
2046 | norm_chain->safe_push (pred); | |
2047 | } | |
927734cf XDL |
2048 | } |
2049 | ||
2050 | /* Normalize PRED and store the normalized predicates into NORM_PREDS. */ | |
2051 | ||
2052 | static void | |
2053 | normalize_one_pred (pred_chain_union *norm_preds, | |
2054 | pred_info pred) | |
2055 | { | |
2056 | vec<pred_info, va_heap, vl_ptr> work_list = vNULL; | |
2057 | enum tree_code and_or_code = ERROR_MARK; | |
2058 | pred_chain norm_chain = vNULL; | |
56b67510 | 2059 | |
927734cf | 2060 | if (!is_neq_zero_form_p (pred)) |
56b67510 | 2061 | { |
927734cf XDL |
2062 | push_pred (norm_preds, pred); |
2063 | return; | |
2064 | } | |
56b67510 | 2065 | |
927734cf XDL |
2066 | gimple def_stmt = SSA_NAME_DEF_STMT (pred.pred_lhs); |
2067 | if (gimple_code (def_stmt) == GIMPLE_ASSIGN) | |
2068 | and_or_code = gimple_assign_rhs_code (def_stmt); | |
2069 | if (and_or_code != BIT_IOR_EXPR | |
2070 | && and_or_code != BIT_AND_EXPR) | |
2071 | { | |
2072 | if (TREE_CODE_CLASS (and_or_code) | |
2073 | == tcc_comparison) | |
2074 | { | |
2075 | pred_info n_pred = get_pred_info_from_cmp (def_stmt); | |
2076 | push_pred (norm_preds, n_pred); | |
2077 | } | |
2078 | else | |
2079 | push_pred (norm_preds, pred); | |
2080 | return; | |
2081 | } | |
56b67510 | 2082 | |
927734cf | 2083 | work_list.safe_push (pred); |
6e2830c3 | 2084 | hash_set<tree> mark_set; |
ade3ff24 | 2085 | |
927734cf XDL |
2086 | while (!work_list.is_empty ()) |
2087 | { | |
2088 | pred_info a_pred = work_list.pop (); | |
2089 | normalize_one_pred_1 (norm_preds, &norm_chain, a_pred, | |
6e2830c3 | 2090 | and_or_code, &work_list, &mark_set); |
56b67510 | 2091 | } |
927734cf XDL |
2092 | if (and_or_code == BIT_AND_EXPR) |
2093 | norm_preds->safe_push (norm_chain); | |
2094 | ||
2095 | work_list.release (); | |
2096 | } | |
56b67510 | 2097 | |
927734cf XDL |
2098 | static void |
2099 | normalize_one_pred_chain (pred_chain_union *norm_preds, | |
2100 | pred_chain one_chain) | |
2101 | { | |
2102 | vec<pred_info, va_heap, vl_ptr> work_list = vNULL; | |
6e2830c3 | 2103 | hash_set<tree> mark_set; |
927734cf XDL |
2104 | pred_chain norm_chain = vNULL; |
2105 | size_t i; | |
2106 | ||
2107 | for (i = 0; i < one_chain.length (); i++) | |
ade3ff24 RH |
2108 | { |
2109 | work_list.safe_push (one_chain[i]); | |
6e2830c3 | 2110 | mark_set.add (one_chain[i].pred_lhs); |
ade3ff24 | 2111 | } |
927734cf XDL |
2112 | |
2113 | while (!work_list.is_empty ()) | |
56b67510 | 2114 | { |
927734cf XDL |
2115 | pred_info a_pred = work_list.pop (); |
2116 | normalize_one_pred_1 (0, &norm_chain, a_pred, | |
6e2830c3 | 2117 | BIT_AND_EXPR, &work_list, &mark_set); |
56b67510 | 2118 | } |
927734cf XDL |
2119 | |
2120 | norm_preds->safe_push (norm_chain); | |
2121 | work_list.release (); | |
56b67510 XDL |
2122 | } |
2123 | ||
927734cf XDL |
2124 | /* Normalize predicate chains PREDS and returns the normalized one. */ |
2125 | ||
2126 | static pred_chain_union | |
2127 | normalize_preds (pred_chain_union preds, gimple use_or_def, bool is_use) | |
2128 | { | |
2129 | pred_chain_union norm_preds = vNULL; | |
2130 | size_t n = preds.length (); | |
2131 | size_t i; | |
2132 | ||
2133 | if (dump_file && dump_flags & TDF_DETAILS) | |
2134 | { | |
2135 | fprintf (dump_file, "[BEFORE NORMALIZATION --"); | |
2136 | dump_predicates (use_or_def, preds, is_use ? "[USE]:\n" : "[DEF]:\n"); | |
2137 | } | |
2138 | ||
2139 | for (i = 0; i < n; i++) | |
2140 | { | |
2141 | if (preds[i].length () != 1) | |
2142 | normalize_one_pred_chain (&norm_preds, preds[i]); | |
2143 | else | |
2144 | { | |
2145 | normalize_one_pred (&norm_preds, preds[i][0]); | |
2146 | preds[i].release (); | |
2147 | } | |
2148 | } | |
2149 | ||
2150 | if (dump_file) | |
2151 | { | |
2152 | fprintf (dump_file, "[AFTER NORMALIZATION -- "); | |
2153 | dump_predicates (use_or_def, norm_preds, is_use ? "[USE]:\n" : "[DEF]:\n"); | |
2154 | } | |
2155 | ||
2156 | preds.release (); | |
2157 | return norm_preds; | |
2158 | } | |
56b67510 XDL |
2159 | |
2160 | ||
34f97b94 XDL |
2161 | /* Computes the predicates that guard the use and checks |
2162 | if the incoming paths that have empty (or possibly | |
073a8998 | 2163 | empty) definition can be pruned/filtered. The function returns |
34f97b94 XDL |
2164 | true if it can be determined that the use of PHI's def in |
2165 | USE_STMT is guarded with a predicate set not overlapping with | |
2166 | predicate sets of all runtime paths that do not have a definition. | |
c0503346 | 2167 | |
34f97b94 XDL |
2168 | Returns false if it is not or it can not be determined. USE_BB is |
2169 | the bb of the use (for phi operand use, the bb is not the bb of | |
c0503346 PP |
2170 | the phi stmt, but the src bb of the operand edge). |
2171 | ||
2172 | UNINIT_OPNDS is a bit vector. If an operand of PHI is uninitialized, the | |
2173 | corresponding bit in the vector is 1. VISITED_PHIS is a pointer | |
2174 | set of phis being visited. | |
2175 | ||
2176 | *DEF_PREDS contains the (memoized) defining predicate chains of PHI. | |
2177 | If *DEF_PREDS is the empty vector, the defining predicate chains of | |
2178 | PHI will be computed and stored into *DEF_PREDS as needed. | |
2179 | ||
2180 | VISITED_PHIS is a pointer set of phis being visited. */ | |
34f97b94 XDL |
2181 | |
2182 | static bool | |
2183 | is_use_properly_guarded (gimple use_stmt, | |
2184 | basic_block use_bb, | |
538dd0b7 | 2185 | gphi *phi, |
34f97b94 | 2186 | unsigned uninit_opnds, |
c0503346 | 2187 | pred_chain_union *def_preds, |
538dd0b7 | 2188 | hash_set<gphi *> *visited_phis) |
34f97b94 XDL |
2189 | { |
2190 | basic_block phi_bb; | |
927734cf | 2191 | pred_chain_union preds = vNULL; |
34f97b94 XDL |
2192 | bool has_valid_preds = false; |
2193 | bool is_properly_guarded = false; | |
2194 | ||
6e2830c3 | 2195 | if (visited_phis->add (phi)) |
34f97b94 XDL |
2196 | return false; |
2197 | ||
2198 | phi_bb = gimple_bb (phi); | |
2199 | ||
2200 | if (is_non_loop_exit_postdominating (use_bb, phi_bb)) | |
2201 | return false; | |
2202 | ||
927734cf | 2203 | has_valid_preds = find_predicates (&preds, phi_bb, use_bb); |
34f97b94 XDL |
2204 | |
2205 | if (!has_valid_preds) | |
2206 | { | |
927734cf | 2207 | destroy_predicate_vecs (preds); |
34f97b94 XDL |
2208 | return false; |
2209 | } | |
2210 | ||
927734cf XDL |
2211 | /* Try to prune the dead incoming phi edges. */ |
2212 | is_properly_guarded | |
2213 | = use_pred_not_overlap_with_undef_path_pred (preds, phi, uninit_opnds, | |
2214 | visited_phis); | |
34f97b94 | 2215 | |
927734cf | 2216 | if (is_properly_guarded) |
34f97b94 | 2217 | { |
927734cf XDL |
2218 | destroy_predicate_vecs (preds); |
2219 | return true; | |
2220 | } | |
56b67510 | 2221 | |
c0503346 | 2222 | if (def_preds->is_empty ()) |
927734cf | 2223 | { |
c0503346 PP |
2224 | has_valid_preds = find_def_preds (def_preds, phi); |
2225 | ||
2226 | if (!has_valid_preds) | |
2227 | { | |
2228 | destroy_predicate_vecs (preds); | |
2229 | return false; | |
2230 | } | |
2231 | ||
2232 | simplify_preds (def_preds, phi, false); | |
2233 | *def_preds = normalize_preds (*def_preds, phi, false); | |
34f97b94 XDL |
2234 | } |
2235 | ||
927734cf XDL |
2236 | simplify_preds (&preds, use_stmt, true); |
2237 | preds = normalize_preds (preds, use_stmt, true); | |
2238 | ||
c0503346 | 2239 | is_properly_guarded = is_superset_of (*def_preds, preds); |
34f97b94 | 2240 | |
927734cf | 2241 | destroy_predicate_vecs (preds); |
34f97b94 XDL |
2242 | return is_properly_guarded; |
2243 | } | |
2244 | ||
2245 | /* Searches through all uses of a potentially | |
2246 | uninitialized variable defined by PHI and returns a use | |
2247 | statement if the use is not properly guarded. It returns | |
2248 | NULL if all uses are guarded. UNINIT_OPNDS is a bitvector | |
2249 | holding the position(s) of uninit PHI operands. WORKLIST | |
2250 | is the vector of candidate phis that may be updated by this | |
2251 | function. ADDED_TO_WORKLIST is the pointer set tracking | |
2252 | if the new phi is already in the worklist. */ | |
2253 | ||
2254 | static gimple | |
538dd0b7 DM |
2255 | find_uninit_use (gphi *phi, unsigned uninit_opnds, |
2256 | vec<gphi *> *worklist, | |
2257 | hash_set<gphi *> *added_to_worklist) | |
34f97b94 XDL |
2258 | { |
2259 | tree phi_result; | |
2260 | use_operand_p use_p; | |
2261 | gimple use_stmt; | |
2262 | imm_use_iterator iter; | |
c0503346 PP |
2263 | pred_chain_union def_preds = vNULL; |
2264 | gimple ret = NULL; | |
34f97b94 XDL |
2265 | |
2266 | phi_result = gimple_phi_result (phi); | |
2267 | ||
2268 | FOR_EACH_IMM_USE_FAST (use_p, iter, phi_result) | |
2269 | { | |
34f97b94 XDL |
2270 | basic_block use_bb; |
2271 | ||
480161b5 RG |
2272 | use_stmt = USE_STMT (use_p); |
2273 | if (is_gimple_debug (use_stmt)) | |
2274 | continue; | |
34f97b94 | 2275 | |
538dd0b7 DM |
2276 | if (gphi *use_phi = dyn_cast <gphi *> (use_stmt)) |
2277 | use_bb = gimple_phi_arg_edge (use_phi, | |
480161b5 RG |
2278 | PHI_ARG_INDEX_FROM_USE (use_p))->src; |
2279 | else | |
2280 | use_bb = gimple_bb (use_stmt); | |
34f97b94 | 2281 | |
538dd0b7 | 2282 | hash_set<gphi *> visited_phis; |
927734cf | 2283 | if (is_use_properly_guarded (use_stmt, use_bb, phi, uninit_opnds, |
c0503346 | 2284 | &def_preds, &visited_phis)) |
6e2830c3 | 2285 | continue; |
34f97b94 | 2286 | |
e74780a3 XDL |
2287 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2288 | { | |
2289 | fprintf (dump_file, "[CHECK]: Found unguarded use: "); | |
2290 | print_gimple_stmt (dump_file, use_stmt, 0, 0); | |
2291 | } | |
34f97b94 XDL |
2292 | /* Found one real use, return. */ |
2293 | if (gimple_code (use_stmt) != GIMPLE_PHI) | |
c0503346 PP |
2294 | { |
2295 | ret = use_stmt; | |
2296 | break; | |
2297 | } | |
34f97b94 XDL |
2298 | |
2299 | /* Found a phi use that is not guarded, | |
2300 | add the phi to the worklist. */ | |
538dd0b7 | 2301 | if (!added_to_worklist->add (as_a <gphi *> (use_stmt))) |
34f97b94 | 2302 | { |
e74780a3 XDL |
2303 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2304 | { | |
2305 | fprintf (dump_file, "[WORKLIST]: Update worklist with phi: "); | |
2306 | print_gimple_stmt (dump_file, use_stmt, 0, 0); | |
2307 | } | |
2308 | ||
538dd0b7 | 2309 | worklist->safe_push (as_a <gphi *> (use_stmt)); |
6e2830c3 | 2310 | possibly_undefined_names->add (phi_result); |
34f97b94 XDL |
2311 | } |
2312 | } | |
2313 | ||
c0503346 PP |
2314 | destroy_predicate_vecs (def_preds); |
2315 | return ret; | |
34f97b94 XDL |
2316 | } |
2317 | ||
2318 | /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions | |
2319 | and gives warning if there exists a runtime path from the entry to a | |
2320 | use of the PHI def that does not contain a definition. In other words, | |
2321 | the warning is on the real use. The more dead paths that can be pruned | |
2322 | by the compiler, the fewer false positives the warning is. WORKLIST | |
2323 | is a vector of candidate phis to be examined. ADDED_TO_WORKLIST is | |
2324 | a pointer set tracking if the new phi is added to the worklist or not. */ | |
2325 | ||
2326 | static void | |
538dd0b7 DM |
2327 | warn_uninitialized_phi (gphi *phi, vec<gphi *> *worklist, |
2328 | hash_set<gphi *> *added_to_worklist) | |
34f97b94 XDL |
2329 | { |
2330 | unsigned uninit_opnds; | |
2331 | gimple uninit_use_stmt = 0; | |
2332 | tree uninit_op; | |
e1ec47c4 TP |
2333 | int phiarg_index; |
2334 | location_t loc; | |
34f97b94 | 2335 | |
ea057359 RG |
2336 | /* Don't look at virtual operands. */ |
2337 | if (virtual_operand_p (gimple_phi_result (phi))) | |
34f97b94 XDL |
2338 | return; |
2339 | ||
2340 | uninit_opnds = compute_uninit_opnds_pos (phi); | |
2341 | ||
2342 | if (MASK_EMPTY (uninit_opnds)) | |
2343 | return; | |
2344 | ||
e74780a3 XDL |
2345 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2346 | { | |
2347 | fprintf (dump_file, "[CHECK]: examining phi: "); | |
2348 | print_gimple_stmt (dump_file, phi, 0, 0); | |
2349 | } | |
2350 | ||
34f97b94 XDL |
2351 | /* Now check if we have any use of the value without proper guard. */ |
2352 | uninit_use_stmt = find_uninit_use (phi, uninit_opnds, | |
2353 | worklist, added_to_worklist); | |
2354 | ||
2355 | /* All uses are properly guarded. */ | |
2356 | if (!uninit_use_stmt) | |
2357 | return; | |
2358 | ||
e1ec47c4 TP |
2359 | phiarg_index = MASK_FIRST_SET_BIT (uninit_opnds); |
2360 | uninit_op = gimple_phi_arg_def (phi, phiarg_index); | |
70b5e7dc RG |
2361 | if (SSA_NAME_VAR (uninit_op) == NULL_TREE) |
2362 | return; | |
e1ec47c4 TP |
2363 | if (gimple_phi_arg_has_location (phi, phiarg_index)) |
2364 | loc = gimple_phi_arg_location (phi, phiarg_index); | |
2365 | else | |
2366 | loc = UNKNOWN_LOCATION; | |
8d2b0410 RG |
2367 | warn_uninit (OPT_Wmaybe_uninitialized, uninit_op, SSA_NAME_VAR (uninit_op), |
2368 | SSA_NAME_VAR (uninit_op), | |
34f97b94 | 2369 | "%qD may be used uninitialized in this function", |
e1ec47c4 | 2370 | uninit_use_stmt, loc); |
34f97b94 XDL |
2371 | |
2372 | } | |
2373 | ||
be55bfe6 TS |
2374 | static bool |
2375 | gate_warn_uninitialized (void) | |
2376 | { | |
2377 | return warn_uninitialized || warn_maybe_uninitialized; | |
2378 | } | |
34f97b94 | 2379 | |
be55bfe6 | 2380 | namespace { |
34f97b94 | 2381 | |
be55bfe6 TS |
2382 | const pass_data pass_data_late_warn_uninitialized = |
2383 | { | |
2384 | GIMPLE_PASS, /* type */ | |
2385 | "uninit", /* name */ | |
2386 | OPTGROUP_NONE, /* optinfo_flags */ | |
be55bfe6 TS |
2387 | TV_NONE, /* tv_id */ |
2388 | PROP_ssa, /* properties_required */ | |
2389 | 0, /* properties_provided */ | |
2390 | 0, /* properties_destroyed */ | |
2391 | 0, /* todo_flags_start */ | |
2392 | 0, /* todo_flags_finish */ | |
2393 | }; | |
2394 | ||
2395 | class pass_late_warn_uninitialized : public gimple_opt_pass | |
2396 | { | |
2397 | public: | |
2398 | pass_late_warn_uninitialized (gcc::context *ctxt) | |
2399 | : gimple_opt_pass (pass_data_late_warn_uninitialized, ctxt) | |
2400 | {} | |
2401 | ||
2402 | /* opt_pass methods: */ | |
2403 | opt_pass * clone () { return new pass_late_warn_uninitialized (m_ctxt); } | |
2404 | virtual bool gate (function *) { return gate_warn_uninitialized (); } | |
2405 | virtual unsigned int execute (function *); | |
2406 | ||
2407 | }; // class pass_late_warn_uninitialized | |
2408 | ||
2409 | unsigned int | |
2410 | pass_late_warn_uninitialized::execute (function *fun) | |
34f97b94 XDL |
2411 | { |
2412 | basic_block bb; | |
538dd0b7 DM |
2413 | gphi_iterator gsi; |
2414 | vec<gphi *> worklist = vNULL; | |
34f97b94 XDL |
2415 | |
2416 | calculate_dominance_info (CDI_DOMINATORS); | |
2417 | calculate_dominance_info (CDI_POST_DOMINATORS); | |
2418 | /* Re-do the plain uninitialized variable check, as optimization may have | |
2419 | straightened control flow. Do this first so that we don't accidentally | |
2420 | get a "may be" warning when we'd have seen an "is" warning later. */ | |
2421 | warn_uninitialized_vars (/*warn_possibly_uninitialized=*/1); | |
2422 | ||
2423 | timevar_push (TV_TREE_UNINIT); | |
2424 | ||
6e2830c3 | 2425 | possibly_undefined_names = new hash_set<tree>; |
538dd0b7 | 2426 | hash_set<gphi *> added_to_worklist; |
34f97b94 XDL |
2427 | |
2428 | /* Initialize worklist */ | |
be55bfe6 | 2429 | FOR_EACH_BB_FN (bb, fun) |
34f97b94 XDL |
2430 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
2431 | { | |
538dd0b7 | 2432 | gphi *phi = gsi.phi (); |
be55bfe6 TS |
2433 | size_t n, i; |
2434 | ||
2435 | n = gimple_phi_num_args (phi); | |
2436 | ||
2437 | /* Don't look at virtual operands. */ | |
2438 | if (virtual_operand_p (gimple_phi_result (phi))) | |
2439 | continue; | |
2440 | ||
2441 | for (i = 0; i < n; ++i) | |
2442 | { | |
2443 | tree op = gimple_phi_arg_def (phi, i); | |
2444 | if (TREE_CODE (op) == SSA_NAME | |
2445 | && uninit_undefined_value_p (op)) | |
2446 | { | |
2447 | worklist.safe_push (phi); | |
6e2830c3 | 2448 | added_to_worklist.add (phi); |
be55bfe6 TS |
2449 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2450 | { | |
2451 | fprintf (dump_file, "[WORKLIST]: add to initial list: "); | |
2452 | print_gimple_stmt (dump_file, phi, 0, 0); | |
2453 | } | |
2454 | break; | |
2455 | } | |
2456 | } | |
34f97b94 XDL |
2457 | } |
2458 | ||
9771b263 | 2459 | while (worklist.length () != 0) |
34f97b94 | 2460 | { |
538dd0b7 | 2461 | gphi *cur_phi = 0; |
9771b263 | 2462 | cur_phi = worklist.pop (); |
6e2830c3 | 2463 | warn_uninitialized_phi (cur_phi, &worklist, &added_to_worklist); |
34f97b94 | 2464 | } |
e74780a3 | 2465 | |
9771b263 | 2466 | worklist.release (); |
6e2830c3 | 2467 | delete possibly_undefined_names; |
34f97b94 XDL |
2468 | possibly_undefined_names = NULL; |
2469 | free_dominance_info (CDI_POST_DOMINATORS); | |
2470 | timevar_pop (TV_TREE_UNINIT); | |
2471 | return 0; | |
2472 | } | |
2473 | ||
27a4cd48 DM |
2474 | } // anon namespace |
2475 | ||
2476 | gimple_opt_pass * | |
2477 | make_pass_late_warn_uninitialized (gcc::context *ctxt) | |
2478 | { | |
2479 | return new pass_late_warn_uninitialized (ctxt); | |
2480 | } | |
c152901f AM |
2481 | |
2482 | ||
2483 | static unsigned int | |
2484 | execute_early_warn_uninitialized (void) | |
2485 | { | |
2486 | /* Currently, this pass runs always but | |
2487 | execute_late_warn_uninitialized only runs with optimization. With | |
2488 | optimization we want to warn about possible uninitialized as late | |
2489 | as possible, thus don't do it here. However, without | |
927734cf | 2490 | optimization we need to warn here about "may be uninitialized". */ |
c152901f AM |
2491 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2492 | ||
2493 | warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize); | |
2494 | ||
2495 | /* Post-dominator information can not be reliably updated. Free it | |
2496 | after the use. */ | |
2497 | ||
2498 | free_dominance_info (CDI_POST_DOMINATORS); | |
2499 | return 0; | |
2500 | } | |
2501 | ||
2502 | ||
2503 | namespace { | |
2504 | ||
2505 | const pass_data pass_data_early_warn_uninitialized = | |
2506 | { | |
2507 | GIMPLE_PASS, /* type */ | |
2508 | "*early_warn_uninitialized", /* name */ | |
2509 | OPTGROUP_NONE, /* optinfo_flags */ | |
c152901f AM |
2510 | TV_TREE_UNINIT, /* tv_id */ |
2511 | PROP_ssa, /* properties_required */ | |
2512 | 0, /* properties_provided */ | |
2513 | 0, /* properties_destroyed */ | |
2514 | 0, /* todo_flags_start */ | |
2515 | 0, /* todo_flags_finish */ | |
2516 | }; | |
2517 | ||
2518 | class pass_early_warn_uninitialized : public gimple_opt_pass | |
2519 | { | |
2520 | public: | |
c3284718 RS |
2521 | pass_early_warn_uninitialized (gcc::context *ctxt) |
2522 | : gimple_opt_pass (pass_data_early_warn_uninitialized, ctxt) | |
c152901f AM |
2523 | {} |
2524 | ||
2525 | /* opt_pass methods: */ | |
1a3d085c | 2526 | virtual bool gate (function *) { return gate_warn_uninitialized (); } |
be55bfe6 TS |
2527 | virtual unsigned int execute (function *) |
2528 | { | |
2529 | return execute_early_warn_uninitialized (); | |
2530 | } | |
c152901f AM |
2531 | |
2532 | }; // class pass_early_warn_uninitialized | |
2533 | ||
2534 | } // anon namespace | |
2535 | ||
2536 | gimple_opt_pass * | |
2537 | make_pass_early_warn_uninitialized (gcc::context *ctxt) | |
2538 | { | |
2539 | return new pass_early_warn_uninitialized (ctxt); | |
2540 | } |