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1 : : /* Control flow redundancy hardening.
2 : : Copyright (C) 2022-2024 Free Software Foundation, Inc.
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 : : #define INCLUDE_ALGORITHM /* find */
23 : : #include "system.h"
24 : : #include "coretypes.h"
25 : : #include "backend.h"
26 : : #include "memmodel.h"
27 : : #include "tm_p.h"
28 : : #include "tree.h"
29 : : #include "fold-const.h"
30 : : #include "gimple.h"
31 : : #include "gimplify.h"
32 : : #include "tree-pass.h"
33 : : #include "ssa.h"
34 : : #include "gimple-iterator.h"
35 : : #include "gimple-pretty-print.h"
36 : : #include "tree-cfg.h"
37 : : #include "tree-cfgcleanup.h"
38 : : #include "tree-eh.h"
39 : : #include "except.h"
40 : : #include "sbitmap.h"
41 : : #include "basic-block.h"
42 : : #include "cfghooks.h"
43 : : #include "cfgloop.h"
44 : : #include "cgraph.h"
45 : : #include "alias.h"
46 : : #include "varasm.h"
47 : : #include "output.h"
48 : : #include "langhooks.h"
49 : : #include "diagnostic.h"
50 : : #include "intl.h"
51 : :
52 : : namespace {
53 : :
54 : : /* This pass introduces verification, at function exits, that booleans
55 : : set in each basic block during function execution reflect the
56 : : control flow graph: for each visited block, check that at least one
57 : : predecessor and at least one successor were also visited. This
58 : : sort of hardening may detect various kinds of attacks. */
59 : :
60 : : /* Define a pass to harden code through control flow redundancy. */
61 : :
62 : : const pass_data pass_data_harden_control_flow_redundancy = {
63 : : GIMPLE_PASS,
64 : : "hardcfr",
65 : : OPTGROUP_NONE,
66 : : TV_NONE,
67 : : PROP_cfg | PROP_ssa, // properties_required
68 : : 0, // properties_provided
69 : : 0, // properties_destroyed
70 : : TODO_cleanup_cfg, // properties_start
71 : : 0, // properties_finish
72 : : };
73 : :
74 : : class pass_harden_control_flow_redundancy : public gimple_opt_pass
75 : : {
76 : : public:
77 : 285189 : pass_harden_control_flow_redundancy (gcc::context *ctxt)
78 : 570378 : : gimple_opt_pass (pass_data_harden_control_flow_redundancy, ctxt)
79 : : {}
80 : 0 : opt_pass *clone () { return new pass_harden_control_flow_redundancy (m_ctxt); }
81 : 1419229 : virtual bool gate (function *fun) {
82 : : /* Return quickly if the pass is disabled, without checking any of
83 : : the conditions that might give rise to warnings that would only
84 : : be appropriate if hardening was requested. */
85 : 1419229 : if (!flag_harden_control_flow_redundancy)
86 : : return false;
87 : :
88 : : /* Functions that return more than once, like setjmp and vfork
89 : : (that also gets this flag set), will start recording a path
90 : : after the first return, and then may take another path when
91 : : they return again. The unterminated path may then be flagged
92 : : as an error. ??? We could save the visited array before the
93 : : call and restore it if it returns again. */
94 : 1740 : if (fun->calls_setjmp)
95 : : {
96 : 0 : warning_at (DECL_SOURCE_LOCATION (fun->decl), 0,
97 : : "%qD calls %<setjmp%> or similar,"
98 : : " %<-fharden-control-flow-redundancy%> is not supported",
99 : : fun->decl);
100 : 0 : return false;
101 : : }
102 : :
103 : : /* Some targets bypass the abnormal dispatcher block in nonlocal
104 : : gotos, and then we'd miss its visited bit. It might be doable
105 : : to make it work uniformly, but this feature is not used often
106 : : enough to make it worthwhile. */
107 : 1740 : if (fun->has_nonlocal_label)
108 : : {
109 : 0 : warning_at (DECL_SOURCE_LOCATION (fun->decl), 0,
110 : : "%qD receives nonlocal gotos,"
111 : : " %<-fharden-control-flow-redundancy%> is not supported",
112 : : fun->decl);
113 : 0 : return false;
114 : : }
115 : :
116 : 1740 : if (fun->cfg && param_hardcfr_max_blocks > 0
117 : 330 : && (n_basic_blocks_for_fn (fun) - NUM_FIXED_BLOCKS
118 : : > param_hardcfr_max_blocks))
119 : : {
120 : 82 : warning_at (DECL_SOURCE_LOCATION (fun->decl), 0,
121 : : "%qD has more than %u blocks, the requested"
122 : : " maximum for %<-fharden-control-flow-redundancy%>",
123 : : fun->decl, param_hardcfr_max_blocks);
124 : 82 : return false;
125 : : }
126 : :
127 : : return true;
128 : : }
129 : : virtual unsigned int execute (function *);
130 : : };
131 : :
132 : : }
133 : :
134 : : /* Return TRUE iff CFR checks should be inserted before returning
135 : : calls. */
136 : :
137 : : static bool
138 : 1161 : check_returning_calls_p ()
139 : : {
140 : 1161 : return
141 : 1161 : flag_harden_control_flow_redundancy_check_returning_calls > 0
142 : 1161 : || (flag_harden_control_flow_redundancy_check_returning_calls < 0
143 : : /* Gates pass_tail_calls. */
144 : 299 : && flag_optimize_sibling_calls
145 : : /* Gates pass_all_optimizations. */
146 : 248 : && optimize >= 1 && !optimize_debug);
147 : : }
148 : :
149 : : /* Scan BB from the end, updating *RETPTR if given as return stmts and
150 : : copies are found. Return a call or a stmt that cannot appear after
151 : : a tail call, or NULL if the top of the block is reached without
152 : : finding any. */
153 : :
154 : : static gimple *
155 : 2734 : hardcfr_scan_block (basic_block bb, tree **retptr)
156 : : {
157 : 2734 : gimple_stmt_iterator gsi;
158 : 8748 : for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
159 : : {
160 : 3391 : gimple *stmt = gsi_stmt (gsi);
161 : :
162 : : /* Ignore labels, returns, nops, clobbers and debug stmts. */
163 : 3391 : if (gimple_code (stmt) == GIMPLE_LABEL
164 : : || gimple_code (stmt) == GIMPLE_NOP
165 : : || gimple_code (stmt) == GIMPLE_PREDICT
166 : 3285 : || gimple_clobber_p (stmt)
167 : 3140 : || is_gimple_debug (stmt))
168 : 289 : continue;
169 : :
170 : 3102 : if (gimple_code (stmt) == GIMPLE_RETURN)
171 : : {
172 : 1308 : greturn *gret = as_a <greturn *> (stmt);
173 : 1308 : if (retptr)
174 : : {
175 : 1308 : gcc_checking_assert (!*retptr);
176 : 1308 : *retptr = gimple_return_retval_ptr (gret);
177 : : }
178 : 1308 : continue;
179 : 1308 : }
180 : :
181 : : /* Check for a call. */
182 : 1794 : if (is_gimple_call (stmt))
183 : 1259 : return stmt;
184 : :
185 : : /* Allow simple copies to the return value, updating the return
186 : : value to be found in earlier assignments. */
187 : 535 : if (retptr && *retptr && gimple_assign_single_p (stmt)
188 : 578 : && **retptr == gimple_assign_lhs (stmt))
189 : : {
190 : 43 : *retptr = gimple_assign_rhs1_ptr (stmt);
191 : 43 : continue;
192 : : }
193 : :
194 : : return stmt;
195 : : }
196 : :
197 : : /* Any other kind of stmt will prevent a tail call. */
198 : : return NULL;
199 : : }
200 : :
201 : : /* Return TRUE iff CALL is to be preceded by a CFR checkpoint, i.e.,
202 : : if it's a returning call (one whose result is ultimately returned
203 : : without intervening non-copy statements) and we're checking
204 : : returning calls, a __builtin_return call (noreturn with a path to
205 : : the exit block), a must-tail call, or a tail call. */
206 : :
207 : : static bool
208 : 911 : returning_call_p (gcall *call)
209 : : {
210 : 911 : if (!(gimple_call_noreturn_p (call)
211 : 494 : || gimple_call_must_tail_p (call)
212 : 494 : || gimple_call_tail_p (call)
213 : 494 : || check_returning_calls_p ()))
214 : : return false;
215 : :
216 : : /* Quickly check that there's a path to exit compatible with a
217 : : returning call. Detect infinite loops by limiting the path
218 : : length to the basic block count, and by looking for duplicate
219 : : blocks before allocating more memory for the path, for amortized
220 : : O(n). */
221 : 716 : auto_vec<basic_block, 10> path;
222 : 716 : for (basic_block bb = gimple_bb (call);
223 : 1435 : bb != EXIT_BLOCK_PTR_FOR_FN (cfun);
224 : 719 : bb = single_succ (bb))
225 : 884 : if (!single_succ_p (bb)
226 : 719 : || (single_succ_edge (bb)->flags & EDGE_EH) != 0
227 : 1438 : || n_basic_blocks_for_fn (cfun) - path.length () <= NUM_FIXED_BLOCKS
228 : 2322 : || (path.length () == path.allocated ()
229 : 0 : && std::find (path.begin (), path.end (), bb) != path.end ()))
230 : 165 : return false;
231 : : else
232 : 719 : path.safe_push (bb);
233 : :
234 : : /* Check the stmts in the blocks and trace the return value. */
235 : 551 : tree *retptr = NULL;
236 : 719 : for (;;)
237 : : {
238 : 719 : gcc_checking_assert (!path.is_empty ());
239 : 719 : basic_block bb = path.pop ();
240 : 719 : gimple *stop = hardcfr_scan_block (bb, &retptr);
241 : 719 : if (stop)
242 : : {
243 : 551 : if (stop != call)
244 : : return false;
245 : 531 : gcc_checking_assert (path.is_empty ());
246 : 531 : break;
247 : : }
248 : :
249 : 168 : gphi *retphi = NULL;
250 : 168 : if (retptr && *retptr && TREE_CODE (*retptr) == SSA_NAME
251 : 3 : && !SSA_NAME_IS_DEFAULT_DEF (*retptr)
252 : 3 : && SSA_NAME_DEF_STMT (*retptr)
253 : 3 : && is_a <gphi *> (SSA_NAME_DEF_STMT (*retptr))
254 : 168 : && gimple_bb (SSA_NAME_DEF_STMT (*retptr)) == bb)
255 : : {
256 : 0 : retphi = as_a <gphi *> (SSA_NAME_DEF_STMT (*retptr));
257 : 0 : gcc_checking_assert (gimple_phi_result (retphi) == *retptr);
258 : : }
259 : : else
260 : 168 : continue;
261 : :
262 : 0 : gcc_checking_assert (!path.is_empty ());
263 : 0 : edge e = single_succ_edge (path.last ());
264 : 0 : int i = EDGE_COUNT (bb->preds);
265 : 0 : while (i--)
266 : 0 : if (EDGE_PRED (bb, i) == e)
267 : : break;
268 : 0 : gcc_checking_assert (i >= 0);
269 : 0 : retptr = gimple_phi_arg_def_ptr (retphi, i);
270 : : }
271 : :
272 : 531 : return (gimple_call_noreturn_p (call)
273 : 259 : || gimple_call_must_tail_p (call)
274 : 259 : || gimple_call_tail_p (call)
275 : 790 : || (gimple_call_lhs (call) == (retptr ? *retptr : NULL)
276 : 259 : && check_returning_calls_p ()));
277 : 716 : }
278 : :
279 : : typedef auto_vec<edge, 10> chk_edges_t;
280 : :
281 : : /* Declare for mutual recursion. */
282 : : static bool hardcfr_sibcall_search_preds (basic_block bb,
283 : : chk_edges_t &chk_edges,
284 : : int &count_chkcall,
285 : : auto_sbitmap &chkcall_blocks,
286 : : int &count_postchk,
287 : : auto_sbitmap &postchk_blocks,
288 : : tree *retptr);
289 : :
290 : : /* Search backwards from the end of BB for a mandatory or potential
291 : : sibcall. Schedule the block to be handled sort-of like noreturn if
292 : : so. Recurse to preds, with updated RETPTR, if the block only
293 : : contains stmts that may follow such a call, scheduling checking at
294 : : edges and marking blocks as post-check as needed. Return true iff,
295 : : at the end of the block, a check will have already been
296 : : performed. */
297 : :
298 : : static bool
299 : 2672 : hardcfr_sibcall_search_block (basic_block bb,
300 : : chk_edges_t &chk_edges,
301 : : int &count_chkcall,
302 : : auto_sbitmap &chkcall_blocks,
303 : : int &count_postchk,
304 : : auto_sbitmap &postchk_blocks,
305 : : tree *retptr)
306 : : {
307 : : /* Conditionals and internal exceptions rule out tail calls. */
308 : 2672 : if (!single_succ_p (bb)
309 : 2672 : || (single_succ_edge (bb)->flags & EDGE_EH) != 0)
310 : : return false;
311 : :
312 : 2015 : gimple *stmt = hardcfr_scan_block (bb, &retptr);
313 : 2015 : if (!stmt)
314 : 815 : return hardcfr_sibcall_search_preds (bb, chk_edges,
315 : : count_chkcall, chkcall_blocks,
316 : : count_postchk, postchk_blocks,
317 : 815 : retptr);
318 : :
319 : 1200 : if (!is_a <gcall *> (stmt))
320 : : return false;
321 : :
322 : : /* Avoid disrupting mandatory or early-marked tail calls,
323 : : inserting the check before them. This works for
324 : : must-tail calls, but tail calling as an optimization is
325 : : detected too late for us.
326 : :
327 : : Also check for noreturn calls here. Noreturn calls won't
328 : : normally have edges to exit, so they won't be found here,
329 : : but __builtin_return does, and we must check before
330 : : it, so handle it like a tail call. */
331 : 708 : gcall *call = as_a <gcall *> (stmt);
332 : 1144 : if (!(gimple_call_noreturn_p (call)
333 : 436 : || gimple_call_must_tail_p (call)
334 : 436 : || gimple_call_tail_p (call)
335 : 436 : || (gimple_call_lhs (call) == (retptr ? *retptr : NULL)
336 : 408 : && check_returning_calls_p ())))
337 : : return false;
338 : :
339 : 486 : gcc_checking_assert (returning_call_p (call));
340 : :
341 : : /* We found a call that is to be preceded by checking. */
342 : 486 : if (bitmap_set_bit (chkcall_blocks, bb->index))
343 : 486 : ++count_chkcall;
344 : : else
345 : 0 : gcc_unreachable ();
346 : 486 : return true;
347 : : }
348 : :
349 : :
350 : : /* Search preds of BB for a mandatory or potential sibcall or
351 : : returning call, and arrange for the blocks containing them to have
352 : : a check inserted before the call, like noreturn calls. If any
353 : : preds are found to perform checking, schedule checks at the edges
354 : : of those that don't, and mark BB as postcheck.. */
355 : :
356 : : static bool
357 : 2357 : hardcfr_sibcall_search_preds (basic_block bb,
358 : : chk_edges_t &chk_edges,
359 : : int &count_chkcall,
360 : : auto_sbitmap &chkcall_blocks,
361 : : int &count_postchk,
362 : : auto_sbitmap &postchk_blocks,
363 : : tree *retptr)
364 : : {
365 : : /* For the exit block, we wish to force a check at every
366 : : predecessor, so pretend we've already found a pred that had
367 : : checking, so that we schedule checking at every one of its pred
368 : : edges. */
369 : 2357 : bool first = bb->index >= NUM_FIXED_BLOCKS;
370 : 2357 : bool postchecked = true;
371 : :
372 : 2357 : gphi *retphi = NULL;
373 : 815 : if (retptr && *retptr && TREE_CODE (*retptr) == SSA_NAME
374 : 289 : && !SSA_NAME_IS_DEFAULT_DEF (*retptr)
375 : 219 : && SSA_NAME_DEF_STMT (*retptr)
376 : 219 : && is_a <gphi *> (SSA_NAME_DEF_STMT (*retptr))
377 : 2521 : && gimple_bb (SSA_NAME_DEF_STMT (*retptr)) == bb)
378 : : {
379 : 164 : retphi = as_a <gphi *> (SSA_NAME_DEF_STMT (*retptr));
380 : 164 : gcc_checking_assert (gimple_phi_result (retphi) == *retptr);
381 : : }
382 : :
383 : 7336 : for (int i = EDGE_COUNT (bb->preds); i--; first = false)
384 : : {
385 : 2672 : edge e = EDGE_PRED (bb, i);
386 : :
387 : 2672 : bool checked
388 : 3164 : = hardcfr_sibcall_search_block (e->src, chk_edges,
389 : : count_chkcall, chkcall_blocks,
390 : : count_postchk, postchk_blocks,
391 : : !retphi ? retptr
392 : 492 : : gimple_phi_arg_def_ptr (retphi, i));
393 : :
394 : 2672 : if (first)
395 : : {
396 : 815 : postchecked = checked;
397 : 815 : continue;
398 : : }
399 : :
400 : : /* When we first find a checked block, force a check at every
401 : : other incoming edge we've already visited, and those we
402 : : visit afterwards that don't have their own check, so that
403 : : when we reach BB, the check has already been performed. */
404 : 1857 : if (!postchecked && checked)
405 : : {
406 : 3 : for (int j = EDGE_COUNT (bb->preds); --j > i; )
407 : 1 : chk_edges.safe_push (EDGE_PRED (bb, j));
408 : : postchecked = true;
409 : : }
410 : 1857 : if (postchecked && !checked)
411 : 928 : chk_edges.safe_push (EDGE_PRED (bb, i));
412 : : }
413 : :
414 : 2357 : if (postchecked && bb->index >= NUM_FIXED_BLOCKS)
415 : : {
416 : 78 : if (bitmap_set_bit (postchk_blocks, bb->index))
417 : 78 : count_postchk++;
418 : : else
419 : 0 : gcc_unreachable ();
420 : : }
421 : :
422 : 2357 : return postchecked;
423 : : }
424 : :
425 : :
426 : : class rt_bb_visited
427 : : {
428 : : /* Use a sufficiently wide unsigned type to hold basic block numbers. */
429 : : typedef size_t blknum;
430 : :
431 : : /* Record the original block count of the function. */
432 : : blknum nblocks;
433 : : /* Record the number of bits per VWORD (short for VISITED WORD), an
434 : : efficient mode to set and test bits for blocks we visited, and to
435 : : encode the CFG in case out-of-line verification is used. */
436 : : unsigned vword_bits;
437 : :
438 : : /* Hold the unsigned integral VWORD type. */
439 : : tree vword_type;
440 : : /* Hold a pointer-to-VWORD type. */
441 : : tree vword_ptr;
442 : :
443 : : /* Hold a growing sequence used to check, inline or out-of-line,
444 : : that VISITED encodes an expected execution path. */
445 : : gimple_seq ckseq;
446 : : /* If nonNULL, hold a growing representation of the CFG for
447 : : out-of-line testing. */
448 : : tree rtcfg;
449 : :
450 : : /* Hold the declaration of an array of VWORDs, used as an array of
451 : : NBLOCKS-2 bits. */
452 : : tree visited;
453 : :
454 : : /* If performing inline checking, hold a declarations of boolean
455 : : variables used for inline checking. CKBLK holds the result of
456 : : testing whether the VISITED bit corresponding to a predecessor or
457 : : successor is set, CKINV inverts that bit, CKPART gets cleared if
458 : : a block was not visited or if CKINV for any of its predecessors
459 : : or successors is set, and CKFAIL gets set if CKPART remains set
460 : : at the end of a block's predecessors or successors list. */
461 : : tree ckfail, ckpart, ckinv, ckblk;
462 : :
463 : : /* If we need to deal with abnormal edges, we insert SSA_NAMEs for
464 : : boolean true and false. */
465 : : tree vfalse, vtrue;
466 : :
467 : : /* Convert a block index N to a block vindex, the index used to
468 : : identify it in the VISITED array. Check that it's in range:
469 : : neither ENTRY nor EXIT, but maybe one-past-the-end, to compute
470 : : the visited array length. */
471 : 18820 : blknum num2idx (blknum n) {
472 : 18820 : gcc_checking_assert (n >= NUM_FIXED_BLOCKS && n <= nblocks);
473 : 18820 : return (n - NUM_FIXED_BLOCKS);
474 : : }
475 : : /* Return the block vindex for BB, that must not be ENTRY or
476 : : EXIT. */
477 : 15634 : blknum bb2idx (basic_block bb) {
478 : 15634 : gcc_checking_assert (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
479 : : && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
480 : 15634 : gcc_checking_assert (blknum (bb->index) < nblocks);
481 : 15634 : return num2idx (bb->index);
482 : : }
483 : :
484 : : /* Compute the type to be used for the VISITED array. */
485 : 1542 : tree vtype ()
486 : : {
487 : 1542 : blknum n = num2idx (nblocks);
488 : 3084 : return build_array_type_nelts (vword_type,
489 : 1542 : (n + vword_bits - 1) / vword_bits);
490 : : }
491 : :
492 : : /* Compute and return the index into VISITED for block BB. If BITP
493 : : is non-NULL, also compute and store the bit mask corresponding to
494 : : block BB in *BITP, so that (visited[index] & mask) tells whether
495 : : BB was visited. */
496 : 15634 : tree vwordidx (basic_block bb, tree *bitp = NULL)
497 : : {
498 : 15634 : blknum idx = bb2idx (bb);
499 : 15634 : if (bitp)
500 : : {
501 : 15634 : unsigned bit = idx % vword_bits;
502 : : /* We don't need to adjust shifts to follow native bit
503 : : endianness here, all of our uses of the CFG and visited
504 : : bitmaps, whether at compile or runtime, are shifted bits on
505 : : full words. This adjustment here would require a
506 : : corresponding adjustment at runtime, which would be nothing
507 : : but undesirable overhead for us. */
508 : 15634 : if (0 /* && BITS_BIG_ENDIAN */)
509 : : bit = vword_bits - bit - 1;
510 : 15634 : wide_int wbit = wi::set_bit_in_zero (bit, vword_bits);
511 : 15634 : *bitp = wide_int_to_tree (vword_type, wbit);
512 : 15634 : }
513 : 15634 : return build_int_cst (vword_ptr, idx / vword_bits);
514 : : }
515 : :
516 : : /* Return an expr to accesses the visited element that holds
517 : : information about BB. If BITP is non-NULL, set it to the mask to
518 : : tell which bit in that expr refers to BB. */
519 : 7368 : tree vword (basic_block bb, tree *bitp = NULL)
520 : : {
521 : 7368 : return build2 (MEM_REF, vword_type,
522 : : build1 (ADDR_EXPR, vword_ptr, visited),
523 : 7368 : int_const_binop (MULT_EXPR, vwordidx (bb, bitp),
524 : 7368 : fold_convert (vword_ptr,
525 : : TYPE_SIZE_UNIT
526 : 7368 : (vword_type))));
527 : : }
528 : :
529 : : /* Return an expr that evaluates to true iff BB was marked as
530 : : VISITED. Add any gimple stmts to SEQP. */
531 : 4636 : tree vindex (basic_block bb, gimple_seq *seqp)
532 : : {
533 : 4636 : if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun)
534 : 3916 : || bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
535 : 1878 : return boolean_true_node;
536 : :
537 : 2758 : tree bit, setme = vword (bb, &bit);
538 : 2758 : tree temp = create_tmp_var (vword_type, ".cfrtemp");
539 : :
540 : 2758 : gassign *vload = gimple_build_assign (temp, setme);
541 : 2758 : gimple_seq_add_stmt (seqp, vload);
542 : :
543 : 2758 : gassign *vmask = gimple_build_assign (temp, BIT_AND_EXPR, temp, bit);
544 : 2758 : gimple_seq_add_stmt (seqp, vmask);
545 : :
546 : 2758 : return build2 (NE_EXPR, boolean_type_node,
547 : 2758 : temp, build_int_cst (vword_type, 0));
548 : : }
549 : :
550 : : /* Set the bit corresponding to BB in VISITED. Add to SEQ any
551 : : required gimple stmts, and return SEQ, possibly modified. */
552 : 4610 : gimple_seq vset (basic_block bb, gimple_seq seq = NULL)
553 : : {
554 : 4610 : tree bit, setme = vword (bb, &bit);
555 : 4610 : tree temp = create_tmp_var (vword_type, ".cfrtemp");
556 : :
557 : 4610 : gassign *vload = gimple_build_assign (temp, setme);
558 : 4610 : gimple_seq_add_stmt (&seq, vload);
559 : :
560 : 4610 : gassign *vbitset = gimple_build_assign (temp, BIT_IOR_EXPR, temp, bit);
561 : 4610 : gimple_seq_add_stmt (&seq, vbitset);
562 : :
563 : 4610 : gassign *vstore = gimple_build_assign (unshare_expr (setme), temp);
564 : 4610 : gimple_seq_add_stmt (&seq, vstore);
565 : :
566 : : /* Prevent stores into visited from being deferred, forcing
567 : : subsequent bitsets to reload the word rather than reusing
568 : : values already in register. The purpose is threefold: make the
569 : : bitset get to memory in this block, so that control flow
570 : : attacks in functions called in this block don't easily bypass
571 : : the bitset; prevent the bitset word from being retained in a
572 : : register across blocks, which could, in an attack scenario,
573 : : make a later block set more than one bit; and prevent hoisting
574 : : or sinking loads or stores of bitset words out of loops or even
575 : : throughout functions, which could significantly weaken the
576 : : verification. This is equivalent to making the bitsetting
577 : : volatile within the function body, but without changing its
578 : : type; making the bitset volatile would make inline checking far
579 : : less optimizable for no reason. */
580 : 4610 : vec<tree, va_gc> *inputs = NULL;
581 : 4610 : vec<tree, va_gc> *outputs = NULL;
582 : 9220 : vec_safe_push (outputs,
583 : : build_tree_list
584 : 4610 : (build_tree_list
585 : : (NULL_TREE, build_string (2, "=m")),
586 : : visited));
587 : 9220 : vec_safe_push (inputs,
588 : : build_tree_list
589 : 4610 : (build_tree_list
590 : : (NULL_TREE, build_string (1, "m")),
591 : : visited));
592 : 4610 : gasm *stabilize = gimple_build_asm_vec ("", inputs, outputs,
593 : : NULL, NULL);
594 : 4610 : gimple_seq_add_stmt (&seq, stabilize);
595 : :
596 : 4610 : return seq;
597 : : }
598 : :
599 : : public:
600 : : /* Prepare to add control flow redundancy testing to CFUN. */
601 : 1542 : rt_bb_visited (int checkpoints)
602 : 1542 : : nblocks (n_basic_blocks_for_fn (cfun)),
603 : 1542 : vword_type (NULL), ckseq (NULL), rtcfg (NULL),
604 : 1542 : vfalse (NULL), vtrue (NULL)
605 : : {
606 : : /* If we've already added a declaration for the builtin checker,
607 : : extract vword_type and vword_bits from its declaration. */
608 : 1542 : if (tree checkfn = builtin_decl_explicit (BUILT_IN___HARDCFR_CHECK))
609 : : {
610 : 1026 : tree check_arg_list = TYPE_ARG_TYPES (TREE_TYPE (checkfn));
611 : 1026 : tree vword_const_ptr_type = TREE_VALUE (TREE_CHAIN (check_arg_list));
612 : 1026 : vword_type = TYPE_MAIN_VARIANT (TREE_TYPE (vword_const_ptr_type));
613 : 1026 : vword_bits = tree_to_shwi (TYPE_SIZE (vword_type));
614 : : }
615 : : /* Otherwise, select vword_bits, vword_type et al, and use it to
616 : : declare the builtin checker. */
617 : : else
618 : : {
619 : : /* This setting needs to be kept in sync with libgcc/hardcfr.c.
620 : : We aim for at least 28 bits, which enables us to refer to as
621 : : many as 28 << 28 blocks in a function's CFG. That's way over
622 : : 4G blocks. */
623 : 516 : machine_mode VWORDmode;
624 : 516 : if (BITS_PER_UNIT >= 28)
625 : : {
626 : : VWORDmode = QImode;
627 : : vword_bits = BITS_PER_UNIT;
628 : : }
629 : 516 : else if (BITS_PER_UNIT >= 14)
630 : : {
631 : : VWORDmode = HImode;
632 : : vword_bits = 2 * BITS_PER_UNIT;
633 : : }
634 : : else
635 : : {
636 : 516 : VWORDmode = SImode;
637 : 516 : vword_bits = 4 * BITS_PER_UNIT;
638 : : }
639 : :
640 : 516 : vword_type = lang_hooks.types.type_for_mode (VWORDmode, 1);
641 : 516 : gcc_checking_assert (vword_bits == tree_to_shwi (TYPE_SIZE
642 : : (vword_type)));
643 : :
644 : 516 : vword_type = build_variant_type_copy (vword_type);
645 : 516 : TYPE_ALIAS_SET (vword_type) = new_alias_set ();
646 : :
647 : 516 : tree vword_const = build_qualified_type (vword_type, TYPE_QUAL_CONST);
648 : 516 : tree vword_const_ptr = build_pointer_type (vword_const);
649 : 516 : tree type = build_function_type_list (void_type_node, sizetype,
650 : : vword_const_ptr, vword_const_ptr,
651 : : NULL_TREE);
652 : 516 : tree decl = add_builtin_function_ext_scope
653 : 516 : ("__builtin___hardcfr_check",
654 : : type, BUILT_IN___HARDCFR_CHECK, BUILT_IN_NORMAL,
655 : : "__hardcfr_check", NULL_TREE);
656 : 516 : TREE_NOTHROW (decl) = true;
657 : 516 : set_builtin_decl (BUILT_IN___HARDCFR_CHECK, decl, true);
658 : : }
659 : :
660 : : /* The checker uses a qualified pointer, so we can't reuse it,
661 : : so build a new one. */
662 : 1542 : vword_ptr = build_pointer_type (vword_type);
663 : :
664 : 1542 : tree visited_type = vtype ();
665 : 1542 : visited = create_tmp_var (visited_type, ".cfrvisited");
666 : :
667 : 1542 : if (nblocks - NUM_FIXED_BLOCKS > blknum (param_hardcfr_max_inline_blocks)
668 : 1444 : || checkpoints > 1)
669 : : {
670 : : /* Make sure vword_bits is wide enough for the representation
671 : : of nblocks in rtcfg. Compare with vword_bits << vword_bits,
672 : : but avoiding overflows, shifting nblocks right instead. If
673 : : vword_bits is wider than HOST_WIDE_INT, assume it fits, so
674 : : as to avoid undefined shifts. */
675 : 822 : gcc_assert (HOST_BITS_PER_WIDE_INT <= vword_bits
676 : : || (((unsigned HOST_WIDE_INT)(num2idx (nblocks))
677 : : >> vword_bits) < vword_bits));
678 : :
679 : : /* Build a terminator for the constructor list. */
680 : 822 : rtcfg = build_tree_list (NULL_TREE, NULL_TREE);
681 : 822 : return;
682 : : }
683 : :
684 : 720 : ckfail = create_tmp_var (boolean_type_node, ".cfrfail");
685 : 720 : ckpart = create_tmp_var (boolean_type_node, ".cfrpart");
686 : 720 : ckinv = create_tmp_var (boolean_type_node, ".cfrinv");
687 : 720 : ckblk = create_tmp_var (boolean_type_node, ".cfrblk");
688 : :
689 : 720 : gassign *ckfail_init = gimple_build_assign (ckfail, boolean_false_node);
690 : 720 : gimple_seq_add_stmt (&ckseq, ckfail_init);
691 : : }
692 : :
693 : : /* Insert SEQ before a resx or a call in INSBB. */
694 : 1426 : void insert_exit_check_in_block (gimple_seq seq, basic_block insbb)
695 : : {
696 : 1426 : gimple_stmt_iterator gsi = gsi_last_bb (insbb);
697 : :
698 : 1426 : while (!gsi_end_p (gsi))
699 : 1551 : if (is_a <gresx *> (gsi_stmt (gsi))
700 : 1551 : || is_a <gcall *> (gsi_stmt (gsi)))
701 : : break;
702 : : else
703 : 1676 : gsi_prev (&gsi);
704 : :
705 : 1426 : gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
706 : 1426 : }
707 : :
708 : : /* Insert SEQ on E. */
709 : 929 : void insert_exit_check_on_edge (gimple_seq seq, edge e)
710 : : {
711 : 929 : if (!(e->flags & EDGE_ABNORMAL))
712 : : {
713 : 928 : gsi_insert_seq_on_edge_immediate (e, seq);
714 : 928 : return;
715 : : }
716 : :
717 : : /* Initialize SSA boolean constants for use in abnormal PHIs. */
718 : 1 : if (!vfalse)
719 : : {
720 : 1 : vfalse = make_ssa_name (boolean_type_node);
721 : 1 : vtrue = make_ssa_name (boolean_type_node);
722 : :
723 : 1 : gimple_seq vft_seq = NULL;
724 : 1 : gassign *vfalse_init = gimple_build_assign (vfalse, boolean_false_node);
725 : 1 : gimple_seq_add_stmt (&vft_seq, vfalse_init);
726 : 1 : gassign *vtrue_init = gimple_build_assign (vtrue, boolean_true_node);
727 : 1 : gimple_seq_add_stmt (&vft_seq, vtrue_init);
728 : :
729 : 1 : gsi_insert_seq_on_edge_immediate (single_succ_edge
730 : 1 : (ENTRY_BLOCK_PTR_FOR_FN (cfun)),
731 : : vft_seq);
732 : : }
733 : :
734 : : /* We can't insert on abnormal edges, but we can arrange for SEQ
735 : : to execute conditionally at dest. Add a PHI boolean with TRUE
736 : : from E and FALSE from other preds, split the whole block, add a
737 : : test for the PHI to run a new block with SEQ or skip straight
738 : : to the original block. If there are multiple incoming abnormal
739 : : edges, we'll do this multiple times. ??? Unless there are
740 : : multiple abnormal edges with different postcheck status, we
741 : : could split the block and redirect other edges, rearranging the
742 : : PHI nodes. Optimizers already know how to do this, so we can
743 : : keep things simple here. */
744 : 1 : basic_block bb = e->dest;
745 : 1 : basic_block bb_postcheck = split_block_after_labels (bb)->dest;
746 : :
747 : 1 : basic_block bb_check = create_empty_bb (e->dest);
748 : 1 : bb_check->count = e->count ();
749 : 1 : if (dom_info_available_p (CDI_DOMINATORS))
750 : 1 : set_immediate_dominator (CDI_DOMINATORS, bb_check, bb);
751 : 1 : if (current_loops)
752 : 1 : add_bb_to_loop (bb_check, current_loops->tree_root);
753 : :
754 : 1 : gimple_stmt_iterator chkpt = gsi_after_labels (bb_check);
755 : 1 : gsi_insert_seq_before_without_update (&chkpt, seq, GSI_SAME_STMT);
756 : 1 : edge edge_postcheck = make_edge (bb_check, bb_postcheck, EDGE_FALLTHRU);
757 : 1 : edge_postcheck->probability = profile_probability::always ();
758 : :
759 : 1 : tree cond_var = make_ssa_name (boolean_type_node);
760 : 1 : gcond *cond = gimple_build_cond (NE_EXPR, cond_var, boolean_false_node,
761 : : NULL, NULL);
762 : 1 : gimple_stmt_iterator condpt = gsi_after_labels (bb);
763 : 1 : gsi_insert_before (&condpt, cond, GSI_SAME_STMT);
764 : 1 : edge edge_nocheck = single_succ_edge (bb);
765 : 1 : edge_nocheck->flags &= ~EDGE_FALLTHRU;
766 : 1 : edge_nocheck->flags |= EDGE_FALSE_VALUE;
767 : 1 : edge edge_check = make_edge (bb, bb_check, EDGE_TRUE_VALUE);
768 : 1 : edge_check->probability = e->count ().probability_in (bb->count);
769 : 1 : edge_nocheck->probability = edge_check->probability.invert ();
770 : :
771 : 1 : gphi *cond_phi = create_phi_node (cond_var, bb);
772 : 5 : for (int i = 0, ei = EDGE_COUNT (bb->preds); i < ei; i++)
773 : : {
774 : 3 : edge pred = EDGE_PRED (bb, i);
775 : 3 : bool check_edge = pred == e;
776 : 3 : tree val = check_edge ? vtrue : vfalse;
777 : 3 : add_phi_arg (cond_phi, val, pred, UNKNOWN_LOCATION);
778 : : }
779 : : }
780 : :
781 : : /* Add checking code to CHK_EDGES and CHKCALL_BLOCKS, and
782 : : initialization code on the entry edge. Before this point, the
783 : : CFG has been undisturbed, and all the needed data has been
784 : : collected and safely stowed. */
785 : 1542 : void check (chk_edges_t &chk_edges,
786 : : int count_chkcall, auto_sbitmap const &chkcall_blocks)
787 : : {
788 : : /* If we're using out-of-line checking, create and statically
789 : : initialize the CFG checking representation, generate the
790 : : checker call for the checking sequence, and insert it in all
791 : : exit edges, if there's more than one. If there's only one, we
792 : : use the same logic as the inline case to insert the check
793 : : sequence. */
794 : 1542 : if (rtcfg)
795 : : {
796 : : /* Unreverse the list, and drop the tail node turned into head. */
797 : 822 : rtcfg = TREE_CHAIN (nreverse (rtcfg));
798 : :
799 : : /* Turn the indices stored in TREE_PURPOSE into separate
800 : : nodes. It was useful to keep them together to enable
801 : : combination of masks and for clear separation of
802 : : terminators while constructing it, but now we have to turn
803 : : it into a sequence of words. */
804 : 20710 : for (tree node = rtcfg; node; node = TREE_CHAIN (node))
805 : : {
806 : 19888 : tree wordidx = TREE_PURPOSE (node);
807 : 19888 : if (!wordidx)
808 : 13308 : continue;
809 : :
810 : 6580 : TREE_PURPOSE (node) = NULL_TREE;
811 : 6580 : TREE_CHAIN (node) = tree_cons (NULL_TREE,
812 : : fold_convert (vword_type, wordidx),
813 : 6580 : TREE_CHAIN (node));
814 : : }
815 : :
816 : : /* Build the static initializer for the array with the CFG
817 : : representation for out-of-line checking. */
818 : 822 : tree init = build_constructor_from_list (NULL_TREE, rtcfg);
819 : 1644 : TREE_TYPE (init) = build_array_type_nelts (vword_type,
820 : 1644 : CONSTRUCTOR_NELTS (init));
821 : 822 : char buf[32];
822 : 822 : ASM_GENERATE_INTERNAL_LABEL (buf, "Lhardcfg",
823 : : current_function_funcdef_no);
824 : 822 : rtcfg = build_decl (UNKNOWN_LOCATION, VAR_DECL,
825 : : get_identifier (buf),
826 : 822 : TREE_TYPE (init));
827 : 822 : TREE_READONLY (rtcfg) = 1;
828 : 822 : TREE_STATIC (rtcfg) = 1;
829 : 822 : TREE_ADDRESSABLE (rtcfg) = 1;
830 : 822 : TREE_USED (rtcfg) = 1;
831 : 822 : DECL_ARTIFICIAL (rtcfg) = 1;
832 : 822 : DECL_IGNORED_P (rtcfg) = 1;
833 : 822 : DECL_INITIAL (rtcfg) = init;
834 : 822 : make_decl_rtl (rtcfg);
835 : 822 : varpool_node::finalize_decl (rtcfg);
836 : :
837 : : /* Add the checker call to ckseq. */
838 : 1644 : gcall *call_chk = gimple_build_call (builtin_decl_explicit
839 : : (BUILT_IN___HARDCFR_CHECK), 3,
840 : : build_int_cst (sizetype,
841 : 822 : num2idx (nblocks)),
842 : : build1 (ADDR_EXPR, vword_ptr,
843 : : visited),
844 : : build1 (ADDR_EXPR, vword_ptr,
845 : : rtcfg));
846 : 822 : gimple_seq_add_stmt (&ckseq, call_chk);
847 : :
848 : 822 : gimple *clobber = gimple_build_assign (visited,
849 : : build_clobber
850 : 822 : (TREE_TYPE (visited)));
851 : 822 : gimple_seq_add_stmt (&ckseq, clobber);
852 : :
853 : : /* If we have multiple exit edges, insert (copies of)
854 : : ckseq in all of them. */
855 : 2320 : for (int i = chk_edges.length (); i--; )
856 : : {
857 : 676 : gimple_seq seq = ckseq;
858 : : /* Copy the sequence, unless we're dealing with the
859 : : last edge (we're counting down to zero). */
860 : 676 : if (i || count_chkcall)
861 : 594 : seq = gimple_seq_copy (seq);
862 : :
863 : 676 : edge e = chk_edges[i];
864 : :
865 : 676 : if (dump_file)
866 : : {
867 : 675 : if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
868 : 634 : fprintf (dump_file,
869 : : "Inserting out-of-line check in"
870 : : " block %i's edge to exit.\n",
871 : 634 : e->src->index);
872 : : else
873 : 41 : fprintf (dump_file,
874 : : "Inserting out-of-line check in"
875 : : " block %i's edge to postcheck block %i.\n",
876 : 41 : e->src->index, e->dest->index);
877 : : }
878 : :
879 : 676 : insert_exit_check_on_edge (seq, e);
880 : :
881 : 676 : gcc_checking_assert (!bitmap_bit_p (chkcall_blocks, e->src->index));
882 : : }
883 : :
884 : 822 : sbitmap_iterator it;
885 : 822 : unsigned i;
886 : 2603 : EXECUTE_IF_SET_IN_BITMAP (chkcall_blocks, 0, i, it)
887 : : {
888 : 959 : basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i);
889 : :
890 : 959 : gimple_seq seq = ckseq;
891 : 959 : gcc_checking_assert (count_chkcall > 0);
892 : 959 : if (--count_chkcall)
893 : 219 : seq = gimple_seq_copy (seq);
894 : :
895 : 959 : if (dump_file)
896 : 958 : fprintf (dump_file,
897 : : "Inserting out-of-line check before stmt in block %i.\n",
898 : : bb->index);
899 : :
900 : 959 : insert_exit_check_in_block (seq, bb);
901 : : }
902 : :
903 : 822 : gcc_checking_assert (count_chkcall == 0);
904 : : }
905 : : else
906 : : {
907 : : /* Inline checking requires a single exit edge. */
908 : 720 : gimple *last = gimple_build_assign (visited,
909 : : build_clobber
910 : 720 : (TREE_TYPE (visited)));
911 : 720 : gimple_seq_add_stmt (&ckseq, last);
912 : :
913 : 720 : if (!count_chkcall)
914 : : {
915 : 253 : edge e = single_pred_edge (EXIT_BLOCK_PTR_FOR_FN (cfun));
916 : :
917 : 253 : if (dump_file)
918 : : {
919 : 253 : if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
920 : 253 : fprintf (dump_file,
921 : : "Inserting out-of-line check in"
922 : : " block %i's edge to postcheck block %i.\n",
923 : 253 : e->src->index, e->dest->index);
924 : : else
925 : 0 : fprintf (dump_file,
926 : : "Inserting inline check in"
927 : : " block %i's edge to exit.\n",
928 : 0 : e->src->index);
929 : : }
930 : :
931 : 253 : insert_exit_check_on_edge (ckseq, e);
932 : : }
933 : : else
934 : : {
935 : 467 : gcc_checking_assert (count_chkcall == 1);
936 : :
937 : 467 : sbitmap_iterator it;
938 : 467 : unsigned i;
939 : 1401 : EXECUTE_IF_SET_IN_BITMAP (chkcall_blocks, 0, i, it)
940 : : {
941 : 467 : basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i);
942 : :
943 : 467 : gimple_seq seq = ckseq;
944 : 467 : gcc_checking_assert (count_chkcall > 0);
945 : 467 : if (--count_chkcall)
946 : : seq = gimple_seq_copy (seq);
947 : :
948 : 467 : if (dump_file)
949 : 467 : fprintf (dump_file,
950 : : "Inserting inline check before stmt in block %i.\n",
951 : : bb->index);
952 : :
953 : 467 : insert_exit_check_in_block (seq, bb);
954 : : }
955 : :
956 : 467 : gcc_checking_assert (count_chkcall == 0);
957 : : }
958 : :
959 : : /* The inserted ckseq computes CKFAIL at LAST. Now we have to
960 : : conditionally trap on it. */
961 : 720 : basic_block insbb = gimple_bb (last);
962 : :
963 : : /* Create a block with the unconditional trap. */
964 : 720 : basic_block trp = create_empty_bb (insbb);
965 : 720 : gimple_stmt_iterator gsit = gsi_after_labels (trp);
966 : :
967 : 720 : gcall *trap = gimple_build_call (builtin_decl_explicit
968 : : (BUILT_IN_TRAP), 0);
969 : 720 : gsi_insert_before (&gsit, trap, GSI_SAME_STMT);
970 : :
971 : 720 : if (BB_PARTITION (insbb))
972 : 0 : BB_SET_PARTITION (trp, BB_COLD_PARTITION);
973 : :
974 : 720 : if (current_loops)
975 : 720 : add_bb_to_loop (trp, current_loops->tree_root);
976 : :
977 : : /* Insert a conditional branch to the trap block. If the
978 : : conditional wouldn't be the last stmt, split the block. */
979 : 720 : gimple_stmt_iterator gsi = gsi_for_stmt (last);
980 : 720 : if (!gsi_one_before_end_p (gsi))
981 : 720 : split_block (gsi_bb (gsi), gsi_stmt (gsi));
982 : :
983 : 720 : gcond *cond = gimple_build_cond (NE_EXPR, ckfail,
984 : 720 : fold_convert (TREE_TYPE (ckfail),
985 : : boolean_false_node),
986 : : NULL, NULL);
987 : 720 : gsi_insert_after (&gsi, cond, GSI_SAME_STMT);
988 : :
989 : : /* Adjust the edges. */
990 : 720 : single_succ_edge (gsi_bb (gsi))->flags &= ~EDGE_FALLTHRU;
991 : 720 : single_succ_edge (gsi_bb (gsi))->flags |= EDGE_FALSE_VALUE;
992 : 720 : single_succ_edge (gsi_bb (gsi))->probability
993 : 720 : = profile_probability::always ();
994 : 720 : edge e = make_edge (gsi_bb (gsi), trp, EDGE_TRUE_VALUE);
995 : 720 : e->probability = profile_probability::never ();
996 : 720 : gcc_checking_assert (e->dest == trp);
997 : 720 : gcc_checking_assert (!e->dest->count.initialized_p ());
998 : 720 : e->dest->count = e->count ();
999 : :
1000 : : /* Set the trap's dominator after splitting. */
1001 : 720 : if (dom_info_available_p (CDI_DOMINATORS))
1002 : 720 : set_immediate_dominator (CDI_DOMINATORS, trp, gimple_bb (last));
1003 : : }
1004 : :
1005 : : /* Insert initializers for visited at the entry. Do this after
1006 : : other insertions, to avoid messing with block numbers. */
1007 : 1542 : gimple_seq iseq = NULL;
1008 : :
1009 : 1542 : gcall *vinit = gimple_build_call (builtin_decl_explicit
1010 : : (BUILT_IN_MEMSET), 3,
1011 : : build1 (ADDR_EXPR,
1012 : : build_pointer_type
1013 : 1542 : (TREE_TYPE (visited)),
1014 : : visited),
1015 : : integer_zero_node,
1016 : 1542 : TYPE_SIZE_UNIT (TREE_TYPE (visited)));
1017 : 1542 : gimple_seq_add_stmt (&iseq, vinit);
1018 : :
1019 : 1542 : gsi_insert_seq_on_edge_immediate (single_succ_edge
1020 : 1542 : (ENTRY_BLOCK_PTR_FOR_FN (cfun)),
1021 : : iseq);
1022 : 1542 : }
1023 : :
1024 : : /* Push onto RTCFG a (mask, index) pair to test for IBB when BB is
1025 : : visited. XSELF is to be the ENTRY or EXIT block (depending on
1026 : : whether we're looking at preds or succs), to be remapped to BB
1027 : : because we can't represent them, and there's no point in testing
1028 : : them anyway. Return true if no further blocks need to be visited
1029 : : in the list, because we've already encountered a
1030 : : self-reference. */
1031 : : bool
1032 : 8266 : push_rtcfg_pair (basic_block ibb, basic_block bb,
1033 : : basic_block xself)
1034 : : {
1035 : : /* We don't have a bit to test for the entry and exit
1036 : : blocks, but it is always visited, so we test for the
1037 : : block itself, which gets us the right result and
1038 : : enables the self-test optimization below. */
1039 : 8266 : if (ibb == xself)
1040 : 2457 : ibb = bb;
1041 : :
1042 : 8266 : tree mask, idx = vwordidx (ibb, &mask);
1043 : : /* Combine masks with the same idx, but not if we're going
1044 : : to optimize for self-test. */
1045 : 5809 : if (ibb != bb && TREE_PURPOSE (rtcfg)
1046 : 9952 : && tree_int_cst_equal (idx, TREE_PURPOSE (rtcfg)))
1047 : 1686 : TREE_VALUE (rtcfg) = int_const_binop (BIT_IOR_EXPR, mask,
1048 : 1686 : TREE_VALUE (rtcfg));
1049 : : else
1050 : 6580 : rtcfg = tree_cons (idx, mask, rtcfg);
1051 : :
1052 : : /* For self-tests (i.e., tests that the block itself was
1053 : : also visited), testing anything else is pointless,
1054 : : because it's a tautology, so just drop other edges. */
1055 : 8266 : if (ibb == bb)
1056 : : {
1057 : 2457 : while (TREE_PURPOSE (TREE_CHAIN (rtcfg)))
1058 : 0 : TREE_CHAIN (rtcfg) = TREE_CHAIN (TREE_CHAIN (rtcfg));
1059 : : return true;
1060 : : }
1061 : :
1062 : : return false;
1063 : : }
1064 : :
1065 : : /* Add to CKSEQ stmts to clear CKPART if OBB is visited. */
1066 : : void
1067 : 3316 : build_block_check (basic_block obb)
1068 : : {
1069 : 3316 : tree vobb = fold_convert (TREE_TYPE (ckblk),
1070 : : vindex (obb, &ckseq));
1071 : 3316 : gassign *blkrunp = gimple_build_assign (ckblk, vobb);
1072 : 3316 : gimple_seq_add_stmt (&ckseq, blkrunp);
1073 : :
1074 : 3316 : gassign *blknotrunp = gimple_build_assign (ckinv,
1075 : : EQ_EXPR,
1076 : : ckblk,
1077 : 3316 : fold_convert
1078 : : (TREE_TYPE (ckblk),
1079 : : boolean_false_node));
1080 : 3316 : gimple_seq_add_stmt (&ckseq, blknotrunp);
1081 : :
1082 : 3316 : gassign *andblk = gimple_build_assign (ckpart,
1083 : : BIT_AND_EXPR,
1084 : : ckpart, ckinv);
1085 : 3316 : gimple_seq_add_stmt (&ckseq, andblk);
1086 : 3316 : }
1087 : :
1088 : : /* Add to BB code to set its bit in VISITED, and add to RTCFG or
1089 : : CKSEQ the data or code needed to check BB's predecessors and
1090 : : successors. If CHECKPOINT, assume the block is a checkpoint,
1091 : : whether or not it has an edge to EXIT. If POSTCHECK, assume the
1092 : : block post-dominates checkpoints and therefore no bitmap setting
1093 : : or checks are to be performed in or for it. Do NOT change the
1094 : : CFG. */
1095 : 4688 : void visit (basic_block bb, bool checkpoint, bool postcheck)
1096 : : {
1097 : : /* Set the bit in VISITED when entering the block. */
1098 : 4688 : gimple_stmt_iterator gsi = gsi_after_labels (bb);
1099 : 4688 : if (!postcheck)
1100 : 4610 : gsi_insert_seq_before (&gsi, vset (bb), GSI_SAME_STMT);
1101 : :
1102 : 4688 : if (rtcfg)
1103 : : {
1104 : 3364 : if (!postcheck)
1105 : : {
1106 : : /* Build a list of (index, mask) terminated by (NULL, 0).
1107 : : Consolidate masks with the same index when they're
1108 : : adjacent. First, predecessors. Count backwards, because
1109 : : we're going to reverse the list. The order shouldn't
1110 : : matter, but let's not make it surprising. */
1111 : 9520 : for (int i = EDGE_COUNT (bb->preds); i--; )
1112 : 3762 : if (push_rtcfg_pair (EDGE_PRED (bb, i)->src, bb,
1113 : 3762 : ENTRY_BLOCK_PTR_FOR_FN (cfun)))
1114 : : break;
1115 : : }
1116 : 3364 : rtcfg = tree_cons (NULL_TREE, build_int_cst (vword_type, 0), rtcfg);
1117 : :
1118 : 3364 : if (!postcheck)
1119 : : {
1120 : : /* Then, successors. */
1121 : 3290 : if (!checkpoint
1122 : 4925 : || !push_rtcfg_pair (EXIT_BLOCK_PTR_FOR_FN (cfun),
1123 : 1635 : bb, EXIT_BLOCK_PTR_FOR_FN (cfun)))
1124 : 6179 : for (int i = EDGE_COUNT (bb->succs); i--; )
1125 : 2869 : if (push_rtcfg_pair (EDGE_SUCC (bb, i)->dest, bb,
1126 : 2869 : EXIT_BLOCK_PTR_FOR_FN (cfun)))
1127 : : break;
1128 : : }
1129 : 3364 : rtcfg = tree_cons (NULL_TREE, build_int_cst (vword_type, 0), rtcfg);
1130 : : }
1131 : 1324 : else if (!postcheck)
1132 : : {
1133 : : /* Schedule test to fail if the block was reached but somehow none
1134 : : of its predecessors were. */
1135 : 1320 : tree bit = fold_convert (TREE_TYPE (ckpart), vindex (bb, &ckseq));
1136 : 1320 : gassign *blkrunp = gimple_build_assign (ckpart, bit);
1137 : 1320 : gimple_seq_add_stmt (&ckseq, blkrunp);
1138 : :
1139 : 4077 : for (int i = 0, e = EDGE_COUNT (bb->preds); i < e; i++)
1140 : 1437 : build_block_check (EDGE_PRED (bb, i)->src);
1141 : 1320 : gimple *orfailp = gimple_build_assign (ckfail, BIT_IOR_EXPR,
1142 : : ckfail, ckpart);
1143 : 1320 : gimple_seq_add_stmt (&ckseq, orfailp);
1144 : :
1145 : : /* Likewise for successors. */
1146 : 1320 : gassign *blkruns = gimple_build_assign (ckpart, unshare_expr (bit));
1147 : 1320 : gimple_seq_add_stmt (&ckseq, blkruns);
1148 : :
1149 : 1320 : if (checkpoint)
1150 : 720 : build_block_check (EXIT_BLOCK_PTR_FOR_FN (cfun));
1151 : 3661 : for (int i = 0, e = EDGE_COUNT (bb->succs); i < e; i++)
1152 : 1159 : build_block_check (EDGE_SUCC (bb, i)->dest);
1153 : :
1154 : 1320 : gimple *orfails = gimple_build_assign (ckfail, BIT_IOR_EXPR,
1155 : : ckfail, ckpart);
1156 : 1320 : gimple_seq_add_stmt (&ckseq, orfails);
1157 : : }
1158 : 4688 : }
1159 : : };
1160 : :
1161 : : /* Avoid checking before noreturn calls that are known (expected,
1162 : : really) to finish by throwing an exception, rather than by ending
1163 : : the program or looping forever. Such functions have to be
1164 : : annotated, with an attribute (expected_throw) or flag (ECF_XTHROW),
1165 : : so that exception-raising functions, such as C++'s __cxa_throw,
1166 : : __cxa_rethrow, and Ada's gnat_rcheck_*, gnat_reraise*,
1167 : : ada.exception.raise_exception*, and the language-independent
1168 : : unwinders could be detected here and handled differently from other
1169 : : noreturn functions. */
1170 : : static bool
1171 : 335 : always_throwing_noreturn_call_p (gimple *stmt)
1172 : : {
1173 : 335 : if (!is_a <gcall *> (stmt))
1174 : 0 : return is_a <gresx *> (stmt);
1175 : :
1176 : 335 : gcall *call = as_a <gcall *> (stmt);
1177 : 335 : return (gimple_call_noreturn_p (call)
1178 : 670 : && gimple_call_expected_throw_p (call));
1179 : : }
1180 : :
1181 : : /* Control flow redundancy hardening: record the execution path, and
1182 : : verify at exit that an expect path was taken. */
1183 : :
1184 : : unsigned int
1185 : 1658 : pass_harden_control_flow_redundancy::execute (function *fun)
1186 : : {
1187 : 3316 : bool const check_at_escaping_exceptions
1188 : 1658 : = (flag_exceptions
1189 : 1658 : && flag_harden_control_flow_redundancy_check_exceptions);
1190 : 1658 : bool const check_before_noreturn_calls
1191 : 1658 : = flag_harden_control_flow_redundancy_check_noreturn > HCFRNR_NEVER;
1192 : 3316 : bool const check_before_nothrow_noreturn_calls
1193 : : = (check_before_noreturn_calls
1194 : 1658 : && flag_harden_control_flow_redundancy_check_noreturn >= HCFRNR_NOTHROW);
1195 : 3316 : bool const check_before_throwing_noreturn_calls
1196 : : = (flag_exceptions
1197 : 939 : && check_before_noreturn_calls
1198 : 2359 : && flag_harden_control_flow_redundancy_check_noreturn > HCFRNR_NOTHROW);
1199 : 3316 : bool const check_before_always_throwing_noreturn_calls
1200 : : = (flag_exceptions
1201 : 939 : && check_before_noreturn_calls
1202 : 2359 : && flag_harden_control_flow_redundancy_check_noreturn >= HCFRNR_ALWAYS);
1203 : 1658 : basic_block bb;
1204 : 1658 : basic_block bb_eh_cleanup = NULL;
1205 : :
1206 : 1658 : if (flag_harden_control_flow_redundancy_skip_leaf)
1207 : : {
1208 : 66 : bool found_calls_p = false;
1209 : :
1210 : 424 : FOR_EACH_BB_FN (bb, fun)
1211 : : {
1212 : 376 : for (gimple_stmt_iterator gsi = gsi_last_bb (bb);
1213 : 1726 : !gsi_end_p (gsi); gsi_prev (&gsi))
1214 : 693 : if (is_a <gcall *> (gsi_stmt (gsi)))
1215 : : {
1216 : : found_calls_p = true;
1217 : : break;
1218 : : }
1219 : 376 : if (found_calls_p)
1220 : : break;
1221 : : }
1222 : :
1223 : 66 : if (!found_calls_p)
1224 : : {
1225 : 48 : if (dump_file)
1226 : 48 : fprintf (dump_file,
1227 : : "Disabling CFR for leaf function, as requested\n");
1228 : :
1229 : 48 : return 0;
1230 : : }
1231 : : }
1232 : :
1233 : 1610 : if (check_at_escaping_exceptions)
1234 : : {
1235 : 796 : int lp_eh_cleanup = -1;
1236 : :
1237 : : /* Record the preexisting blocks, to avoid visiting newly-created
1238 : : blocks. */
1239 : 796 : auto_sbitmap to_visit (last_basic_block_for_fn (fun));
1240 : 796 : bitmap_clear (to_visit);
1241 : :
1242 : 3056 : FOR_EACH_BB_FN (bb, fun)
1243 : 2260 : bitmap_set_bit (to_visit, bb->index);
1244 : :
1245 : : /* Scan the blocks for stmts with escaping exceptions, that
1246 : : wouldn't be denoted in the CFG, and associate them with an
1247 : : empty cleanup handler around the whole function. Walk
1248 : : backwards, so that even when we split the block, */
1249 : 796 : sbitmap_iterator it;
1250 : 796 : unsigned i;
1251 : 3852 : EXECUTE_IF_SET_IN_BITMAP (to_visit, 0, i, it)
1252 : : {
1253 : 2260 : bb = BASIC_BLOCK_FOR_FN (fun, i);
1254 : :
1255 : 2260 : for (gimple_stmt_iterator gsi = gsi_last_bb (bb);
1256 : 10662 : !gsi_end_p (gsi); gsi_prev (&gsi))
1257 : : {
1258 : 4201 : gimple *stmt = gsi_stmt (gsi);
1259 : 4201 : if (!stmt_could_throw_p (fun, stmt))
1260 : 3205 : continue;
1261 : :
1262 : : /* If it must not throw, or if it already has a handler,
1263 : : we need not worry about it. */
1264 : 996 : if (lookup_stmt_eh_lp (stmt) != 0)
1265 : 387 : continue;
1266 : :
1267 : : /* Don't split blocks at, nor add EH edges to, tail
1268 : : calls, we will add verification before the call
1269 : : anyway. */
1270 : 609 : if (is_a <gcall *> (stmt)
1271 : 609 : && (gimple_call_must_tail_p (as_a <gcall *> (stmt))
1272 : 425 : || gimple_call_tail_p (as_a <gcall *> (stmt))
1273 : 425 : || returning_call_p (as_a <gcall *> (stmt))))
1274 : 45 : continue;
1275 : :
1276 : 564 : if (!gsi_one_before_end_p (gsi))
1277 : 107 : split_block (bb, stmt);
1278 : : /* A resx or noreturn call needs not be associated with
1279 : : the cleanup handler if we're going to add checking
1280 : : before it. We only test cases that didn't require
1281 : : block splitting because noreturn calls would always
1282 : : be at the end of blocks, and we test for zero
1283 : : successors because if there is an edge, it's not
1284 : : noreturn, as any EH edges would have already been
1285 : : caught by the lookup_stmt_eh_lp test above. */
1286 : 522 : else if (check_before_noreturn_calls
1287 : 359 : && EDGE_COUNT (bb->succs) == 0
1288 : 708 : && (is_a <gresx *> (stmt)
1289 : 110 : ? check_before_always_throwing_noreturn_calls
1290 : 110 : : (!is_a <gcall *> (stmt)
1291 : 110 : || !gimple_call_noreturn_p (stmt))
1292 : 110 : ? (gcc_unreachable (), false)
1293 : 110 : : (!flag_exceptions
1294 : 110 : || gimple_call_nothrow_p (as_a <gcall *> (stmt)))
1295 : 220 : ? check_before_nothrow_noreturn_calls
1296 : 110 : : always_throwing_noreturn_call_p (stmt)
1297 : : ? check_before_always_throwing_noreturn_calls
1298 : : : check_before_throwing_noreturn_calls))
1299 : : {
1300 : 65 : if (dump_file)
1301 : : {
1302 : 65 : fprintf (dump_file,
1303 : : "Bypassing cleanup for noreturn stmt"
1304 : : " in block %i:\n",
1305 : : bb->index);
1306 : 65 : print_gimple_stmt (dump_file, stmt, 0);
1307 : : }
1308 : 65 : continue;
1309 : : }
1310 : :
1311 : 499 : if (!bb_eh_cleanup)
1312 : : {
1313 : 421 : bb_eh_cleanup = create_empty_bb (bb);
1314 : 421 : if (dom_info_available_p (CDI_DOMINATORS))
1315 : 421 : set_immediate_dominator (CDI_DOMINATORS, bb_eh_cleanup, bb);
1316 : 421 : if (current_loops)
1317 : 421 : add_bb_to_loop (bb_eh_cleanup, current_loops->tree_root);
1318 : :
1319 : : /* Make the new block an EH cleanup for the call. */
1320 : 421 : eh_region new_r = gen_eh_region_cleanup (NULL);
1321 : 421 : eh_landing_pad lp = gen_eh_landing_pad (new_r);
1322 : 421 : tree label = gimple_block_label (bb_eh_cleanup);
1323 : 421 : lp->post_landing_pad = label;
1324 : 421 : EH_LANDING_PAD_NR (label) = lp_eh_cleanup = lp->index;
1325 : :
1326 : : /* Just propagate the exception.
1327 : : We will later insert the verifier call. */
1328 : 421 : gimple_stmt_iterator ehgsi;
1329 : 421 : ehgsi = gsi_after_labels (bb_eh_cleanup);
1330 : 421 : gresx *resx = gimple_build_resx (new_r->index);
1331 : 421 : gsi_insert_before (&ehgsi, resx, GSI_SAME_STMT);
1332 : :
1333 : 421 : if (dump_file)
1334 : 420 : fprintf (dump_file,
1335 : : "Created cleanup block %i:\n",
1336 : : bb_eh_cleanup->index);
1337 : : }
1338 : 78 : else if (dom_info_available_p (CDI_DOMINATORS))
1339 : : {
1340 : 78 : basic_block immdom;
1341 : 78 : immdom = get_immediate_dominator (CDI_DOMINATORS,
1342 : : bb_eh_cleanup);
1343 : 78 : if (!dominated_by_p (CDI_DOMINATORS, bb, immdom))
1344 : : {
1345 : 78 : immdom = nearest_common_dominator (CDI_DOMINATORS,
1346 : : immdom, bb);
1347 : 78 : set_immediate_dominator (CDI_DOMINATORS,
1348 : : bb_eh_cleanup, immdom);
1349 : : }
1350 : : }
1351 : :
1352 : 499 : if (dump_file)
1353 : : {
1354 : 498 : fprintf (dump_file,
1355 : : "Associated cleanup block with stmt in block %i:\n",
1356 : : bb->index);
1357 : 498 : print_gimple_stmt (dump_file, stmt, 0);
1358 : : }
1359 : :
1360 : 499 : add_stmt_to_eh_lp (stmt, lp_eh_cleanup);
1361 : : /* Finally, wire the EH cleanup block into the CFG. */
1362 : 499 : edge neeh = make_eh_edge (stmt);
1363 : 499 : neeh->probability = profile_probability::never ();
1364 : 499 : gcc_checking_assert (neeh->dest == bb_eh_cleanup);
1365 : 499 : if (neeh->dest->count.initialized_p ())
1366 : 78 : neeh->dest->count += neeh->count ();
1367 : : else
1368 : 421 : neeh->dest->count = neeh->count ();
1369 : : }
1370 : : }
1371 : :
1372 : 796 : if (bb_eh_cleanup)
1373 : : {
1374 : : /* A cfg_cleanup after bb_eh_cleanup makes for a more compact
1375 : : rtcfg, and it avoids bb numbering differences when we split
1376 : : blocks because of trailing debug insns only. */
1377 : 421 : cleanup_tree_cfg ();
1378 : 796 : gcc_checking_assert (EDGE_COUNT (bb_eh_cleanup->succs) == 0);
1379 : : }
1380 : 796 : }
1381 : :
1382 : : /* These record blocks with calls that are to be preceded by
1383 : : checkpoints, such as noreturn calls (if so chosen), must-tail
1384 : : calls, potential early-marked tail calls, and returning calls (if
1385 : : so chosen). */
1386 : 1610 : int count_chkcall = 0;
1387 : 1610 : auto_sbitmap chkcall_blocks (last_basic_block_for_fn (fun));
1388 : 1610 : bitmap_clear (chkcall_blocks);
1389 : :
1390 : : /* We wish to add verification at blocks without successors, such as
1391 : : noreturn calls (raising or not) and the reraise at the cleanup
1392 : : block, but not other reraises: they will go through the cleanup
1393 : : block. */
1394 : 1610 : if (check_before_noreturn_calls)
1395 : 4898 : FOR_EACH_BB_FN (bb, fun)
1396 : : {
1397 : 3679 : gimple_stmt_iterator gsi = gsi_last_bb (bb);
1398 : 3679 : if (gsi_end_p (gsi))
1399 : 3679 : continue;
1400 : 3670 : gimple *stmt = gsi_stmt (gsi);
1401 : :
1402 : 3670 : if (EDGE_COUNT (bb->succs) == 0)
1403 : : {
1404 : : /* A stmt at the end of a block without any successors is
1405 : : either a resx or a noreturn call without a local
1406 : : handler. Check that it's one of the desired
1407 : : checkpoints. */
1408 : 1382 : if (flag_exceptions && is_a <gresx *> (stmt)
1409 : 1268 : ? (check_before_always_throwing_noreturn_calls
1410 : 356 : || bb == bb_eh_cleanup)
1411 : 456 : : (!is_a <gcall *> (stmt)
1412 : 456 : || !gimple_call_noreturn_p (stmt))
1413 : 456 : ? (stmt_can_make_abnormal_goto (stmt)
1414 : : /* ??? Check before indirect nonlocal goto, or
1415 : : calls thereof? */
1416 : 0 : ? false
1417 : : /* Catch cases in which successors would be
1418 : : expected. */
1419 : 0 : : (gcc_unreachable (), false))
1420 : 456 : : (!flag_exceptions
1421 : 214 : || gimple_call_nothrow_p (as_a <gcall *> (stmt)))
1422 : 670 : ? check_before_nothrow_noreturn_calls
1423 : 32 : : always_throwing_noreturn_call_p (stmt)
1424 : : ? check_before_always_throwing_noreturn_calls
1425 : : : check_before_throwing_noreturn_calls)
1426 : : {
1427 : 812 : if (dump_file)
1428 : : {
1429 : 811 : fprintf (dump_file,
1430 : : "Scheduling check before stmt"
1431 : : " in succ-less block %i:\n",
1432 : : bb->index);
1433 : 811 : print_gimple_stmt (dump_file, stmt, 0);
1434 : : }
1435 : :
1436 : 812 : if (bitmap_set_bit (chkcall_blocks, bb->index))
1437 : 812 : count_chkcall++;
1438 : : else
1439 : 0 : gcc_unreachable ();
1440 : : }
1441 : 812 : continue;
1442 : : }
1443 : :
1444 : : /* If there are no exceptions, it would seem like any noreturn
1445 : : call must have zero successor edges, but __builtin_return
1446 : : gets successor edges. We don't want to handle it here, it
1447 : : will be dealt with in sibcall_search_preds. Otherwise,
1448 : : check for blocks without non-EH successors, but skip those
1449 : : with resx stmts and edges (i.e., those other than that in
1450 : : bb_eh_cleanup), since those will go through bb_eh_cleanup,
1451 : : that will have been counted as noreturn above because it
1452 : : has no successors. */
1453 : 2858 : gcc_checking_assert (bb != bb_eh_cleanup
1454 : : || !check_at_escaping_exceptions);
1455 : 1706 : if (flag_exceptions && is_a <gresx *> (stmt)
1456 : 2858 : ? check_before_always_throwing_noreturn_calls
1457 : 2734 : : (!is_a <gcall *> (stmt)
1458 : 815 : || !gimple_call_noreturn_p (stmt))
1459 : 2734 : ? false
1460 : 373 : : (!flag_exceptions
1461 : 221 : || gimple_call_nothrow_p (as_a <gcall *> (stmt)))
1462 : 193 : ? false /* rather than check_before_nothrow_noreturn_calls */
1463 : 193 : : always_throwing_noreturn_call_p (stmt)
1464 : 193 : ? check_before_always_throwing_noreturn_calls
1465 : : : check_before_throwing_noreturn_calls)
1466 : : {
1467 : 60 : gcc_checking_assert (single_succ_p (bb)
1468 : : && (single_succ_edge (bb)->flags & EDGE_EH));
1469 : :
1470 : 30 : if (dump_file)
1471 : : {
1472 : 30 : fprintf (dump_file,
1473 : : "Scheduling check before stmt"
1474 : : " in EH-succ block %i:\n",
1475 : : bb->index);
1476 : 30 : print_gimple_stmt (dump_file, stmt, 0);
1477 : : }
1478 : :
1479 : 30 : if (bitmap_set_bit (chkcall_blocks, bb->index))
1480 : 30 : count_chkcall++;
1481 : : else
1482 : 0 : gcc_unreachable ();
1483 : : }
1484 : : }
1485 : 391 : else if (bb_eh_cleanup)
1486 : : {
1487 : 98 : if (bitmap_set_bit (chkcall_blocks, bb_eh_cleanup->index))
1488 : 98 : count_chkcall++;
1489 : : else
1490 : 0 : gcc_unreachable ();
1491 : : }
1492 : :
1493 : 1317 : gcc_checking_assert (!bb_eh_cleanup
1494 : : || bitmap_bit_p (chkcall_blocks, bb_eh_cleanup->index));
1495 : :
1496 : : /* If we don't have edges to exit nor noreturn calls (including the
1497 : : cleanup reraise), then we may skip instrumentation: that would
1498 : : amount to a function that ends with an infinite loop. */
1499 : 1610 : if (!count_chkcall
1500 : 1610 : && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (fun)->preds) == 0)
1501 : : {
1502 : 68 : if (dump_file)
1503 : 68 : fprintf (dump_file,
1504 : : "Disabling CFR, no exit paths to check\n");
1505 : :
1506 : 68 : return 0;
1507 : : }
1508 : :
1509 : : /* Search for must-tail calls, early-marked potential tail calls,
1510 : : and, if requested, returning calls. As we introduce early
1511 : : checks, */
1512 : 1542 : int count_postchk = 0;
1513 : 1542 : auto_sbitmap postchk_blocks (last_basic_block_for_fn (fun));
1514 : 1542 : bitmap_clear (postchk_blocks);
1515 : 1542 : chk_edges_t chk_edges;
1516 : 1542 : hardcfr_sibcall_search_preds (EXIT_BLOCK_PTR_FOR_FN (fun), chk_edges,
1517 : : count_chkcall, chkcall_blocks,
1518 : : count_postchk, postchk_blocks,
1519 : : NULL);
1520 : :
1521 : 3084 : rt_bb_visited vstd (chk_edges.length () + count_chkcall);
1522 : :
1523 : 1542 : auto_sbitmap combined_blocks (last_basic_block_for_fn (fun));
1524 : 1542 : bitmap_copy (combined_blocks, chkcall_blocks);
1525 : 1542 : int i;
1526 : 1542 : edge *e;
1527 : 4013 : FOR_EACH_VEC_ELT (chk_edges, i, e)
1528 : 929 : if (!bitmap_set_bit (combined_blocks, (*e)->src->index))
1529 : : /* There may be multiple chk_edges with the same src block;
1530 : : guard againt overlaps with chkcall_blocks only. */
1531 : 0 : gcc_assert (!bitmap_bit_p (chkcall_blocks, (*e)->src->index));
1532 : :
1533 : : /* Visit blocks in index order, because building rtcfg depends on
1534 : : that. Blocks must be compact, which the cleanup_cfg requirement
1535 : : ensures. This would also enable FOR_EACH_BB_FN to be used to
1536 : : iterate in index order, but bb_eh_cleanup block splits and
1537 : : insertions changes that. */
1538 : 1542 : gcc_checking_assert (n_basic_blocks_for_fn (fun)
1539 : : == last_basic_block_for_fn (fun));
1540 : 6230 : for (int i = NUM_FIXED_BLOCKS; i < n_basic_blocks_for_fn (fun); i++)
1541 : : {
1542 : 4688 : bb = BASIC_BLOCK_FOR_FN (fun, i);
1543 : 4688 : gcc_checking_assert (bb->index == i);
1544 : 4688 : vstd.visit (bb, bitmap_bit_p (combined_blocks, i),
1545 : 4688 : bitmap_bit_p (postchk_blocks, i));
1546 : : }
1547 : :
1548 : 1542 : vstd.check (chk_edges, count_chkcall, chkcall_blocks);
1549 : :
1550 : 1542 : return
1551 : : TODO_update_ssa
1552 : : | TODO_cleanup_cfg
1553 : 1542 : | TODO_verify_il;
1554 : 1610 : }
1555 : :
1556 : : /* Instantiate a hardcfr pass. */
1557 : :
1558 : : gimple_opt_pass *
1559 : 285189 : make_pass_harden_control_flow_redundancy (gcc::context *ctxt)
1560 : : {
1561 : 285189 : return new pass_harden_control_flow_redundancy (ctxt);
1562 : : }
|
