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95bb87b2 | 1 | /* Harden conditionals. |
7adcbafe | 2 | Copyright (C) 2021-2022 Free Software Foundation, Inc. |
95bb87b2 AO |
3 | Contributed by Alexandre Oliva <oliva@adacore.com>. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | 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" | |
24 | #include "backend.h" | |
0485ce91 AO |
25 | #include "target.h" |
26 | #include "rtl.h" | |
95bb87b2 AO |
27 | #include "tree.h" |
28 | #include "fold-const.h" | |
29 | #include "gimple.h" | |
30 | #include "gimplify.h" | |
31 | #include "tree-pass.h" | |
32 | #include "ssa.h" | |
33 | #include "gimple-iterator.h" | |
34 | #include "tree-cfg.h" | |
35 | #include "basic-block.h" | |
36 | #include "cfghooks.h" | |
37 | #include "cfgloop.h" | |
2bff91f3 | 38 | #include "tree-eh.h" |
95bb87b2 AO |
39 | #include "diagnostic.h" |
40 | #include "intl.h" | |
41 | ||
42 | namespace { | |
43 | ||
44 | /* These passes introduces redundant, but reversed conditionals at | |
45 | compares, such as those used in conditional branches, and those | |
46 | that compute boolean results. This doesn't make much sense for | |
47 | abstract CPUs, but this kind of hardening may avoid undesirable | |
48 | execution paths on actual CPUs under such attacks as of power | |
49 | deprivation. */ | |
50 | ||
51 | /* Define a pass to harden conditionals other than branches. */ | |
52 | ||
53 | const pass_data pass_data_harden_compares = { | |
54 | GIMPLE_PASS, | |
55 | "hardcmp", | |
56 | OPTGROUP_NONE, | |
57 | TV_NONE, | |
58 | PROP_cfg | PROP_ssa, // properties_required | |
59 | 0, // properties_provided | |
60 | 0, // properties_destroyed | |
61 | 0, // properties_start | |
62 | TODO_update_ssa | |
63 | | TODO_cleanup_cfg | |
64 | | TODO_verify_il, // properties_finish | |
65 | }; | |
66 | ||
67 | class pass_harden_compares : public gimple_opt_pass | |
68 | { | |
69 | public: | |
70 | pass_harden_compares (gcc::context *ctxt) | |
71 | : gimple_opt_pass (pass_data_harden_compares, ctxt) | |
72 | {} | |
73 | opt_pass *clone () { return new pass_harden_compares (m_ctxt); } | |
74 | virtual bool gate (function *) { | |
75 | return flag_harden_compares; | |
76 | } | |
77 | virtual unsigned int execute (function *); | |
78 | }; | |
79 | ||
80 | /* Define a pass to harden conditionals in branches. This pass must | |
81 | run after the above, otherwise it will re-harden the checks | |
82 | introduced by the above. */ | |
83 | ||
84 | const pass_data pass_data_harden_conditional_branches = { | |
85 | GIMPLE_PASS, | |
86 | "hardcbr", | |
87 | OPTGROUP_NONE, | |
88 | TV_NONE, | |
89 | PROP_cfg | PROP_ssa, // properties_required | |
90 | 0, // properties_provided | |
91 | 0, // properties_destroyed | |
92 | 0, // properties_start | |
93 | TODO_update_ssa | |
94 | | TODO_cleanup_cfg | |
95 | | TODO_verify_il, // properties_finish | |
96 | }; | |
97 | ||
98 | class pass_harden_conditional_branches : public gimple_opt_pass | |
99 | { | |
100 | public: | |
101 | pass_harden_conditional_branches (gcc::context *ctxt) | |
102 | : gimple_opt_pass (pass_data_harden_conditional_branches, ctxt) | |
103 | {} | |
104 | opt_pass *clone () { return new pass_harden_conditional_branches (m_ctxt); } | |
105 | virtual bool gate (function *) { | |
106 | return flag_harden_conditional_branches; | |
107 | } | |
108 | virtual unsigned int execute (function *); | |
109 | }; | |
110 | ||
111 | } | |
112 | ||
113 | /* If VAL is an SSA name, return an SSA name holding the same value, | |
114 | but without the compiler's knowing that it holds the same value, so | |
115 | that uses thereof can't be optimized the way VAL might. Insert | |
116 | stmts that initialize it before *GSIP, with LOC. | |
117 | ||
118 | Otherwise, VAL must be an invariant, returned unchanged. */ | |
119 | ||
120 | static inline tree | |
121 | detach_value (location_t loc, gimple_stmt_iterator *gsip, tree val) | |
122 | { | |
123 | if (TREE_CONSTANT (val) || TREE_CODE (val) != SSA_NAME) | |
124 | { | |
125 | gcc_checking_assert (is_gimple_min_invariant (val)); | |
126 | return val; | |
127 | } | |
128 | ||
fb488cba AO |
129 | /* Create a SSA "copy" of VAL. It would be nice to have it named |
130 | after the corresponding variable, but sharing the same decl is | |
131 | problematic when VAL is a DECL_BY_REFERENCE RESULT_DECL, and | |
132 | copying just the identifier hits -fcompare-debug failures. */ | |
38e4a361 | 133 | tree ret = make_ssa_name (TREE_TYPE (val)); |
95bb87b2 | 134 | |
0485ce91 AO |
135 | /* Some modes won't fit in general regs, so we fall back to memory |
136 | for them. ??? It would be ideal to try to identify an alternate, | |
137 | wider or more suitable register class, and use the corresponding | |
138 | constraint, but there's no logic to go from register class to | |
139 | constraint, even if there is a corresponding constraint, and even | |
140 | if we could enumerate constraints, we can't get to their string | |
141 | either. So this will do for now. */ | |
142 | bool need_memory = true; | |
143 | enum machine_mode mode = TYPE_MODE (TREE_TYPE (val)); | |
144 | if (mode != BLKmode) | |
145 | for (int i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
146 | if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i) | |
147 | && targetm.hard_regno_mode_ok (i, mode)) | |
148 | { | |
149 | need_memory = false; | |
150 | break; | |
151 | } | |
152 | ||
153 | tree asminput = val; | |
154 | tree asmoutput = ret; | |
155 | const char *constraint_out = need_memory ? "=m" : "=g"; | |
156 | const char *constraint_in = need_memory ? "m" : "0"; | |
157 | ||
158 | if (need_memory) | |
159 | { | |
160 | tree temp = create_tmp_var (TREE_TYPE (val), "dtch"); | |
161 | mark_addressable (temp); | |
162 | ||
163 | gassign *copyin = gimple_build_assign (temp, asminput); | |
164 | gimple_set_location (copyin, loc); | |
165 | gsi_insert_before (gsip, copyin, GSI_SAME_STMT); | |
166 | ||
167 | asminput = asmoutput = temp; | |
168 | } | |
169 | ||
170 | /* Output an asm statement with matching input and output. It does | |
171 | nothing, but after it the compiler no longer knows the output | |
172 | still holds the same value as the input. */ | |
95bb87b2 AO |
173 | vec<tree, va_gc> *inputs = NULL; |
174 | vec<tree, va_gc> *outputs = NULL; | |
175 | vec_safe_push (outputs, | |
176 | build_tree_list | |
177 | (build_tree_list | |
0485ce91 AO |
178 | (NULL_TREE, build_string (strlen (constraint_out), |
179 | constraint_out)), | |
180 | asmoutput)); | |
95bb87b2 AO |
181 | vec_safe_push (inputs, |
182 | build_tree_list | |
183 | (build_tree_list | |
0485ce91 AO |
184 | (NULL_TREE, build_string (strlen (constraint_in), |
185 | constraint_in)), | |
186 | asminput)); | |
95bb87b2 AO |
187 | gasm *detach = gimple_build_asm_vec ("", inputs, outputs, |
188 | NULL, NULL); | |
189 | gimple_set_location (detach, loc); | |
190 | gsi_insert_before (gsip, detach, GSI_SAME_STMT); | |
191 | ||
0485ce91 AO |
192 | if (need_memory) |
193 | { | |
194 | gassign *copyout = gimple_build_assign (ret, asmoutput); | |
195 | gimple_set_location (copyout, loc); | |
196 | gsi_insert_before (gsip, copyout, GSI_SAME_STMT); | |
197 | SSA_NAME_DEF_STMT (ret) = copyout; | |
198 | ||
199 | gassign *clobber = gimple_build_assign (asmoutput, | |
200 | build_clobber | |
201 | (TREE_TYPE (asmoutput))); | |
202 | gimple_set_location (clobber, loc); | |
203 | gsi_insert_before (gsip, clobber, GSI_SAME_STMT); | |
204 | } | |
205 | else | |
206 | SSA_NAME_DEF_STMT (ret) = detach; | |
95bb87b2 AO |
207 | |
208 | return ret; | |
209 | } | |
210 | ||
211 | /* Build a cond stmt out of COP, LHS, RHS, insert it before *GSIP with | |
212 | location LOC. *GSIP must be at the end of a basic block. The succ | |
213 | edge out of the block becomes the true or false edge opposite to | |
214 | that in FLAGS. Create a new block with a single trap stmt, in the | |
215 | cold partition if the function is partitioned,, and a new edge to | |
216 | it as the other edge for the cond. */ | |
217 | ||
218 | static inline void | |
219 | insert_check_and_trap (location_t loc, gimple_stmt_iterator *gsip, | |
220 | int flags, enum tree_code cop, tree lhs, tree rhs) | |
221 | { | |
222 | basic_block chk = gsi_bb (*gsip); | |
223 | ||
224 | gcond *cond = gimple_build_cond (cop, lhs, rhs, NULL, NULL); | |
225 | gimple_set_location (cond, loc); | |
226 | gsi_insert_before (gsip, cond, GSI_SAME_STMT); | |
227 | ||
228 | basic_block trp = create_empty_bb (chk); | |
229 | ||
230 | gimple_stmt_iterator gsit = gsi_after_labels (trp); | |
231 | gcall *trap = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0); | |
232 | gimple_set_location (trap, loc); | |
233 | gsi_insert_before (&gsit, trap, GSI_SAME_STMT); | |
234 | ||
235 | if (dump_file) | |
236 | fprintf (dump_file, | |
237 | "Adding reversed compare to block %i, and trap to block %i\n", | |
238 | chk->index, trp->index); | |
239 | ||
240 | if (BB_PARTITION (chk)) | |
241 | BB_SET_PARTITION (trp, BB_COLD_PARTITION); | |
242 | ||
243 | int true_false_flag = flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
244 | gcc_assert (true_false_flag); | |
245 | int neg_true_false_flag = (~flags) & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
246 | ||
247 | /* Remove the fallthru bit, and set the truth value for the | |
248 | preexisting edge and for the newly-created one. In hardcbr, | |
249 | FLAGS is taken from the edge of the original cond expr that we're | |
250 | dealing with, so the reversed compare is expected to yield the | |
251 | negated result, and the same result calls for a trap. In | |
252 | hardcmp, we're comparing the boolean results of the original and | |
253 | of the reversed compare, so we're passed FLAGS to trap on | |
254 | equality. */ | |
255 | single_succ_edge (chk)->flags &= ~EDGE_FALLTHRU; | |
256 | single_succ_edge (chk)->flags |= neg_true_false_flag; | |
257 | edge e = make_edge (chk, trp, true_false_flag); | |
258 | e->goto_locus = loc; | |
259 | ||
260 | if (dom_info_available_p (CDI_DOMINATORS)) | |
261 | set_immediate_dominator (CDI_DOMINATORS, trp, chk); | |
262 | if (current_loops) | |
263 | add_bb_to_loop (trp, current_loops->tree_root); | |
264 | } | |
265 | ||
266 | /* Split edge E, and insert_check_and_trap (see above) in the | |
267 | newly-created block, using detached copies of LHS's and RHS's | |
268 | values (see detach_value above) for the COP compare. */ | |
269 | ||
270 | static inline void | |
271 | insert_edge_check_and_trap (location_t loc, edge e, | |
272 | enum tree_code cop, tree lhs, tree rhs) | |
273 | { | |
274 | int flags = e->flags; | |
275 | basic_block src = e->src; | |
276 | basic_block dest = e->dest; | |
277 | location_t eloc = e->goto_locus; | |
278 | ||
279 | basic_block chk = split_edge (e); | |
280 | e = NULL; | |
281 | ||
282 | single_pred_edge (chk)->goto_locus = loc; | |
283 | single_succ_edge (chk)->goto_locus = eloc; | |
284 | ||
285 | if (dump_file) | |
286 | fprintf (dump_file, | |
287 | "Splitting edge %i->%i into block %i\n", | |
288 | src->index, dest->index, chk->index); | |
289 | ||
290 | gimple_stmt_iterator gsik = gsi_after_labels (chk); | |
291 | ||
292 | bool same_p = (lhs == rhs); | |
293 | lhs = detach_value (loc, &gsik, lhs); | |
294 | rhs = same_p ? lhs : detach_value (loc, &gsik, rhs); | |
295 | ||
296 | insert_check_and_trap (loc, &gsik, flags, cop, lhs, rhs); | |
297 | } | |
298 | ||
299 | /* Harden cond stmts at the end of FUN's blocks. */ | |
300 | ||
301 | unsigned int | |
302 | pass_harden_conditional_branches::execute (function *fun) | |
303 | { | |
304 | basic_block bb; | |
305 | FOR_EACH_BB_REVERSE_FN (bb, fun) | |
306 | { | |
307 | gimple_stmt_iterator gsi = gsi_last_bb (bb); | |
308 | ||
309 | if (gsi_end_p (gsi)) | |
310 | continue; | |
311 | ||
312 | gcond *cond = dyn_cast <gcond *> (gsi_stmt (gsi)); | |
313 | if (!cond) | |
314 | continue; | |
315 | ||
316 | /* Turn: | |
317 | ||
318 | if (x op y) goto l1; else goto l2; | |
319 | ||
320 | into: | |
321 | ||
322 | if (x op y) goto l1'; else goto l2'; | |
323 | l1': if (x' cop y') goto l1'trap; else goto l1; | |
324 | l1'trap: __builtin_trap (); | |
325 | l2': if (x' cop y') goto l2; else goto l2'trap; | |
326 | l2'trap: __builtin_trap (); | |
327 | ||
328 | where cop is a complementary boolean operation to op; l1', l1'trap, | |
329 | l2' and l2'trap are newly-created labels; and x' and y' hold the same | |
330 | value as x and y, but in a way that does not enable the compiler to | |
331 | optimize the redundant compare away. | |
332 | */ | |
333 | ||
334 | enum tree_code op = gimple_cond_code (cond); | |
335 | tree lhs = gimple_cond_lhs (cond); | |
336 | tree rhs = gimple_cond_rhs (cond); | |
337 | location_t loc = gimple_location (cond); | |
338 | ||
339 | enum tree_code cop = invert_tree_comparison (op, HONOR_NANS (lhs)); | |
340 | ||
341 | if (cop == ERROR_MARK) | |
342 | /* ??? Can we do better? */ | |
343 | continue; | |
344 | ||
345 | insert_edge_check_and_trap (loc, EDGE_SUCC (bb, 0), cop, lhs, rhs); | |
346 | insert_edge_check_and_trap (loc, EDGE_SUCC (bb, 1), cop, lhs, rhs); | |
347 | } | |
348 | ||
349 | return 0; | |
350 | } | |
351 | ||
352 | /* Instantiate a hardcbr pass. */ | |
353 | ||
354 | gimple_opt_pass * | |
355 | make_pass_harden_conditional_branches (gcc::context *ctxt) | |
356 | { | |
357 | return new pass_harden_conditional_branches (ctxt); | |
358 | } | |
359 | ||
2bff91f3 | 360 | /* Return the fallthru edge of a block whose other edge is an EH |
e53bb196 | 361 | edge. If EHP is not NULL, store the EH edge in it. */ |
2bff91f3 | 362 | static inline edge |
e53bb196 | 363 | non_eh_succ_edge (basic_block bb, edge *ehp = NULL) |
2bff91f3 AO |
364 | { |
365 | gcc_checking_assert (EDGE_COUNT (bb->succs) == 2); | |
366 | ||
367 | edge ret = find_fallthru_edge (bb->succs); | |
368 | ||
369 | int eh_idx = EDGE_SUCC (bb, 0) == ret; | |
370 | edge eh = EDGE_SUCC (bb, eh_idx); | |
371 | ||
372 | gcc_checking_assert (!(ret->flags & EDGE_EH) | |
373 | && (eh->flags & EDGE_EH)); | |
374 | ||
e53bb196 AO |
375 | if (ehp) |
376 | *ehp = eh; | |
377 | ||
2bff91f3 AO |
378 | return ret; |
379 | } | |
380 | ||
95bb87b2 AO |
381 | /* Harden boolean-yielding compares in FUN. */ |
382 | ||
383 | unsigned int | |
384 | pass_harden_compares::execute (function *fun) | |
385 | { | |
386 | basic_block bb; | |
387 | /* Go backwards over BBs and stmts, so that, even if we split the | |
388 | block multiple times to insert a cond_expr after each compare we | |
389 | find, we remain in the same block, visiting every preexisting | |
390 | stmt exactly once, and not visiting newly-added blocks or | |
391 | stmts. */ | |
392 | FOR_EACH_BB_REVERSE_FN (bb, fun) | |
393 | for (gimple_stmt_iterator gsi = gsi_last_bb (bb); | |
394 | !gsi_end_p (gsi); gsi_prev (&gsi)) | |
395 | { | |
396 | gassign *asgn = dyn_cast <gassign *> (gsi_stmt (gsi)); | |
397 | if (!asgn) | |
398 | continue; | |
399 | ||
400 | /* Turn: | |
401 | ||
402 | z = x op y; | |
403 | ||
404 | into: | |
405 | ||
406 | z = x op y; | |
407 | z' = x' cop y'; | |
408 | if (z == z') __builtin_trap (); | |
409 | ||
410 | where cop is a complementary boolean operation to op; and x' | |
411 | and y' hold the same value as x and y, but in a way that does | |
412 | not enable the compiler to optimize the redundant compare | |
413 | away. | |
414 | */ | |
415 | ||
416 | enum tree_code op = gimple_assign_rhs_code (asgn); | |
417 | ||
418 | enum tree_code cop; | |
419 | ||
420 | switch (op) | |
421 | { | |
422 | case EQ_EXPR: | |
423 | case NE_EXPR: | |
424 | case GT_EXPR: | |
425 | case GE_EXPR: | |
426 | case LT_EXPR: | |
427 | case LE_EXPR: | |
428 | case LTGT_EXPR: | |
429 | case UNEQ_EXPR: | |
430 | case UNGT_EXPR: | |
431 | case UNGE_EXPR: | |
432 | case UNLT_EXPR: | |
433 | case UNLE_EXPR: | |
434 | case ORDERED_EXPR: | |
435 | case UNORDERED_EXPR: | |
436 | cop = invert_tree_comparison (op, | |
437 | HONOR_NANS | |
438 | (gimple_assign_rhs1 (asgn))); | |
439 | ||
440 | if (cop == ERROR_MARK) | |
441 | /* ??? Can we do better? */ | |
442 | continue; | |
443 | ||
444 | break; | |
445 | ||
446 | /* ??? Maybe handle these too? */ | |
447 | case TRUTH_NOT_EXPR: | |
448 | /* ??? The code below assumes binary ops, it would have to | |
449 | be adjusted for TRUTH_NOT_EXPR, since it's unary. */ | |
450 | case TRUTH_ANDIF_EXPR: | |
451 | case TRUTH_ORIF_EXPR: | |
452 | case TRUTH_AND_EXPR: | |
453 | case TRUTH_OR_EXPR: | |
454 | case TRUTH_XOR_EXPR: | |
455 | default: | |
456 | continue; | |
457 | } | |
458 | ||
459 | /* These are the operands for the verification. */ | |
460 | tree lhs = gimple_assign_lhs (asgn); | |
461 | tree op1 = gimple_assign_rhs1 (asgn); | |
462 | tree op2 = gimple_assign_rhs2 (asgn); | |
463 | location_t loc = gimple_location (asgn); | |
464 | ||
465 | /* Vector booleans can't be used in conditional branches. ??? | |
466 | Can we do better? How to reduce compare and | |
467 | reversed-compare result vectors to a single boolean? */ | |
468 | if (VECTOR_TYPE_P (TREE_TYPE (op1))) | |
469 | continue; | |
470 | ||
2bff91f3 AO |
471 | /* useless_type_conversion_p enables conversions from 1-bit |
472 | integer types to boolean to be discarded. */ | |
473 | gcc_checking_assert (TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE | |
474 | || (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) | |
475 | && TYPE_PRECISION (TREE_TYPE (lhs)) == 1)); | |
95bb87b2 AO |
476 | |
477 | tree rhs = copy_ssa_name (lhs); | |
478 | ||
479 | gimple_stmt_iterator gsi_split = gsi; | |
480 | /* Don't separate the original assignment from debug stmts | |
481 | that might be associated with it, and arrange to split the | |
482 | block after debug stmts, so as to make sure the split block | |
483 | won't be debug stmts only. */ | |
484 | gsi_next_nondebug (&gsi_split); | |
485 | ||
2bff91f3 AO |
486 | bool throwing_compare_p = stmt_ends_bb_p (asgn); |
487 | if (throwing_compare_p) | |
488 | { | |
489 | basic_block nbb = split_edge (non_eh_succ_edge | |
490 | (gimple_bb (asgn))); | |
491 | gsi_split = gsi_start_bb (nbb); | |
492 | ||
493 | if (dump_file) | |
494 | fprintf (dump_file, | |
495 | "Splitting non-EH edge from block %i into %i" | |
496 | " after a throwing compare\n", | |
497 | gimple_bb (asgn)->index, nbb->index); | |
498 | } | |
499 | ||
95bb87b2 AO |
500 | bool same_p = (op1 == op2); |
501 | op1 = detach_value (loc, &gsi_split, op1); | |
502 | op2 = same_p ? op1 : detach_value (loc, &gsi_split, op2); | |
503 | ||
504 | gassign *asgnck = gimple_build_assign (rhs, cop, op1, op2); | |
505 | gimple_set_location (asgnck, loc); | |
506 | gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT); | |
507 | ||
508 | /* We wish to insert a cond_expr after the compare, so arrange | |
b8c4171e AO |
509 | for it to be at the end of a block if it isn't, and for it |
510 | to have a single successor in case there's more than | |
511 | one, as in PR104975. */ | |
512 | if (!gsi_end_p (gsi_split) | |
513 | || !single_succ_p (gsi_bb (gsi_split))) | |
95bb87b2 | 514 | { |
b8c4171e AO |
515 | if (!gsi_end_p (gsi_split)) |
516 | gsi_prev (&gsi_split); | |
517 | else | |
518 | gsi_split = gsi_last_bb (gsi_bb (gsi_split)); | |
2bff91f3 AO |
519 | basic_block obb = gsi_bb (gsi_split); |
520 | basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest; | |
95bb87b2 AO |
521 | gsi_next (&gsi_split); |
522 | gcc_checking_assert (gsi_end_p (gsi_split)); | |
523 | ||
524 | single_succ_edge (bb)->goto_locus = loc; | |
525 | ||
526 | if (dump_file) | |
2bff91f3 AO |
527 | fprintf (dump_file, |
528 | "Splitting block %i into %i" | |
529 | " before the conditional trap branch\n", | |
530 | obb->index, nbb->index); | |
531 | } | |
532 | ||
533 | /* If the check assignment must end a basic block, we can't | |
534 | insert the conditional branch in the same block, so split | |
535 | the block again, and prepare to insert the conditional | |
536 | branch in the new block. | |
537 | ||
538 | Also assign an EH region to the compare. Even though it's | |
539 | unlikely that the hardening compare will throw after the | |
540 | original compare didn't, the compiler won't even know that | |
541 | it's the same compare operands, so add the EH edge anyway. */ | |
542 | if (throwing_compare_p) | |
543 | { | |
544 | add_stmt_to_eh_lp (asgnck, lookup_stmt_eh_lp (asgn)); | |
545 | make_eh_edges (asgnck); | |
546 | ||
e53bb196 | 547 | edge ckeh; |
2bff91f3 | 548 | basic_block nbb = split_edge (non_eh_succ_edge |
e53bb196 | 549 | (gimple_bb (asgnck), &ckeh)); |
2bff91f3 AO |
550 | gsi_split = gsi_start_bb (nbb); |
551 | ||
552 | if (dump_file) | |
553 | fprintf (dump_file, | |
554 | "Splitting non-EH edge from block %i into %i after" | |
555 | " the newly-inserted reversed throwing compare\n", | |
556 | gimple_bb (asgnck)->index, nbb->index); | |
e53bb196 AO |
557 | |
558 | if (!gimple_seq_empty_p (phi_nodes (ckeh->dest))) | |
559 | { | |
560 | edge aseh; | |
561 | non_eh_succ_edge (gimple_bb (asgn), &aseh); | |
562 | ||
563 | gcc_checking_assert (aseh->dest == ckeh->dest); | |
564 | ||
565 | for (gphi_iterator psi = gsi_start_phis (ckeh->dest); | |
566 | !gsi_end_p (psi); gsi_next (&psi)) | |
567 | { | |
568 | gphi *phi = psi.phi (); | |
569 | add_phi_arg (phi, PHI_ARG_DEF_FROM_EDGE (phi, aseh), ckeh, | |
570 | gimple_phi_arg_location_from_edge (phi, aseh)); | |
571 | } | |
572 | ||
573 | if (dump_file) | |
574 | fprintf (dump_file, | |
575 | "Copying PHI args in EH block %i from %i to %i\n", | |
576 | aseh->dest->index, aseh->src->index, ckeh->src->index); | |
577 | } | |
95bb87b2 AO |
578 | } |
579 | ||
2bff91f3 | 580 | gcc_checking_assert (single_succ_p (gsi_bb (gsi_split))); |
95bb87b2 AO |
581 | |
582 | insert_check_and_trap (loc, &gsi_split, EDGE_TRUE_VALUE, | |
583 | EQ_EXPR, lhs, rhs); | |
584 | } | |
585 | ||
586 | return 0; | |
587 | } | |
588 | ||
589 | /* Instantiate a hardcmp pass. */ | |
590 | ||
591 | gimple_opt_pass * | |
592 | make_pass_harden_compares (gcc::context *ctxt) | |
593 | { | |
594 | return new pass_harden_compares (ctxt); | |
595 | } |