c, c++: attribute format on a ctor with a vbase [PR101833, PR47634]
[official-gcc.git] / gcc / gimple-ssa-warn-access.cc
blob39aa8186de6f08d493b3c295e881d1e0a89dccb1
1 /* Pass to detect and issue warnings for invalid accesses, including
2 invalid or mismatched allocation/deallocation calls.
4 Copyright (C) 2020-2022 Free Software Foundation, Inc.
5 Contributed by Martin Sebor <msebor@redhat.com>.
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it under
10 the terms of the GNU General Public License as published by the Free
11 Software Foundation; either version 3, or (at your option) any later
12 version.
14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
23 #define INCLUDE_STRING
24 #include "config.h"
25 #include "system.h"
26 #include "coretypes.h"
27 #include "backend.h"
28 #include "tree.h"
29 #include "gimple.h"
30 #include "tree-pass.h"
31 #include "builtins.h"
32 #include "diagnostic.h"
33 #include "ssa.h"
34 #include "gimple-pretty-print.h"
35 #include "gimple-ssa-warn-access.h"
36 #include "gimple-ssa-warn-restrict.h"
37 #include "diagnostic-core.h"
38 #include "fold-const.h"
39 #include "gimple-fold.h"
40 #include "gimple-iterator.h"
41 #include "langhooks.h"
42 #include "memmodel.h"
43 #include "target.h"
44 #include "tree-dfa.h"
45 #include "tree-ssa.h"
46 #include "tree-cfg.h"
47 #include "tree-object-size.h"
48 #include "tree-ssa-strlen.h"
49 #include "calls.h"
50 #include "cfganal.h"
51 #include "intl.h"
52 #include "gimple-range.h"
53 #include "stringpool.h"
54 #include "attribs.h"
55 #include "demangle.h"
56 #include "attr-fnspec.h"
57 #include "pointer-query.h"
59 /* Return true if tree node X has an associated location. */
61 static inline location_t
62 has_location (const_tree x)
64 if (DECL_P (x))
65 return DECL_SOURCE_LOCATION (x) != UNKNOWN_LOCATION;
67 if (EXPR_P (x))
68 return EXPR_HAS_LOCATION (x);
70 return false;
73 /* Return the associated location of STMT. */
75 static inline location_t
76 get_location (const gimple *stmt)
78 return gimple_location (stmt);
81 /* Return the associated location of tree node X. */
83 static inline location_t
84 get_location (tree x)
86 if (DECL_P (x))
87 return DECL_SOURCE_LOCATION (x);
89 if (EXPR_P (x))
90 return EXPR_LOCATION (x);
92 return UNKNOWN_LOCATION;
95 /* Overload of the nascent tree function for GIMPLE STMT. */
97 static inline tree
98 get_callee_fndecl (const gimple *stmt)
100 return gimple_call_fndecl (stmt);
103 static inline unsigned
104 call_nargs (const gimple *stmt)
106 return gimple_call_num_args (stmt);
109 static inline unsigned
110 call_nargs (const_tree expr)
112 return call_expr_nargs (expr);
116 static inline tree
117 call_arg (const gimple *stmt, unsigned argno)
119 return gimple_call_arg (stmt, argno);
122 static inline tree
123 call_arg (tree expr, unsigned argno)
125 return CALL_EXPR_ARG (expr, argno);
128 /* For a call EXPR at LOC to a function FNAME that expects a string
129 in the argument ARG, issue a diagnostic due to it being a called
130 with an argument that is a character array with no terminating
131 NUL. SIZE is the EXACT size of the array, and BNDRNG the number
132 of characters in which the NUL is expected. Either EXPR or FNAME
133 may be null but noth both. SIZE may be null when BNDRNG is null. */
135 template <class GimpleOrTree>
136 static void
137 warn_string_no_nul (location_t loc, GimpleOrTree expr, const char *fname,
138 tree arg, tree decl, tree size, bool exact,
139 const wide_int bndrng[2] /* = NULL */)
141 const opt_code opt = OPT_Wstringop_overread;
142 if ((expr && warning_suppressed_p (expr, opt))
143 || warning_suppressed_p (arg, opt))
144 return;
146 loc = expansion_point_location_if_in_system_header (loc);
147 bool warned;
149 /* Format the bound range as a string to keep the number of messages
150 from exploding. */
151 char bndstr[80];
152 *bndstr = 0;
153 if (bndrng)
155 if (bndrng[0] == bndrng[1])
156 sprintf (bndstr, "%llu", (unsigned long long) bndrng[0].to_uhwi ());
157 else
158 sprintf (bndstr, "[%llu, %llu]",
159 (unsigned long long) bndrng[0].to_uhwi (),
160 (unsigned long long) bndrng[1].to_uhwi ());
163 const tree maxobjsize = max_object_size ();
164 const wide_int maxsiz = wi::to_wide (maxobjsize);
165 if (expr)
167 tree func = get_callee_fndecl (expr);
168 if (bndrng)
170 if (wi::ltu_p (maxsiz, bndrng[0]))
171 warned = warning_at (loc, opt,
172 "%qD specified bound %s exceeds "
173 "maximum object size %E",
174 func, bndstr, maxobjsize);
175 else
177 bool maybe = wi::to_wide (size) == bndrng[0];
178 warned = warning_at (loc, opt,
179 exact
180 ? G_("%qD specified bound %s exceeds "
181 "the size %E of unterminated array")
182 : (maybe
183 ? G_("%qD specified bound %s may "
184 "exceed the size of at most %E "
185 "of unterminated array")
186 : G_("%qD specified bound %s exceeds "
187 "the size of at most %E "
188 "of unterminated array")),
189 func, bndstr, size);
192 else
193 warned = warning_at (loc, opt,
194 "%qD argument missing terminating nul",
195 func);
197 else
199 if (bndrng)
201 if (wi::ltu_p (maxsiz, bndrng[0]))
202 warned = warning_at (loc, opt,
203 "%qs specified bound %s exceeds "
204 "maximum object size %E",
205 fname, bndstr, maxobjsize);
206 else
208 bool maybe = wi::to_wide (size) == bndrng[0];
209 warned = warning_at (loc, opt,
210 exact
211 ? G_("%qs specified bound %s exceeds "
212 "the size %E of unterminated array")
213 : (maybe
214 ? G_("%qs specified bound %s may "
215 "exceed the size of at most %E "
216 "of unterminated array")
217 : G_("%qs specified bound %s exceeds "
218 "the size of at most %E "
219 "of unterminated array")),
220 fname, bndstr, size);
223 else
224 warned = warning_at (loc, opt,
225 "%qs argument missing terminating nul",
226 fname);
229 if (warned)
231 inform (get_location (decl),
232 "referenced argument declared here");
233 suppress_warning (arg, opt);
234 if (expr)
235 suppress_warning (expr, opt);
239 void
240 warn_string_no_nul (location_t loc, gimple *stmt, const char *fname,
241 tree arg, tree decl, tree size /* = NULL_TREE */,
242 bool exact /* = false */,
243 const wide_int bndrng[2] /* = NULL */)
245 return warn_string_no_nul<gimple *> (loc, stmt, fname,
246 arg, decl, size, exact, bndrng);
249 void
250 warn_string_no_nul (location_t loc, tree expr, const char *fname,
251 tree arg, tree decl, tree size /* = NULL_TREE */,
252 bool exact /* = false */,
253 const wide_int bndrng[2] /* = NULL */)
255 return warn_string_no_nul<tree> (loc, expr, fname,
256 arg, decl, size, exact, bndrng);
259 /* If EXP refers to an unterminated constant character array return
260 the declaration of the object of which the array is a member or
261 element and if SIZE is not null, set *SIZE to the size of
262 the unterminated array and set *EXACT if the size is exact or
263 clear it otherwise. Otherwise return null. */
265 tree
266 unterminated_array (tree exp, tree *size /* = NULL */, bool *exact /* = NULL */)
268 /* C_STRLEN will return NULL and set DECL in the info
269 structure if EXP references a unterminated array. */
270 c_strlen_data lendata = { };
271 tree len = c_strlen (exp, 1, &lendata);
272 if (len || !lendata.minlen || !lendata.decl)
273 return NULL_TREE;
275 if (!size)
276 return lendata.decl;
278 len = lendata.minlen;
279 if (lendata.off)
281 /* Constant offsets are already accounted for in LENDATA.MINLEN,
282 but not in a SSA_NAME + CST expression. */
283 if (TREE_CODE (lendata.off) == INTEGER_CST)
284 *exact = true;
285 else if (TREE_CODE (lendata.off) == PLUS_EXPR
286 && TREE_CODE (TREE_OPERAND (lendata.off, 1)) == INTEGER_CST)
288 /* Subtract the offset from the size of the array. */
289 *exact = false;
290 tree temp = TREE_OPERAND (lendata.off, 1);
291 temp = fold_convert (ssizetype, temp);
292 len = fold_build2 (MINUS_EXPR, ssizetype, len, temp);
294 else
295 *exact = false;
297 else
298 *exact = true;
300 *size = len;
301 return lendata.decl;
304 /* For a call EXPR (which may be null) that expects a string argument
305 SRC as an argument, returns false if SRC is a character array with
306 no terminating NUL. When nonnull, BOUND is the number of characters
307 in which to expect the terminating NUL. When EXPR is nonnull also
308 issues a warning. */
310 template <class GimpleOrTree>
311 static bool
312 check_nul_terminated_array (GimpleOrTree expr, tree src, tree bound)
314 /* The constant size of the array SRC points to. The actual size
315 may be less of EXACT is true, but not more. */
316 tree size;
317 /* True if SRC involves a non-constant offset into the array. */
318 bool exact;
319 /* The unterminated constant array SRC points to. */
320 tree nonstr = unterminated_array (src, &size, &exact);
321 if (!nonstr)
322 return true;
324 /* NONSTR refers to the non-nul terminated constant array and SIZE
325 is the constant size of the array in bytes. EXACT is true when
326 SIZE is exact. */
328 wide_int bndrng[2];
329 if (bound)
331 value_range r;
333 get_global_range_query ()->range_of_expr (r, bound);
335 if (r.kind () != VR_RANGE)
336 return true;
338 bndrng[0] = r.lower_bound ();
339 bndrng[1] = r.upper_bound ();
341 if (exact)
343 if (wi::leu_p (bndrng[0], wi::to_wide (size)))
344 return true;
346 else if (wi::lt_p (bndrng[0], wi::to_wide (size), UNSIGNED))
347 return true;
350 if (expr)
351 warn_string_no_nul (get_location (expr), expr, NULL, src, nonstr,
352 size, exact, bound ? bndrng : NULL);
354 return false;
357 bool
358 check_nul_terminated_array (gimple *stmt, tree src, tree bound /* = NULL_TREE */)
360 return check_nul_terminated_array<gimple *>(stmt, src, bound);
363 bool
364 check_nul_terminated_array (tree expr, tree src, tree bound /* = NULL_TREE */)
366 return check_nul_terminated_array<tree>(expr, src, bound);
369 /* Warn about passing a non-string array/pointer to a built-in function
370 that expects a nul-terminated string argument. Returns true if
371 a warning has been issued.*/
373 template <class GimpleOrTree>
374 static bool
375 maybe_warn_nonstring_arg (tree fndecl, GimpleOrTree exp)
377 if (!fndecl || !fndecl_built_in_p (fndecl, BUILT_IN_NORMAL))
378 return false;
380 if (!warn_stringop_overread
381 || warning_suppressed_p (exp, OPT_Wstringop_overread))
382 return false;
384 /* Avoid clearly invalid calls (more checking done below). */
385 unsigned nargs = call_nargs (exp);
386 if (!nargs)
387 return false;
389 /* The bound argument to a bounded string function like strncpy. */
390 tree bound = NULL_TREE;
392 /* The longest known or possible string argument to one of the comparison
393 functions. If the length is less than the bound it is used instead.
394 Since the length is only used for warning and not for code generation
395 disable strict mode in the calls to get_range_strlen below. */
396 tree maxlen = NULL_TREE;
398 /* It's safe to call "bounded" string functions with a non-string
399 argument since the functions provide an explicit bound for this
400 purpose. The exception is strncat where the bound may refer to
401 either the destination or the source. */
402 int fncode = DECL_FUNCTION_CODE (fndecl);
403 switch (fncode)
405 case BUILT_IN_STRCMP:
406 case BUILT_IN_STRNCMP:
407 case BUILT_IN_STRNCASECMP:
409 /* For these, if one argument refers to one or more of a set
410 of string constants or arrays of known size, determine
411 the range of their known or possible lengths and use it
412 conservatively as the bound for the unbounded function,
413 and to adjust the range of the bound of the bounded ones. */
414 for (unsigned argno = 0;
415 argno < MIN (nargs, 2)
416 && !(maxlen && TREE_CODE (maxlen) == INTEGER_CST); argno++)
418 tree arg = call_arg (exp, argno);
419 if (!get_attr_nonstring_decl (arg))
421 c_strlen_data lendata = { };
422 /* Set MAXBOUND to an arbitrary non-null non-integer
423 node as a request to have it set to the length of
424 the longest string in a PHI. */
425 lendata.maxbound = arg;
426 get_range_strlen (arg, &lendata, /* eltsize = */ 1);
427 maxlen = lendata.maxbound;
431 /* Fall through. */
433 case BUILT_IN_STRNCAT:
434 case BUILT_IN_STPNCPY:
435 case BUILT_IN_STRNCPY:
436 if (nargs > 2)
437 bound = call_arg (exp, 2);
438 break;
440 case BUILT_IN_STRNDUP:
441 if (nargs < 2)
442 return false;
443 bound = call_arg (exp, 1);
444 break;
446 case BUILT_IN_STRNLEN:
448 tree arg = call_arg (exp, 0);
449 if (!get_attr_nonstring_decl (arg))
451 c_strlen_data lendata = { };
452 /* Set MAXBOUND to an arbitrary non-null non-integer
453 node as a request to have it set to the length of
454 the longest string in a PHI. */
455 lendata.maxbound = arg;
456 get_range_strlen (arg, &lendata, /* eltsize = */ 1);
457 maxlen = lendata.maxbound;
459 if (nargs > 1)
460 bound = call_arg (exp, 1);
461 break;
464 default:
465 break;
468 /* Determine the range of the bound argument (if specified). */
469 tree bndrng[2] = { NULL_TREE, NULL_TREE };
470 if (bound)
472 STRIP_NOPS (bound);
473 get_size_range (bound, bndrng);
476 location_t loc = get_location (exp);
478 if (bndrng[0])
480 /* Diagnose excessive bound prior to the adjustment below and
481 regardless of attribute nonstring. */
482 tree maxobjsize = max_object_size ();
483 if (tree_int_cst_lt (maxobjsize, bndrng[0]))
485 bool warned = false;
486 if (tree_int_cst_equal (bndrng[0], bndrng[1]))
487 warned = warning_at (loc, OPT_Wstringop_overread,
488 "%qD specified bound %E "
489 "exceeds maximum object size %E",
490 fndecl, bndrng[0], maxobjsize);
491 else
492 warned = warning_at (loc, OPT_Wstringop_overread,
493 "%qD specified bound [%E, %E] "
494 "exceeds maximum object size %E",
495 fndecl, bndrng[0], bndrng[1],
496 maxobjsize);
497 if (warned)
498 suppress_warning (exp, OPT_Wstringop_overread);
500 return warned;
504 if (maxlen && !integer_all_onesp (maxlen))
506 /* Add one for the nul. */
507 maxlen = const_binop (PLUS_EXPR, TREE_TYPE (maxlen), maxlen,
508 size_one_node);
510 if (!bndrng[0])
512 /* Conservatively use the upper bound of the lengths for
513 both the lower and the upper bound of the operation. */
514 bndrng[0] = maxlen;
515 bndrng[1] = maxlen;
516 bound = void_type_node;
518 else if (maxlen)
520 /* Replace the bound on the operation with the upper bound
521 of the length of the string if the latter is smaller. */
522 if (tree_int_cst_lt (maxlen, bndrng[0]))
523 bndrng[0] = maxlen;
524 else if (tree_int_cst_lt (maxlen, bndrng[1]))
525 bndrng[1] = maxlen;
529 bool any_arg_warned = false;
530 /* Iterate over the built-in function's formal arguments and check
531 each const char* against the actual argument. If the actual
532 argument is declared attribute non-string issue a warning unless
533 the argument's maximum length is bounded. */
534 function_args_iterator it;
535 function_args_iter_init (&it, TREE_TYPE (fndecl));
537 for (unsigned argno = 0; ; ++argno, function_args_iter_next (&it))
539 /* Avoid iterating past the declared argument in a call
540 to function declared without a prototype. */
541 if (argno >= nargs)
542 break;
544 tree argtype = function_args_iter_cond (&it);
545 if (!argtype)
546 break;
548 if (TREE_CODE (argtype) != POINTER_TYPE)
549 continue;
551 argtype = TREE_TYPE (argtype);
553 if (TREE_CODE (argtype) != INTEGER_TYPE
554 || !TYPE_READONLY (argtype))
555 continue;
557 argtype = TYPE_MAIN_VARIANT (argtype);
558 if (argtype != char_type_node)
559 continue;
561 tree callarg = call_arg (exp, argno);
562 if (TREE_CODE (callarg) == ADDR_EXPR)
563 callarg = TREE_OPERAND (callarg, 0);
565 /* See if the destination is declared with attribute "nonstring". */
566 tree decl = get_attr_nonstring_decl (callarg);
567 if (!decl)
568 continue;
570 /* The maximum number of array elements accessed. */
571 offset_int wibnd = 0;
573 if (argno && fncode == BUILT_IN_STRNCAT)
575 /* See if the bound in strncat is derived from the length
576 of the strlen of the destination (as it's expected to be).
577 If so, reset BOUND and FNCODE to trigger a warning. */
578 tree dstarg = call_arg (exp, 0);
579 if (is_strlen_related_p (dstarg, bound))
581 /* The bound applies to the destination, not to the source,
582 so reset these to trigger a warning without mentioning
583 the bound. */
584 bound = NULL;
585 fncode = 0;
587 else if (bndrng[1])
588 /* Use the upper bound of the range for strncat. */
589 wibnd = wi::to_offset (bndrng[1]);
591 else if (bndrng[0])
592 /* Use the lower bound of the range for functions other than
593 strncat. */
594 wibnd = wi::to_offset (bndrng[0]);
596 /* Determine the size of the argument array if it is one. */
597 offset_int asize = wibnd;
598 bool known_size = false;
599 tree type = TREE_TYPE (decl);
601 /* Determine the array size. For arrays of unknown bound and
602 pointers reset BOUND to trigger the appropriate warning. */
603 if (TREE_CODE (type) == ARRAY_TYPE)
605 if (tree arrbnd = TYPE_DOMAIN (type))
607 if ((arrbnd = TYPE_MAX_VALUE (arrbnd)))
609 asize = wi::to_offset (arrbnd) + 1;
610 known_size = true;
613 else if (bound == void_type_node)
614 bound = NULL_TREE;
616 else if (bound == void_type_node)
617 bound = NULL_TREE;
619 /* In a call to strncat with a bound in a range whose lower but
620 not upper bound is less than the array size, reset ASIZE to
621 be the same as the bound and the other variable to trigger
622 the appropriate warning below. */
623 if (fncode == BUILT_IN_STRNCAT
624 && bndrng[0] != bndrng[1]
625 && wi::ltu_p (wi::to_offset (bndrng[0]), asize)
626 && (!known_size
627 || wi::ltu_p (asize, wibnd)))
629 asize = wibnd;
630 bound = NULL_TREE;
631 fncode = 0;
634 bool warned = false;
636 auto_diagnostic_group d;
637 if (wi::ltu_p (asize, wibnd))
639 if (bndrng[0] == bndrng[1])
640 warned = warning_at (loc, OPT_Wstringop_overread,
641 "%qD argument %i declared attribute "
642 "%<nonstring%> is smaller than the specified "
643 "bound %wu",
644 fndecl, argno + 1, wibnd.to_uhwi ());
645 else if (wi::ltu_p (asize, wi::to_offset (bndrng[0])))
646 warned = warning_at (loc, OPT_Wstringop_overread,
647 "%qD argument %i declared attribute "
648 "%<nonstring%> is smaller than "
649 "the specified bound [%E, %E]",
650 fndecl, argno + 1, bndrng[0], bndrng[1]);
651 else
652 warned = warning_at (loc, OPT_Wstringop_overread,
653 "%qD argument %i declared attribute "
654 "%<nonstring%> may be smaller than "
655 "the specified bound [%E, %E]",
656 fndecl, argno + 1, bndrng[0], bndrng[1]);
658 else if (fncode == BUILT_IN_STRNCAT)
659 ; /* Avoid warning for calls to strncat() when the bound
660 is equal to the size of the non-string argument. */
661 else if (!bound)
662 warned = warning_at (loc, OPT_Wstringop_overread,
663 "%qD argument %i declared attribute %<nonstring%>",
664 fndecl, argno + 1);
666 if (warned)
668 inform (DECL_SOURCE_LOCATION (decl),
669 "argument %qD declared here", decl);
670 any_arg_warned = true;
674 if (any_arg_warned)
675 suppress_warning (exp, OPT_Wstringop_overread);
677 return any_arg_warned;
680 bool
681 maybe_warn_nonstring_arg (tree fndecl, gimple *stmt)
683 return maybe_warn_nonstring_arg<gimple *>(fndecl, stmt);
687 bool
688 maybe_warn_nonstring_arg (tree fndecl, tree expr)
690 return maybe_warn_nonstring_arg<tree>(fndecl, expr);
693 /* Issue a warning OPT for a bounded call EXP with a bound in RANGE
694 accessing an object with SIZE. */
696 template <class GimpleOrTree>
697 static bool
698 maybe_warn_for_bound (opt_code opt, location_t loc, GimpleOrTree exp, tree func,
699 tree bndrng[2], tree size, const access_data *pad)
701 if (!bndrng[0] || warning_suppressed_p (exp, opt))
702 return false;
704 tree maxobjsize = max_object_size ();
706 bool warned = false;
708 if (opt == OPT_Wstringop_overread)
710 bool maybe = pad && pad->src.phi ();
711 if (maybe)
713 /* Issue a "maybe" warning only if the PHI refers to objects
714 at least one of which has more space remaining than the bound.
715 Otherwise, if the bound is greater, use the definitive form. */
716 offset_int remmax = pad->src.size_remaining ();
717 if (remmax < wi::to_offset (bndrng[0]))
718 maybe = false;
721 if (tree_int_cst_lt (maxobjsize, bndrng[0]))
723 if (bndrng[0] == bndrng[1])
724 warned = (func
725 ? warning_at (loc, opt,
726 (maybe
727 ? G_("%qD specified bound %E may "
728 "exceed maximum object size %E")
729 : G_("%qD specified bound %E "
730 "exceeds maximum object size %E")),
731 func, bndrng[0], maxobjsize)
732 : warning_at (loc, opt,
733 (maybe
734 ? G_("specified bound %E may "
735 "exceed maximum object size %E")
736 : G_("specified bound %E "
737 "exceeds maximum object size %E")),
738 bndrng[0], maxobjsize));
739 else
740 warned = (func
741 ? warning_at (loc, opt,
742 (maybe
743 ? G_("%qD specified bound [%E, %E] may "
744 "exceed maximum object size %E")
745 : G_("%qD specified bound [%E, %E] "
746 "exceeds maximum object size %E")),
747 func,
748 bndrng[0], bndrng[1], maxobjsize)
749 : warning_at (loc, opt,
750 (maybe
751 ? G_("specified bound [%E, %E] may "
752 "exceed maximum object size %E")
753 : G_("specified bound [%E, %E] "
754 "exceeds maximum object size %E")),
755 bndrng[0], bndrng[1], maxobjsize));
757 else if (!size || tree_int_cst_le (bndrng[0], size))
758 return false;
759 else if (tree_int_cst_equal (bndrng[0], bndrng[1]))
760 warned = (func
761 ? warning_at (loc, opt,
762 (maybe
763 ? G_("%qD specified bound %E may exceed "
764 "source size %E")
765 : G_("%qD specified bound %E exceeds "
766 "source size %E")),
767 func, bndrng[0], size)
768 : warning_at (loc, opt,
769 (maybe
770 ? G_("specified bound %E may exceed "
771 "source size %E")
772 : G_("specified bound %E exceeds "
773 "source size %E")),
774 bndrng[0], size));
775 else
776 warned = (func
777 ? warning_at (loc, opt,
778 (maybe
779 ? G_("%qD specified bound [%E, %E] may "
780 "exceed source size %E")
781 : G_("%qD specified bound [%E, %E] exceeds "
782 "source size %E")),
783 func, bndrng[0], bndrng[1], size)
784 : warning_at (loc, opt,
785 (maybe
786 ? G_("specified bound [%E, %E] may exceed "
787 "source size %E")
788 : G_("specified bound [%E, %E] exceeds "
789 "source size %E")),
790 bndrng[0], bndrng[1], size));
791 if (warned)
793 if (pad && pad->src.ref
794 && has_location (pad->src.ref))
795 inform (get_location (pad->src.ref),
796 "source object allocated here");
797 suppress_warning (exp, opt);
800 return warned;
803 bool maybe = pad && pad->dst.phi ();
804 if (maybe)
806 /* Issue a "maybe" warning only if the PHI refers to objects
807 at least one of which has more space remaining than the bound.
808 Otherwise, if the bound is greater, use the definitive form. */
809 offset_int remmax = pad->dst.size_remaining ();
810 if (remmax < wi::to_offset (bndrng[0]))
811 maybe = false;
813 if (tree_int_cst_lt (maxobjsize, bndrng[0]))
815 if (bndrng[0] == bndrng[1])
816 warned = (func
817 ? warning_at (loc, opt,
818 (maybe
819 ? G_("%qD specified size %E may "
820 "exceed maximum object size %E")
821 : G_("%qD specified size %E "
822 "exceeds maximum object size %E")),
823 func, bndrng[0], maxobjsize)
824 : warning_at (loc, opt,
825 (maybe
826 ? G_("specified size %E may exceed "
827 "maximum object size %E")
828 : G_("specified size %E exceeds "
829 "maximum object size %E")),
830 bndrng[0], maxobjsize));
831 else
832 warned = (func
833 ? warning_at (loc, opt,
834 (maybe
835 ? G_("%qD specified size between %E and %E "
836 "may exceed maximum object size %E")
837 : G_("%qD specified size between %E and %E "
838 "exceeds maximum object size %E")),
839 func, bndrng[0], bndrng[1], maxobjsize)
840 : warning_at (loc, opt,
841 (maybe
842 ? G_("specified size between %E and %E "
843 "may exceed maximum object size %E")
844 : G_("specified size between %E and %E "
845 "exceeds maximum object size %E")),
846 bndrng[0], bndrng[1], maxobjsize));
848 else if (!size || tree_int_cst_le (bndrng[0], size))
849 return false;
850 else if (tree_int_cst_equal (bndrng[0], bndrng[1]))
851 warned = (func
852 ? warning_at (loc, opt,
853 (maybe
854 ? G_("%qD specified bound %E may exceed "
855 "destination size %E")
856 : G_("%qD specified bound %E exceeds "
857 "destination size %E")),
858 func, bndrng[0], size)
859 : warning_at (loc, opt,
860 (maybe
861 ? G_("specified bound %E may exceed "
862 "destination size %E")
863 : G_("specified bound %E exceeds "
864 "destination size %E")),
865 bndrng[0], size));
866 else
867 warned = (func
868 ? warning_at (loc, opt,
869 (maybe
870 ? G_("%qD specified bound [%E, %E] may exceed "
871 "destination size %E")
872 : G_("%qD specified bound [%E, %E] exceeds "
873 "destination size %E")),
874 func, bndrng[0], bndrng[1], size)
875 : warning_at (loc, opt,
876 (maybe
877 ? G_("specified bound [%E, %E] exceeds "
878 "destination size %E")
879 : G_("specified bound [%E, %E] exceeds "
880 "destination size %E")),
881 bndrng[0], bndrng[1], size));
883 if (warned)
885 if (pad && pad->dst.ref
886 && has_location (pad->dst.ref))
887 inform (get_location (pad->dst.ref),
888 "destination object allocated here");
889 suppress_warning (exp, opt);
892 return warned;
895 bool
896 maybe_warn_for_bound (opt_code opt, location_t loc, gimple *stmt, tree func,
897 tree bndrng[2], tree size,
898 const access_data *pad /* = NULL */)
900 return maybe_warn_for_bound<gimple *> (opt, loc, stmt, func, bndrng, size,
901 pad);
904 bool
905 maybe_warn_for_bound (opt_code opt, location_t loc, tree expr, tree func,
906 tree bndrng[2], tree size,
907 const access_data *pad /* = NULL */)
909 return maybe_warn_for_bound<tree> (opt, loc, expr, func, bndrng, size, pad);
912 /* For an expression EXP issue an access warning controlled by option OPT
913 with access to a region SIZE bytes in size in the RANGE of sizes.
914 WRITE is true for a write access, READ for a read access, neither for
915 call that may or may not perform an access but for which the range
916 is expected to valid.
917 Returns true when a warning has been issued. */
919 template <class GimpleOrTree>
920 static bool
921 warn_for_access (location_t loc, tree func, GimpleOrTree exp, int opt,
922 tree range[2], tree size, bool write, bool read, bool maybe)
924 bool warned = false;
926 if (write && read)
928 if (tree_int_cst_equal (range[0], range[1]))
929 warned = (func
930 ? warning_n (loc, opt, tree_to_uhwi (range[0]),
931 (maybe
932 ? G_("%qD may access %E byte in a region "
933 "of size %E")
934 : G_("%qD accessing %E byte in a region "
935 "of size %E")),
936 (maybe
937 ? G_ ("%qD may access %E bytes in a region "
938 "of size %E")
939 : G_ ("%qD accessing %E bytes in a region "
940 "of size %E")),
941 func, range[0], size)
942 : warning_n (loc, opt, tree_to_uhwi (range[0]),
943 (maybe
944 ? G_("may access %E byte in a region "
945 "of size %E")
946 : G_("accessing %E byte in a region "
947 "of size %E")),
948 (maybe
949 ? G_("may access %E bytes in a region "
950 "of size %E")
951 : G_("accessing %E bytes in a region "
952 "of size %E")),
953 range[0], size));
954 else if (tree_int_cst_sign_bit (range[1]))
956 /* Avoid printing the upper bound if it's invalid. */
957 warned = (func
958 ? warning_at (loc, opt,
959 (maybe
960 ? G_("%qD may access %E or more bytes "
961 "in a region of size %E")
962 : G_("%qD accessing %E or more bytes "
963 "in a region of size %E")),
964 func, range[0], size)
965 : warning_at (loc, opt,
966 (maybe
967 ? G_("may access %E or more bytes "
968 "in a region of size %E")
969 : G_("accessing %E or more bytes "
970 "in a region of size %E")),
971 range[0], size));
973 else
974 warned = (func
975 ? warning_at (loc, opt,
976 (maybe
977 ? G_("%qD may access between %E and %E "
978 "bytes in a region of size %E")
979 : G_("%qD accessing between %E and %E "
980 "bytes in a region of size %E")),
981 func, range[0], range[1], size)
982 : warning_at (loc, opt,
983 (maybe
984 ? G_("may access between %E and %E bytes "
985 "in a region of size %E")
986 : G_("accessing between %E and %E bytes "
987 "in a region of size %E")),
988 range[0], range[1], size));
989 return warned;
992 if (write)
994 if (tree_int_cst_equal (range[0], range[1]))
995 warned = (func
996 ? warning_n (loc, opt, tree_to_uhwi (range[0]),
997 (maybe
998 ? G_("%qD may write %E byte into a region "
999 "of size %E")
1000 : G_("%qD writing %E byte into a region "
1001 "of size %E overflows the destination")),
1002 (maybe
1003 ? G_("%qD may write %E bytes into a region "
1004 "of size %E")
1005 : G_("%qD writing %E bytes into a region "
1006 "of size %E overflows the destination")),
1007 func, range[0], size)
1008 : warning_n (loc, opt, tree_to_uhwi (range[0]),
1009 (maybe
1010 ? G_("may write %E byte into a region "
1011 "of size %E")
1012 : G_("writing %E byte into a region "
1013 "of size %E overflows the destination")),
1014 (maybe
1015 ? G_("may write %E bytes into a region "
1016 "of size %E")
1017 : G_("writing %E bytes into a region "
1018 "of size %E overflows the destination")),
1019 range[0], size));
1020 else if (tree_int_cst_sign_bit (range[1]))
1022 /* Avoid printing the upper bound if it's invalid. */
1023 warned = (func
1024 ? warning_at (loc, opt,
1025 (maybe
1026 ? G_("%qD may write %E or more bytes "
1027 "into a region of size %E")
1028 : G_("%qD writing %E or more bytes "
1029 "into a region of size %E overflows "
1030 "the destination")),
1031 func, range[0], size)
1032 : warning_at (loc, opt,
1033 (maybe
1034 ? G_("may write %E or more bytes into "
1035 "a region of size %E")
1036 : G_("writing %E or more bytes into "
1037 "a region of size %E overflows "
1038 "the destination")),
1039 range[0], size));
1041 else
1042 warned = (func
1043 ? warning_at (loc, opt,
1044 (maybe
1045 ? G_("%qD may write between %E and %E bytes "
1046 "into a region of size %E")
1047 : G_("%qD writing between %E and %E bytes "
1048 "into a region of size %E overflows "
1049 "the destination")),
1050 func, range[0], range[1], size)
1051 : warning_at (loc, opt,
1052 (maybe
1053 ? G_("may write between %E and %E bytes "
1054 "into a region of size %E")
1055 : G_("writing between %E and %E bytes "
1056 "into a region of size %E overflows "
1057 "the destination")),
1058 range[0], range[1], size));
1059 return warned;
1062 if (read)
1064 if (tree_int_cst_equal (range[0], range[1]))
1065 warned = (func
1066 ? warning_n (loc, OPT_Wstringop_overread,
1067 tree_to_uhwi (range[0]),
1068 (maybe
1069 ? G_("%qD may read %E byte from a region "
1070 "of size %E")
1071 : G_("%qD reading %E byte from a region "
1072 "of size %E")),
1073 (maybe
1074 ? G_("%qD may read %E bytes from a region "
1075 "of size %E")
1076 : G_("%qD reading %E bytes from a region "
1077 "of size %E")),
1078 func, range[0], size)
1079 : warning_n (loc, OPT_Wstringop_overread,
1080 tree_to_uhwi (range[0]),
1081 (maybe
1082 ? G_("may read %E byte from a region "
1083 "of size %E")
1084 : G_("reading %E byte from a region "
1085 "of size %E")),
1086 (maybe
1087 ? G_("may read %E bytes from a region "
1088 "of size %E")
1089 : G_("reading %E bytes from a region "
1090 "of size %E")),
1091 range[0], size));
1092 else if (tree_int_cst_sign_bit (range[1]))
1094 /* Avoid printing the upper bound if it's invalid. */
1095 warned = (func
1096 ? warning_at (loc, OPT_Wstringop_overread,
1097 (maybe
1098 ? G_("%qD may read %E or more bytes "
1099 "from a region of size %E")
1100 : G_("%qD reading %E or more bytes "
1101 "from a region of size %E")),
1102 func, range[0], size)
1103 : warning_at (loc, OPT_Wstringop_overread,
1104 (maybe
1105 ? G_("may read %E or more bytes "
1106 "from a region of size %E")
1107 : G_("reading %E or more bytes "
1108 "from a region of size %E")),
1109 range[0], size));
1111 else
1112 warned = (func
1113 ? warning_at (loc, OPT_Wstringop_overread,
1114 (maybe
1115 ? G_("%qD may read between %E and %E bytes "
1116 "from a region of size %E")
1117 : G_("%qD reading between %E and %E bytes "
1118 "from a region of size %E")),
1119 func, range[0], range[1], size)
1120 : warning_at (loc, opt,
1121 (maybe
1122 ? G_("may read between %E and %E bytes "
1123 "from a region of size %E")
1124 : G_("reading between %E and %E bytes "
1125 "from a region of size %E")),
1126 range[0], range[1], size));
1128 if (warned)
1129 suppress_warning (exp, OPT_Wstringop_overread);
1131 return warned;
1134 if (tree_int_cst_equal (range[0], range[1])
1135 || tree_int_cst_sign_bit (range[1]))
1136 warned = (func
1137 ? warning_n (loc, OPT_Wstringop_overread,
1138 tree_to_uhwi (range[0]),
1139 "%qD expecting %E byte in a region of size %E",
1140 "%qD expecting %E bytes in a region of size %E",
1141 func, range[0], size)
1142 : warning_n (loc, OPT_Wstringop_overread,
1143 tree_to_uhwi (range[0]),
1144 "expecting %E byte in a region of size %E",
1145 "expecting %E bytes in a region of size %E",
1146 range[0], size));
1147 else if (tree_int_cst_sign_bit (range[1]))
1149 /* Avoid printing the upper bound if it's invalid. */
1150 warned = (func
1151 ? warning_at (loc, OPT_Wstringop_overread,
1152 "%qD expecting %E or more bytes in a region "
1153 "of size %E",
1154 func, range[0], size)
1155 : warning_at (loc, OPT_Wstringop_overread,
1156 "expecting %E or more bytes in a region "
1157 "of size %E",
1158 range[0], size));
1160 else
1161 warned = (func
1162 ? warning_at (loc, OPT_Wstringop_overread,
1163 "%qD expecting between %E and %E bytes in "
1164 "a region of size %E",
1165 func, range[0], range[1], size)
1166 : warning_at (loc, OPT_Wstringop_overread,
1167 "expecting between %E and %E bytes in "
1168 "a region of size %E",
1169 range[0], range[1], size));
1171 if (warned)
1172 suppress_warning (exp, OPT_Wstringop_overread);
1174 return warned;
1177 static bool
1178 warn_for_access (location_t loc, tree func, gimple *stmt, int opt,
1179 tree range[2], tree size, bool write, bool read, bool maybe)
1181 return warn_for_access<gimple *>(loc, func, stmt, opt, range, size,
1182 write, read, maybe);
1185 static bool
1186 warn_for_access (location_t loc, tree func, tree expr, int opt,
1187 tree range[2], tree size, bool write, bool read, bool maybe)
1189 return warn_for_access<tree>(loc, func, expr, opt, range, size,
1190 write, read, maybe);
1193 /* Helper to set RANGE to the range of BOUND if it's nonnull, bounded
1194 by BNDRNG if nonnull and valid. */
1196 static void
1197 get_size_range (range_query *query, tree bound, gimple *stmt, tree range[2],
1198 const offset_int bndrng[2])
1200 if (bound)
1201 get_size_range (query, bound, stmt, range);
1203 if (!bndrng || (bndrng[0] == 0 && bndrng[1] == HOST_WIDE_INT_M1U))
1204 return;
1206 if (range[0] && TREE_CODE (range[0]) == INTEGER_CST)
1208 offset_int r[] =
1209 { wi::to_offset (range[0]), wi::to_offset (range[1]) };
1210 if (r[0] < bndrng[0])
1211 range[0] = wide_int_to_tree (sizetype, bndrng[0]);
1212 if (bndrng[1] < r[1])
1213 range[1] = wide_int_to_tree (sizetype, bndrng[1]);
1215 else
1217 range[0] = wide_int_to_tree (sizetype, bndrng[0]);
1218 range[1] = wide_int_to_tree (sizetype, bndrng[1]);
1222 /* Try to verify that the sizes and lengths of the arguments to a string
1223 manipulation function given by EXP are within valid bounds and that
1224 the operation does not lead to buffer overflow or read past the end.
1225 Arguments other than EXP may be null. When non-null, the arguments
1226 have the following meaning:
1227 DST is the destination of a copy call or NULL otherwise.
1228 SRC is the source of a copy call or NULL otherwise.
1229 DSTWRITE is the number of bytes written into the destination obtained
1230 from the user-supplied size argument to the function (such as in
1231 memcpy(DST, SRCs, DSTWRITE) or strncpy(DST, DRC, DSTWRITE).
1232 MAXREAD is the user-supplied bound on the length of the source sequence
1233 (such as in strncat(d, s, N). It specifies the upper limit on the number
1234 of bytes to write. If NULL, it's taken to be the same as DSTWRITE.
1235 SRCSTR is the source string (such as in strcpy(DST, SRC)) when the
1236 expression EXP is a string function call (as opposed to a memory call
1237 like memcpy). As an exception, SRCSTR can also be an integer denoting
1238 the precomputed size of the source string or object (for functions like
1239 memcpy).
1240 DSTSIZE is the size of the destination object.
1242 When DSTWRITE is null LEN is checked to verify that it doesn't exceed
1243 SIZE_MAX.
1245 WRITE is true for write accesses, READ is true for reads. Both are
1246 false for simple size checks in calls to functions that neither read
1247 from nor write to the region.
1249 When nonnull, PAD points to a more detailed description of the access.
1251 If the call is successfully verified as safe return true, otherwise
1252 return false. */
1254 template <class GimpleOrTree>
1255 static bool
1256 check_access (GimpleOrTree exp, tree dstwrite,
1257 tree maxread, tree srcstr, tree dstsize,
1258 access_mode mode, const access_data *pad,
1259 range_query *rvals)
1261 /* The size of the largest object is half the address space, or
1262 PTRDIFF_MAX. (This is way too permissive.) */
1263 tree maxobjsize = max_object_size ();
1265 /* Either an approximate/minimum the length of the source string for
1266 string functions or the size of the source object for raw memory
1267 functions. */
1268 tree slen = NULL_TREE;
1270 /* The range of the access in bytes; first set to the write access
1271 for functions that write and then read for those that also (or
1272 just) read. */
1273 tree range[2] = { NULL_TREE, NULL_TREE };
1275 /* Set to true when the exact number of bytes written by a string
1276 function like strcpy is not known and the only thing that is
1277 known is that it must be at least one (for the terminating nul). */
1278 bool at_least_one = false;
1279 if (srcstr)
1281 /* SRCSTR is normally a pointer to string but as a special case
1282 it can be an integer denoting the length of a string. */
1283 if (POINTER_TYPE_P (TREE_TYPE (srcstr)))
1285 if (!check_nul_terminated_array (exp, srcstr, maxread))
1286 /* Return if the array is not nul-terminated and a warning
1287 has been issued. */
1288 return false;
1290 /* Try to determine the range of lengths the source string
1291 refers to. If it can be determined and is less than
1292 the upper bound given by MAXREAD add one to it for
1293 the terminating nul. Otherwise, set it to one for
1294 the same reason, or to MAXREAD as appropriate. */
1295 c_strlen_data lendata = { };
1296 get_range_strlen (srcstr, &lendata, /* eltsize = */ 1);
1297 range[0] = lendata.minlen;
1298 range[1] = lendata.maxbound ? lendata.maxbound : lendata.maxlen;
1299 if (range[0]
1300 && TREE_CODE (range[0]) == INTEGER_CST
1301 && TREE_CODE (range[1]) == INTEGER_CST
1302 && (!maxread || TREE_CODE (maxread) == INTEGER_CST))
1304 if (maxread && tree_int_cst_le (maxread, range[0]))
1305 range[0] = range[1] = maxread;
1306 else
1307 range[0] = fold_build2 (PLUS_EXPR, size_type_node,
1308 range[0], size_one_node);
1310 if (maxread && tree_int_cst_le (maxread, range[1]))
1311 range[1] = maxread;
1312 else if (!integer_all_onesp (range[1]))
1313 range[1] = fold_build2 (PLUS_EXPR, size_type_node,
1314 range[1], size_one_node);
1316 slen = range[0];
1318 else
1320 at_least_one = true;
1321 slen = size_one_node;
1324 else
1325 slen = srcstr;
1328 if (!dstwrite && !maxread)
1330 /* When the only available piece of data is the object size
1331 there is nothing to do. */
1332 if (!slen)
1333 return true;
1335 /* Otherwise, when the length of the source sequence is known
1336 (as with strlen), set DSTWRITE to it. */
1337 if (!range[0])
1338 dstwrite = slen;
1341 if (!dstsize)
1342 dstsize = maxobjsize;
1344 /* Set RANGE to that of DSTWRITE if non-null, bounded by PAD->DST_BNDRNG
1345 if valid. */
1346 gimple *stmt = pad ? pad->stmt : nullptr;
1347 get_size_range (rvals, dstwrite, stmt, range, pad ? pad->dst_bndrng : NULL);
1349 tree func = get_callee_fndecl (exp);
1350 /* Read vs write access by built-ins can be determined from the const
1351 qualifiers on the pointer argument. In the absence of attribute
1352 access, non-const qualified pointer arguments to user-defined
1353 functions are assumed to both read and write the objects. */
1354 const bool builtin = func ? fndecl_built_in_p (func) : false;
1356 /* First check the number of bytes to be written against the maximum
1357 object size. */
1358 if (range[0]
1359 && TREE_CODE (range[0]) == INTEGER_CST
1360 && tree_int_cst_lt (maxobjsize, range[0]))
1362 location_t loc = get_location (exp);
1363 maybe_warn_for_bound (OPT_Wstringop_overflow_, loc, exp, func, range,
1364 NULL_TREE, pad);
1365 return false;
1368 /* The number of bytes to write is "exact" if DSTWRITE is non-null,
1369 constant, and in range of unsigned HOST_WIDE_INT. */
1370 bool exactwrite = dstwrite && tree_fits_uhwi_p (dstwrite);
1372 /* Next check the number of bytes to be written against the destination
1373 object size. */
1374 if (range[0] || !exactwrite || integer_all_onesp (dstwrite))
1376 if (range[0]
1377 && TREE_CODE (range[0]) == INTEGER_CST
1378 && ((tree_fits_uhwi_p (dstsize)
1379 && tree_int_cst_lt (dstsize, range[0]))
1380 || (dstwrite
1381 && tree_fits_uhwi_p (dstwrite)
1382 && tree_int_cst_lt (dstwrite, range[0]))))
1384 const opt_code opt = OPT_Wstringop_overflow_;
1385 if (warning_suppressed_p (exp, opt)
1386 || (pad && pad->dst.ref
1387 && warning_suppressed_p (pad->dst.ref, opt)))
1388 return false;
1390 location_t loc = get_location (exp);
1391 bool warned = false;
1392 if (dstwrite == slen && at_least_one)
1394 /* This is a call to strcpy with a destination of 0 size
1395 and a source of unknown length. The call will write
1396 at least one byte past the end of the destination. */
1397 warned = (func
1398 ? warning_at (loc, opt,
1399 "%qD writing %E or more bytes into "
1400 "a region of size %E overflows "
1401 "the destination",
1402 func, range[0], dstsize)
1403 : warning_at (loc, opt,
1404 "writing %E or more bytes into "
1405 "a region of size %E overflows "
1406 "the destination",
1407 range[0], dstsize));
1409 else
1411 const bool read
1412 = mode == access_read_only || mode == access_read_write;
1413 const bool write
1414 = mode == access_write_only || mode == access_read_write;
1415 const bool maybe = pad && pad->dst.parmarray;
1416 warned = warn_for_access (loc, func, exp,
1417 OPT_Wstringop_overflow_,
1418 range, dstsize,
1419 write, read && !builtin, maybe);
1422 if (warned)
1424 suppress_warning (exp, OPT_Wstringop_overflow_);
1425 if (pad)
1426 pad->dst.inform_access (pad->mode);
1429 /* Return error when an overflow has been detected. */
1430 return false;
1434 /* Check the maximum length of the source sequence against the size
1435 of the destination object if known, or against the maximum size
1436 of an object. */
1437 if (maxread)
1439 /* Set RANGE to that of MAXREAD, bounded by PAD->SRC_BNDRNG if
1440 PAD is nonnull and BNDRNG is valid. */
1441 get_size_range (rvals, maxread, stmt, range, pad ? pad->src_bndrng : NULL);
1443 location_t loc = get_location (exp);
1444 tree size = dstsize;
1445 if (pad && pad->mode == access_read_only)
1446 size = wide_int_to_tree (sizetype, pad->src.size_remaining ());
1448 if (range[0] && maxread && tree_fits_uhwi_p (size))
1450 if (tree_int_cst_lt (maxobjsize, range[0]))
1452 maybe_warn_for_bound (OPT_Wstringop_overread, loc, exp, func,
1453 range, size, pad);
1454 return false;
1457 if (size != maxobjsize && tree_int_cst_lt (size, range[0]))
1459 opt_code opt = (dstwrite || mode != access_read_only
1460 ? OPT_Wstringop_overflow_
1461 : OPT_Wstringop_overread);
1462 maybe_warn_for_bound (opt, loc, exp, func, range, size, pad);
1463 return false;
1467 maybe_warn_nonstring_arg (func, exp);
1470 /* Check for reading past the end of SRC. */
1471 bool overread = (slen
1472 && slen == srcstr
1473 && dstwrite
1474 && range[0]
1475 && TREE_CODE (slen) == INTEGER_CST
1476 && tree_int_cst_lt (slen, range[0]));
1477 /* If none is determined try to get a better answer based on the details
1478 in PAD. */
1479 if (!overread
1480 && pad
1481 && pad->src.sizrng[1] >= 0
1482 && pad->src.offrng[0] >= 0
1483 && (pad->src.offrng[1] < 0
1484 || pad->src.offrng[0] <= pad->src.offrng[1]))
1486 /* Set RANGE to that of MAXREAD, bounded by PAD->SRC_BNDRNG if
1487 PAD is nonnull and BNDRNG is valid. */
1488 get_size_range (rvals, maxread, stmt, range, pad ? pad->src_bndrng : NULL);
1489 /* Set OVERREAD for reads starting just past the end of an object. */
1490 overread = pad->src.sizrng[1] - pad->src.offrng[0] < pad->src_bndrng[0];
1491 range[0] = wide_int_to_tree (sizetype, pad->src_bndrng[0]);
1492 slen = size_zero_node;
1495 if (overread)
1497 const opt_code opt = OPT_Wstringop_overread;
1498 if (warning_suppressed_p (exp, opt)
1499 || (srcstr && warning_suppressed_p (srcstr, opt))
1500 || (pad && pad->src.ref
1501 && warning_suppressed_p (pad->src.ref, opt)))
1502 return false;
1504 location_t loc = get_location (exp);
1505 const bool read
1506 = mode == access_read_only || mode == access_read_write;
1507 const bool maybe = pad && pad->dst.parmarray;
1508 if (warn_for_access (loc, func, exp, opt, range, slen, false, read,
1509 maybe))
1511 suppress_warning (exp, opt);
1512 if (pad)
1513 pad->src.inform_access (access_read_only);
1515 return false;
1518 return true;
1521 static bool
1522 check_access (gimple *stmt, tree dstwrite,
1523 tree maxread, tree srcstr, tree dstsize,
1524 access_mode mode, const access_data *pad,
1525 range_query *rvals)
1527 return check_access<gimple *> (stmt, dstwrite, maxread, srcstr, dstsize,
1528 mode, pad, rvals);
1531 bool
1532 check_access (tree expr, tree dstwrite,
1533 tree maxread, tree srcstr, tree dstsize,
1534 access_mode mode, const access_data *pad /* = NULL */)
1536 return check_access<tree> (expr, dstwrite, maxread, srcstr, dstsize,
1537 mode, pad, nullptr);
1540 /* Return true if STMT is a call to an allocation function. Unless
1541 ALL_ALLOC is set, consider only functions that return dynamically
1542 allocated objects. Otherwise return true even for all forms of
1543 alloca (including VLA). */
1545 static bool
1546 fndecl_alloc_p (tree fndecl, bool all_alloc)
1548 if (!fndecl)
1549 return false;
1551 /* A call to operator new isn't recognized as one to a built-in. */
1552 if (DECL_IS_OPERATOR_NEW_P (fndecl))
1553 return true;
1555 if (fndecl_built_in_p (fndecl, BUILT_IN_NORMAL))
1557 switch (DECL_FUNCTION_CODE (fndecl))
1559 case BUILT_IN_ALLOCA:
1560 case BUILT_IN_ALLOCA_WITH_ALIGN:
1561 return all_alloc;
1562 case BUILT_IN_ALIGNED_ALLOC:
1563 case BUILT_IN_CALLOC:
1564 case BUILT_IN_GOMP_ALLOC:
1565 case BUILT_IN_MALLOC:
1566 case BUILT_IN_REALLOC:
1567 case BUILT_IN_STRDUP:
1568 case BUILT_IN_STRNDUP:
1569 return true;
1570 default:
1571 break;
1575 /* A function is considered an allocation function if it's declared
1576 with attribute malloc with an argument naming its associated
1577 deallocation function. */
1578 tree attrs = DECL_ATTRIBUTES (fndecl);
1579 if (!attrs)
1580 return false;
1582 for (tree allocs = attrs;
1583 (allocs = lookup_attribute ("malloc", allocs));
1584 allocs = TREE_CHAIN (allocs))
1586 tree args = TREE_VALUE (allocs);
1587 if (!args)
1588 continue;
1590 if (TREE_VALUE (args))
1591 return true;
1594 return false;
1597 /* Return true if STMT is a call to an allocation function. A wrapper
1598 around fndecl_alloc_p. */
1600 static bool
1601 gimple_call_alloc_p (gimple *stmt, bool all_alloc = false)
1603 return fndecl_alloc_p (gimple_call_fndecl (stmt), all_alloc);
1606 /* Return true if DELC doesn't refer to an operator delete that's
1607 suitable to call with a pointer returned from the operator new
1608 described by NEWC. */
1610 static bool
1611 new_delete_mismatch_p (const demangle_component &newc,
1612 const demangle_component &delc)
1614 if (newc.type != delc.type)
1615 return true;
1617 switch (newc.type)
1619 case DEMANGLE_COMPONENT_NAME:
1621 int len = newc.u.s_name.len;
1622 const char *news = newc.u.s_name.s;
1623 const char *dels = delc.u.s_name.s;
1624 if (len != delc.u.s_name.len || memcmp (news, dels, len))
1625 return true;
1627 if (news[len] == 'n')
1629 if (news[len + 1] == 'a')
1630 return dels[len] != 'd' || dels[len + 1] != 'a';
1631 if (news[len + 1] == 'w')
1632 return dels[len] != 'd' || dels[len + 1] != 'l';
1634 return false;
1637 case DEMANGLE_COMPONENT_OPERATOR:
1638 /* Operator mismatches are handled above. */
1639 return false;
1641 case DEMANGLE_COMPONENT_EXTENDED_OPERATOR:
1642 if (newc.u.s_extended_operator.args != delc.u.s_extended_operator.args)
1643 return true;
1644 return new_delete_mismatch_p (*newc.u.s_extended_operator.name,
1645 *delc.u.s_extended_operator.name);
1647 case DEMANGLE_COMPONENT_FIXED_TYPE:
1648 if (newc.u.s_fixed.accum != delc.u.s_fixed.accum
1649 || newc.u.s_fixed.sat != delc.u.s_fixed.sat)
1650 return true;
1651 return new_delete_mismatch_p (*newc.u.s_fixed.length,
1652 *delc.u.s_fixed.length);
1654 case DEMANGLE_COMPONENT_CTOR:
1655 if (newc.u.s_ctor.kind != delc.u.s_ctor.kind)
1656 return true;
1657 return new_delete_mismatch_p (*newc.u.s_ctor.name,
1658 *delc.u.s_ctor.name);
1660 case DEMANGLE_COMPONENT_DTOR:
1661 if (newc.u.s_dtor.kind != delc.u.s_dtor.kind)
1662 return true;
1663 return new_delete_mismatch_p (*newc.u.s_dtor.name,
1664 *delc.u.s_dtor.name);
1666 case DEMANGLE_COMPONENT_BUILTIN_TYPE:
1668 /* The demangler API provides no better way to compare built-in
1669 types except to by comparing their demangled names. */
1670 size_t nsz, dsz;
1671 demangle_component *pnc = const_cast<demangle_component *>(&newc);
1672 demangle_component *pdc = const_cast<demangle_component *>(&delc);
1673 char *nts = cplus_demangle_print (0, pnc, 16, &nsz);
1674 char *dts = cplus_demangle_print (0, pdc, 16, &dsz);
1675 if (!nts != !dts)
1676 return true;
1677 bool mismatch = strcmp (nts, dts);
1678 free (nts);
1679 free (dts);
1680 return mismatch;
1683 case DEMANGLE_COMPONENT_SUB_STD:
1684 if (newc.u.s_string.len != delc.u.s_string.len)
1685 return true;
1686 return memcmp (newc.u.s_string.string, delc.u.s_string.string,
1687 newc.u.s_string.len);
1689 case DEMANGLE_COMPONENT_FUNCTION_PARAM:
1690 case DEMANGLE_COMPONENT_TEMPLATE_PARAM:
1691 return newc.u.s_number.number != delc.u.s_number.number;
1693 case DEMANGLE_COMPONENT_CHARACTER:
1694 return newc.u.s_character.character != delc.u.s_character.character;
1696 case DEMANGLE_COMPONENT_DEFAULT_ARG:
1697 case DEMANGLE_COMPONENT_LAMBDA:
1698 if (newc.u.s_unary_num.num != delc.u.s_unary_num.num)
1699 return true;
1700 return new_delete_mismatch_p (*newc.u.s_unary_num.sub,
1701 *delc.u.s_unary_num.sub);
1702 default:
1703 break;
1706 if (!newc.u.s_binary.left != !delc.u.s_binary.left)
1707 return true;
1709 if (!newc.u.s_binary.left)
1710 return false;
1712 if (new_delete_mismatch_p (*newc.u.s_binary.left, *delc.u.s_binary.left)
1713 || !newc.u.s_binary.right != !delc.u.s_binary.right)
1714 return true;
1716 if (newc.u.s_binary.right)
1717 return new_delete_mismatch_p (*newc.u.s_binary.right,
1718 *delc.u.s_binary.right);
1719 return false;
1722 /* Return true if DELETE_DECL is an operator delete that's not suitable
1723 to call with a pointer returned from NEW_DECL. */
1725 static bool
1726 new_delete_mismatch_p (tree new_decl, tree delete_decl)
1728 tree new_name = DECL_ASSEMBLER_NAME (new_decl);
1729 tree delete_name = DECL_ASSEMBLER_NAME (delete_decl);
1731 /* valid_new_delete_pair_p() returns a conservative result (currently
1732 it only handles global operators). A true result is reliable but
1733 a false result doesn't necessarily mean the operators don't match
1734 unless CERTAIN is set. */
1735 bool certain;
1736 if (valid_new_delete_pair_p (new_name, delete_name, &certain))
1737 return false;
1738 /* CERTAIN is set when the negative result is certain. */
1739 if (certain)
1740 return true;
1742 /* For anything not handled by valid_new_delete_pair_p() such as member
1743 operators compare the individual demangled components of the mangled
1744 name. */
1745 const char *new_str = IDENTIFIER_POINTER (new_name);
1746 const char *del_str = IDENTIFIER_POINTER (delete_name);
1748 void *np = NULL, *dp = NULL;
1749 demangle_component *ndc = cplus_demangle_v3_components (new_str, 0, &np);
1750 demangle_component *ddc = cplus_demangle_v3_components (del_str, 0, &dp);
1751 bool mismatch = new_delete_mismatch_p (*ndc, *ddc);
1752 free (np);
1753 free (dp);
1754 return mismatch;
1757 /* ALLOC_DECL and DEALLOC_DECL are pair of allocation and deallocation
1758 functions. Return true if the latter is suitable to deallocate objects
1759 allocated by calls to the former. */
1761 static bool
1762 matching_alloc_calls_p (tree alloc_decl, tree dealloc_decl)
1764 /* Set to alloc_kind_t::builtin if ALLOC_DECL is associated with
1765 a built-in deallocator. */
1766 enum class alloc_kind_t { none, builtin, user }
1767 alloc_dealloc_kind = alloc_kind_t::none;
1769 if (DECL_IS_OPERATOR_NEW_P (alloc_decl))
1771 if (DECL_IS_OPERATOR_DELETE_P (dealloc_decl))
1772 /* Return true iff both functions are of the same array or
1773 singleton form and false otherwise. */
1774 return !new_delete_mismatch_p (alloc_decl, dealloc_decl);
1776 /* Return false for deallocation functions that are known not
1777 to match. */
1778 if (fndecl_built_in_p (dealloc_decl, BUILT_IN_FREE)
1779 || fndecl_built_in_p (dealloc_decl, BUILT_IN_REALLOC))
1780 return false;
1781 /* Otherwise proceed below to check the deallocation function's
1782 "*dealloc" attributes to look for one that mentions this operator
1783 new. */
1785 else if (fndecl_built_in_p (alloc_decl, BUILT_IN_NORMAL))
1787 switch (DECL_FUNCTION_CODE (alloc_decl))
1789 case BUILT_IN_ALLOCA:
1790 case BUILT_IN_ALLOCA_WITH_ALIGN:
1791 return false;
1793 case BUILT_IN_ALIGNED_ALLOC:
1794 case BUILT_IN_CALLOC:
1795 case BUILT_IN_GOMP_ALLOC:
1796 case BUILT_IN_MALLOC:
1797 case BUILT_IN_REALLOC:
1798 case BUILT_IN_STRDUP:
1799 case BUILT_IN_STRNDUP:
1800 if (DECL_IS_OPERATOR_DELETE_P (dealloc_decl))
1801 return false;
1803 if (fndecl_built_in_p (dealloc_decl, BUILT_IN_FREE)
1804 || fndecl_built_in_p (dealloc_decl, BUILT_IN_REALLOC))
1805 return true;
1807 alloc_dealloc_kind = alloc_kind_t::builtin;
1808 break;
1810 default:
1811 break;
1815 /* Set if DEALLOC_DECL both allocates and deallocates. */
1816 alloc_kind_t realloc_kind = alloc_kind_t::none;
1818 if (fndecl_built_in_p (dealloc_decl, BUILT_IN_NORMAL))
1820 built_in_function dealloc_code = DECL_FUNCTION_CODE (dealloc_decl);
1821 if (dealloc_code == BUILT_IN_REALLOC)
1822 realloc_kind = alloc_kind_t::builtin;
1824 for (tree amats = DECL_ATTRIBUTES (alloc_decl);
1825 (amats = lookup_attribute ("malloc", amats));
1826 amats = TREE_CHAIN (amats))
1828 tree args = TREE_VALUE (amats);
1829 if (!args)
1830 continue;
1832 tree fndecl = TREE_VALUE (args);
1833 if (!fndecl || !DECL_P (fndecl))
1834 continue;
1836 if (fndecl_built_in_p (fndecl, BUILT_IN_NORMAL)
1837 && dealloc_code == DECL_FUNCTION_CODE (fndecl))
1838 return true;
1842 const bool alloc_builtin = fndecl_built_in_p (alloc_decl, BUILT_IN_NORMAL);
1843 alloc_kind_t realloc_dealloc_kind = alloc_kind_t::none;
1845 /* If DEALLOC_DECL has an internal "*dealloc" attribute scan the list
1846 of its associated allocation functions for ALLOC_DECL.
1847 If the corresponding ALLOC_DECL is found they're a matching pair,
1848 otherwise they're not.
1849 With DDATS set to the Deallocator's *Dealloc ATtributes... */
1850 for (tree ddats = DECL_ATTRIBUTES (dealloc_decl);
1851 (ddats = lookup_attribute ("*dealloc", ddats));
1852 ddats = TREE_CHAIN (ddats))
1854 tree args = TREE_VALUE (ddats);
1855 if (!args)
1856 continue;
1858 tree alloc = TREE_VALUE (args);
1859 if (!alloc)
1860 continue;
1862 if (alloc == DECL_NAME (dealloc_decl))
1863 realloc_kind = alloc_kind_t::user;
1865 if (DECL_P (alloc))
1867 gcc_checking_assert (fndecl_built_in_p (alloc, BUILT_IN_NORMAL));
1869 switch (DECL_FUNCTION_CODE (alloc))
1871 case BUILT_IN_ALIGNED_ALLOC:
1872 case BUILT_IN_CALLOC:
1873 case BUILT_IN_GOMP_ALLOC:
1874 case BUILT_IN_MALLOC:
1875 case BUILT_IN_REALLOC:
1876 case BUILT_IN_STRDUP:
1877 case BUILT_IN_STRNDUP:
1878 realloc_dealloc_kind = alloc_kind_t::builtin;
1879 break;
1880 default:
1881 break;
1884 if (!alloc_builtin)
1885 continue;
1887 if (DECL_FUNCTION_CODE (alloc) != DECL_FUNCTION_CODE (alloc_decl))
1888 continue;
1890 return true;
1893 if (alloc == DECL_NAME (alloc_decl))
1894 return true;
1897 if (realloc_kind == alloc_kind_t::none)
1898 return false;
1900 hash_set<tree> common_deallocs;
1901 /* Special handling for deallocators. Iterate over both the allocator's
1902 and the reallocator's associated deallocator functions looking for
1903 the first one in common. If one is found, the de/reallocator is
1904 a match for the allocator even though the latter isn't directly
1905 associated with the former. This simplifies declarations in system
1906 headers.
1907 With AMATS set to the Allocator's Malloc ATtributes,
1908 and RMATS set to Reallocator's Malloc ATtributes... */
1909 for (tree amats = DECL_ATTRIBUTES (alloc_decl),
1910 rmats = DECL_ATTRIBUTES (dealloc_decl);
1911 (amats = lookup_attribute ("malloc", amats))
1912 || (rmats = lookup_attribute ("malloc", rmats));
1913 amats = amats ? TREE_CHAIN (amats) : NULL_TREE,
1914 rmats = rmats ? TREE_CHAIN (rmats) : NULL_TREE)
1916 if (tree args = amats ? TREE_VALUE (amats) : NULL_TREE)
1917 if (tree adealloc = TREE_VALUE (args))
1919 if (DECL_P (adealloc)
1920 && fndecl_built_in_p (adealloc, BUILT_IN_NORMAL))
1922 built_in_function fncode = DECL_FUNCTION_CODE (adealloc);
1923 if (fncode == BUILT_IN_FREE || fncode == BUILT_IN_REALLOC)
1925 if (realloc_kind == alloc_kind_t::builtin)
1926 return true;
1927 alloc_dealloc_kind = alloc_kind_t::builtin;
1929 continue;
1932 common_deallocs.add (adealloc);
1935 if (tree args = rmats ? TREE_VALUE (rmats) : NULL_TREE)
1936 if (tree ddealloc = TREE_VALUE (args))
1938 if (DECL_P (ddealloc)
1939 && fndecl_built_in_p (ddealloc, BUILT_IN_NORMAL))
1941 built_in_function fncode = DECL_FUNCTION_CODE (ddealloc);
1942 if (fncode == BUILT_IN_FREE || fncode == BUILT_IN_REALLOC)
1944 if (alloc_dealloc_kind == alloc_kind_t::builtin)
1945 return true;
1946 realloc_dealloc_kind = alloc_kind_t::builtin;
1948 continue;
1951 if (common_deallocs.add (ddealloc))
1952 return true;
1956 /* Succeed only if ALLOC_DECL and the reallocator DEALLOC_DECL share
1957 a built-in deallocator. */
1958 return (alloc_dealloc_kind == alloc_kind_t::builtin
1959 && realloc_dealloc_kind == alloc_kind_t::builtin);
1962 /* Return true if DEALLOC_DECL is a function suitable to deallocate
1963 objects allocated by the ALLOC call. */
1965 static bool
1966 matching_alloc_calls_p (gimple *alloc, tree dealloc_decl)
1968 tree alloc_decl = gimple_call_fndecl (alloc);
1969 if (!alloc_decl)
1970 return true;
1972 return matching_alloc_calls_p (alloc_decl, dealloc_decl);
1975 /* Diagnose a call EXP to deallocate a pointer referenced by AREF if it
1976 includes a nonzero offset. Such a pointer cannot refer to the beginning
1977 of an allocated object. A negative offset may refer to it only if
1978 the target pointer is unknown. */
1980 static bool
1981 warn_dealloc_offset (location_t loc, gimple *call, const access_ref &aref)
1983 if (aref.deref || aref.offrng[0] <= 0 || aref.offrng[1] <= 0)
1984 return false;
1986 tree dealloc_decl = gimple_call_fndecl (call);
1987 if (!dealloc_decl)
1988 return false;
1990 if (DECL_IS_OPERATOR_DELETE_P (dealloc_decl)
1991 && !DECL_IS_REPLACEABLE_OPERATOR (dealloc_decl))
1993 /* A call to a user-defined operator delete with a pointer plus offset
1994 may be valid if it's returned from an unknown function (i.e., one
1995 that's not operator new). */
1996 if (TREE_CODE (aref.ref) == SSA_NAME)
1998 gimple *def_stmt = SSA_NAME_DEF_STMT (aref.ref);
1999 if (is_gimple_call (def_stmt))
2001 tree alloc_decl = gimple_call_fndecl (def_stmt);
2002 if (!alloc_decl || !DECL_IS_OPERATOR_NEW_P (alloc_decl))
2003 return false;
2008 char offstr[80];
2009 offstr[0] = '\0';
2010 if (wi::fits_shwi_p (aref.offrng[0]))
2012 if (aref.offrng[0] == aref.offrng[1]
2013 || !wi::fits_shwi_p (aref.offrng[1]))
2014 sprintf (offstr, " %lli",
2015 (long long)aref.offrng[0].to_shwi ());
2016 else
2017 sprintf (offstr, " [%lli, %lli]",
2018 (long long)aref.offrng[0].to_shwi (),
2019 (long long)aref.offrng[1].to_shwi ());
2022 if (!warning_at (loc, OPT_Wfree_nonheap_object,
2023 "%qD called on pointer %qE with nonzero offset%s",
2024 dealloc_decl, aref.ref, offstr))
2025 return false;
2027 if (DECL_P (aref.ref))
2028 inform (get_location (aref.ref), "declared here");
2029 else if (TREE_CODE (aref.ref) == SSA_NAME)
2031 gimple *def_stmt = SSA_NAME_DEF_STMT (aref.ref);
2032 if (is_gimple_call (def_stmt))
2034 location_t def_loc = get_location (def_stmt);
2035 tree alloc_decl = gimple_call_fndecl (def_stmt);
2036 if (alloc_decl)
2037 inform (def_loc,
2038 "returned from %qD", alloc_decl);
2039 else if (tree alloc_fntype = gimple_call_fntype (def_stmt))
2040 inform (def_loc,
2041 "returned from %qT", alloc_fntype);
2042 else
2043 inform (def_loc, "obtained here");
2047 return true;
2050 namespace {
2052 const pass_data pass_data_waccess = {
2053 GIMPLE_PASS,
2054 "waccess",
2055 OPTGROUP_NONE,
2056 TV_WARN_ACCESS, /* timer variable */
2057 PROP_cfg, /* properties_required */
2058 0, /* properties_provided */
2059 0, /* properties_destroyed */
2060 0, /* properties_start */
2061 0, /* properties_finish */
2064 /* Pass to detect invalid accesses. */
2065 class pass_waccess : public gimple_opt_pass
2067 public:
2068 pass_waccess (gcc::context *);
2070 ~pass_waccess ();
2072 opt_pass *clone ();
2074 virtual bool gate (function *);
2076 void set_pass_param (unsigned, bool);
2078 virtual unsigned int execute (function *);
2080 private:
2081 /* Not copyable or assignable. */
2082 pass_waccess (pass_waccess &) = delete;
2083 void operator= (pass_waccess &) = delete;
2085 /* Check a call to an atomic built-in function. */
2086 bool check_atomic_builtin (gcall *);
2088 /* Check a call to a built-in function. */
2089 bool check_builtin (gcall *);
2091 /* Check a call to an ordinary function for invalid accesses. */
2092 bool check_call_access (gcall *);
2094 /* Check a non-call statement. */
2095 void check_stmt (gimple *);
2097 /* Check statements in a basic block. */
2098 void check_block (basic_block);
2100 /* Check a call to a function. */
2101 void check_call (gcall *);
2103 /* Check a call to the named built-in function. */
2104 void check_alloca (gcall *);
2105 void check_alloc_size_call (gcall *);
2106 void check_strcat (gcall *);
2107 void check_strncat (gcall *);
2108 void check_stxcpy (gcall *);
2109 void check_stxncpy (gcall *);
2110 void check_strncmp (gcall *);
2111 void check_memop_access (gimple *, tree, tree, tree);
2112 void check_read_access (gimple *, tree, tree = NULL_TREE, int = 1);
2114 void maybe_check_dealloc_call (gcall *);
2115 void maybe_check_access_sizes (rdwr_map *, tree, tree, gimple *);
2116 bool maybe_warn_memmodel (gimple *, tree, tree, const unsigned char *);
2117 void check_atomic_memmodel (gimple *, tree, tree, const unsigned char *);
2119 /* Check for uses of indeterminate pointers. */
2120 void check_pointer_uses (gimple *, tree, tree = NULL_TREE, bool = false);
2122 /* Return the argument that a call returns. */
2123 tree gimple_call_return_arg (gcall *);
2124 tree gimple_call_return_arg_ref (gcall *);
2126 /* Check a call for uses of a dangling pointer arguments. */
2127 void check_call_dangling (gcall *);
2129 /* Check uses of a dangling pointer or those derived from it. */
2130 void check_dangling_uses (tree, tree, bool = false, bool = false);
2131 void check_dangling_uses ();
2132 void check_dangling_stores ();
2133 void check_dangling_stores (basic_block, hash_set<tree> &, auto_bitmap &);
2135 void warn_invalid_pointer (tree, gimple *, gimple *, tree, bool, bool = false);
2137 /* Return true if use follows an invalidating statement. */
2138 bool use_after_inval_p (gimple *, gimple *, bool = false);
2140 /* A pointer_query object to store information about pointers and
2141 their targets in. */
2142 pointer_query m_ptr_qry;
2143 /* Mapping from DECLs and their clobber statements in the function. */
2144 hash_map<tree, gimple *> m_clobbers;
2145 /* A bit is set for each basic block whose statements have been assigned
2146 valid UIDs. */
2147 bitmap m_bb_uids_set;
2148 /* The current function. */
2149 function *m_func;
2150 /* True to run checks for uses of dangling pointers. */
2151 bool m_check_dangling_p;
2152 /* True to run checks early on in the optimization pipeline. */
2153 bool m_early_checks_p;
2156 /* Construct the pass. */
2158 pass_waccess::pass_waccess (gcc::context *ctxt)
2159 : gimple_opt_pass (pass_data_waccess, ctxt),
2160 m_ptr_qry (NULL),
2161 m_clobbers (),
2162 m_bb_uids_set (),
2163 m_func (),
2164 m_check_dangling_p (),
2165 m_early_checks_p ()
2169 /* Return a copy of the pass with RUN_NUMBER one greater than THIS. */
2171 opt_pass*
2172 pass_waccess::clone ()
2174 return new pass_waccess (m_ctxt);
2177 /* Release pointer_query cache. */
2179 pass_waccess::~pass_waccess ()
2181 m_ptr_qry.flush_cache ();
2184 void
2185 pass_waccess::set_pass_param (unsigned int n, bool early)
2187 gcc_assert (n == 0);
2189 m_early_checks_p = early;
2192 /* Return true when any checks performed by the pass are enabled. */
2194 bool
2195 pass_waccess::gate (function *)
2197 return (warn_free_nonheap_object
2198 || warn_mismatched_alloc
2199 || warn_mismatched_new_delete);
2202 /* Initialize ALLOC_OBJECT_SIZE_LIMIT based on the -Walloc-size-larger-than=
2203 setting if the option is specified, or to the maximum object size if it
2204 is not. Return the initialized value. */
2206 static tree
2207 alloc_max_size (void)
2209 HOST_WIDE_INT limit = warn_alloc_size_limit;
2210 if (limit == HOST_WIDE_INT_MAX)
2211 limit = tree_to_shwi (TYPE_MAX_VALUE (ptrdiff_type_node));
2213 return build_int_cst (size_type_node, limit);
2216 /* Diagnose a call EXP to function FN decorated with attribute alloc_size
2217 whose argument numbers given by IDX with values given by ARGS exceed
2218 the maximum object size or cause an unsigned overflow (wrapping) when
2219 multiplied. FN is null when EXP is a call via a function pointer.
2220 When ARGS[0] is null the function does nothing. ARGS[1] may be null
2221 for functions like malloc, and non-null for those like calloc that
2222 are decorated with a two-argument attribute alloc_size. */
2224 void
2225 maybe_warn_alloc_args_overflow (gimple *stmt, const tree args[2],
2226 const int idx[2])
2228 /* The range each of the (up to) two arguments is known to be in. */
2229 tree argrange[2][2] = { { NULL_TREE, NULL_TREE }, { NULL_TREE, NULL_TREE } };
2231 /* Maximum object size set by -Walloc-size-larger-than= or SIZE_MAX / 2. */
2232 tree maxobjsize = alloc_max_size ();
2234 location_t loc = get_location (stmt);
2236 tree fn = gimple_call_fndecl (stmt);
2237 tree fntype = fn ? TREE_TYPE (fn) : gimple_call_fntype (stmt);
2238 bool warned = false;
2240 /* Validate each argument individually. */
2241 for (unsigned i = 0; i != 2 && args[i]; ++i)
2243 if (TREE_CODE (args[i]) == INTEGER_CST)
2245 argrange[i][0] = args[i];
2246 argrange[i][1] = args[i];
2248 if (tree_int_cst_lt (args[i], integer_zero_node))
2250 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2251 "argument %i value %qE is negative",
2252 idx[i] + 1, args[i]);
2254 else if (integer_zerop (args[i]))
2256 /* Avoid issuing -Walloc-zero for allocation functions other
2257 than __builtin_alloca that are declared with attribute
2258 returns_nonnull because there's no portability risk. This
2259 avoids warning for such calls to libiberty's xmalloc and
2260 friends.
2261 Also avoid issuing the warning for calls to function named
2262 "alloca". */
2263 if (fn && fndecl_built_in_p (fn, BUILT_IN_ALLOCA)
2264 ? IDENTIFIER_LENGTH (DECL_NAME (fn)) != 6
2265 : !lookup_attribute ("returns_nonnull",
2266 TYPE_ATTRIBUTES (fntype)))
2267 warned = warning_at (loc, OPT_Walloc_zero,
2268 "argument %i value is zero",
2269 idx[i] + 1);
2271 else if (tree_int_cst_lt (maxobjsize, args[i]))
2273 /* G++ emits calls to ::operator new[](SIZE_MAX) in C++98
2274 mode and with -fno-exceptions as a way to indicate array
2275 size overflow. There's no good way to detect C++98 here
2276 so avoid diagnosing these calls for all C++ modes. */
2277 if (i == 0
2278 && fn
2279 && !args[1]
2280 && lang_GNU_CXX ()
2281 && DECL_IS_OPERATOR_NEW_P (fn)
2282 && integer_all_onesp (args[i]))
2283 continue;
2285 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2286 "argument %i value %qE exceeds "
2287 "maximum object size %E",
2288 idx[i] + 1, args[i], maxobjsize);
2291 else if (TREE_CODE (args[i]) == SSA_NAME
2292 && get_size_range (args[i], argrange[i]))
2294 /* Verify that the argument's range is not negative (including
2295 upper bound of zero). */
2296 if (tree_int_cst_lt (argrange[i][0], integer_zero_node)
2297 && tree_int_cst_le (argrange[i][1], integer_zero_node))
2299 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2300 "argument %i range [%E, %E] is negative",
2301 idx[i] + 1,
2302 argrange[i][0], argrange[i][1]);
2304 else if (tree_int_cst_lt (maxobjsize, argrange[i][0]))
2306 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2307 "argument %i range [%E, %E] exceeds "
2308 "maximum object size %E",
2309 idx[i] + 1,
2310 argrange[i][0], argrange[i][1],
2311 maxobjsize);
2316 if (!argrange[0][0])
2317 return;
2319 /* For a two-argument alloc_size, validate the product of the two
2320 arguments if both of their values or ranges are known. */
2321 if (!warned && tree_fits_uhwi_p (argrange[0][0])
2322 && argrange[1][0] && tree_fits_uhwi_p (argrange[1][0])
2323 && !integer_onep (argrange[0][0])
2324 && !integer_onep (argrange[1][0]))
2326 /* Check for overflow in the product of a function decorated with
2327 attribute alloc_size (X, Y). */
2328 unsigned szprec = TYPE_PRECISION (size_type_node);
2329 wide_int x = wi::to_wide (argrange[0][0], szprec);
2330 wide_int y = wi::to_wide (argrange[1][0], szprec);
2332 wi::overflow_type vflow;
2333 wide_int prod = wi::umul (x, y, &vflow);
2335 if (vflow)
2336 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2337 "product %<%E * %E%> of arguments %i and %i "
2338 "exceeds %<SIZE_MAX%>",
2339 argrange[0][0], argrange[1][0],
2340 idx[0] + 1, idx[1] + 1);
2341 else if (wi::ltu_p (wi::to_wide (maxobjsize, szprec), prod))
2342 warned = warning_at (loc, OPT_Walloc_size_larger_than_,
2343 "product %<%E * %E%> of arguments %i and %i "
2344 "exceeds maximum object size %E",
2345 argrange[0][0], argrange[1][0],
2346 idx[0] + 1, idx[1] + 1,
2347 maxobjsize);
2349 if (warned)
2351 /* Print the full range of each of the two arguments to make
2352 it clear when it is, in fact, in a range and not constant. */
2353 if (argrange[0][0] != argrange [0][1])
2354 inform (loc, "argument %i in the range [%E, %E]",
2355 idx[0] + 1, argrange[0][0], argrange[0][1]);
2356 if (argrange[1][0] != argrange [1][1])
2357 inform (loc, "argument %i in the range [%E, %E]",
2358 idx[1] + 1, argrange[1][0], argrange[1][1]);
2362 if (warned && fn)
2364 location_t fnloc = DECL_SOURCE_LOCATION (fn);
2366 if (DECL_IS_UNDECLARED_BUILTIN (fn))
2367 inform (loc,
2368 "in a call to built-in allocation function %qD", fn);
2369 else
2370 inform (fnloc,
2371 "in a call to allocation function %qD declared here", fn);
2375 /* Check a call to an alloca function for an excessive size. */
2377 void
2378 pass_waccess::check_alloca (gcall *stmt)
2380 if (m_early_checks_p)
2381 return;
2383 if ((warn_vla_limit >= HOST_WIDE_INT_MAX
2384 && warn_alloc_size_limit < warn_vla_limit)
2385 || (warn_alloca_limit >= HOST_WIDE_INT_MAX
2386 && warn_alloc_size_limit < warn_alloca_limit))
2388 /* -Walloca-larger-than and -Wvla-larger-than settings of less
2389 than HWI_MAX override the more general -Walloc-size-larger-than
2390 so unless either of the former options is smaller than the last
2391 one (which would imply that the call was already checked), check
2392 the alloca arguments for overflow. */
2393 const tree alloc_args[] = { call_arg (stmt, 0), NULL_TREE };
2394 const int idx[] = { 0, -1 };
2395 maybe_warn_alloc_args_overflow (stmt, alloc_args, idx);
2399 /* Check a call to an allocation function for an excessive size. */
2401 void
2402 pass_waccess::check_alloc_size_call (gcall *stmt)
2404 if (m_early_checks_p)
2405 return;
2407 if (gimple_call_num_args (stmt) < 1)
2408 /* Avoid invalid calls to functions without a prototype. */
2409 return;
2411 tree fndecl = gimple_call_fndecl (stmt);
2412 if (fndecl && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
2414 /* Alloca is handled separately. */
2415 switch (DECL_FUNCTION_CODE (fndecl))
2417 case BUILT_IN_ALLOCA:
2418 case BUILT_IN_ALLOCA_WITH_ALIGN:
2419 case BUILT_IN_ALLOCA_WITH_ALIGN_AND_MAX:
2420 return;
2421 default:
2422 break;
2426 tree fntype = gimple_call_fntype (stmt);
2427 tree fntypeattrs = TYPE_ATTRIBUTES (fntype);
2429 tree alloc_size = lookup_attribute ("alloc_size", fntypeattrs);
2430 if (!alloc_size)
2431 return;
2433 /* Extract attribute alloc_size from the type of the called expression
2434 (which could be a function or a function pointer) and if set, store
2435 the indices of the corresponding arguments in ALLOC_IDX, and then
2436 the actual argument(s) at those indices in ALLOC_ARGS. */
2437 int idx[2] = { -1, -1 };
2438 tree alloc_args[] = { NULL_TREE, NULL_TREE };
2439 unsigned nargs = gimple_call_num_args (stmt);
2441 tree args = TREE_VALUE (alloc_size);
2442 idx[0] = TREE_INT_CST_LOW (TREE_VALUE (args)) - 1;
2443 /* Avoid invalid calls to functions without a prototype. */
2444 if ((unsigned) idx[0] >= nargs)
2445 return;
2446 alloc_args[0] = call_arg (stmt, idx[0]);
2447 if (TREE_CHAIN (args))
2449 idx[1] = TREE_INT_CST_LOW (TREE_VALUE (TREE_CHAIN (args))) - 1;
2450 if ((unsigned) idx[1] >= nargs)
2451 return;
2452 alloc_args[1] = call_arg (stmt, idx[1]);
2455 maybe_warn_alloc_args_overflow (stmt, alloc_args, idx);
2458 /* Check a call STMT to strcat() for overflow and warn if it does. */
2460 void
2461 pass_waccess::check_strcat (gcall *stmt)
2463 if (m_early_checks_p)
2464 return;
2466 if (!warn_stringop_overflow && !warn_stringop_overread)
2467 return;
2469 tree dest = call_arg (stmt, 0);
2470 tree src = call_arg (stmt, 1);
2472 /* There is no way here to determine the length of the string in
2473 the destination to which the SRC string is being appended so
2474 just diagnose cases when the source string is longer than
2475 the destination object. */
2476 access_data data (m_ptr_qry.rvals, stmt, access_read_write, NULL_TREE,
2477 true, NULL_TREE, true);
2478 const int ost = warn_stringop_overflow ? warn_stringop_overflow - 1 : 1;
2479 compute_objsize (src, stmt, ost, &data.src, &m_ptr_qry);
2480 tree destsize = compute_objsize (dest, stmt, ost, &data.dst, &m_ptr_qry);
2482 check_access (stmt, /*dstwrite=*/NULL_TREE, /*maxread=*/NULL_TREE,
2483 src, destsize, data.mode, &data, m_ptr_qry.rvals);
2486 /* Check a call STMT to strcat() for overflow and warn if it does. */
2488 void
2489 pass_waccess::check_strncat (gcall *stmt)
2491 if (m_early_checks_p)
2492 return;
2494 if (!warn_stringop_overflow && !warn_stringop_overread)
2495 return;
2497 tree dest = call_arg (stmt, 0);
2498 tree src = call_arg (stmt, 1);
2499 /* The upper bound on the number of bytes to write. */
2500 tree maxread = call_arg (stmt, 2);
2502 /* Detect unterminated source (only). */
2503 if (!check_nul_terminated_array (stmt, src, maxread))
2504 return;
2506 /* The length of the source sequence. */
2507 tree slen = c_strlen (src, 1);
2509 /* Try to determine the range of lengths that the source expression
2510 refers to. Since the lengths are only used for warning and not
2511 for code generation disable strict mode below. */
2512 tree maxlen = slen;
2513 if (!maxlen)
2515 c_strlen_data lendata = { };
2516 get_range_strlen (src, &lendata, /* eltsize = */ 1);
2517 maxlen = lendata.maxbound;
2520 access_data data (m_ptr_qry.rvals, stmt, access_read_write);
2521 /* Try to verify that the destination is big enough for the shortest
2522 string. First try to determine the size of the destination object
2523 into which the source is being copied. */
2524 const int ost = warn_stringop_overflow - 1;
2525 tree destsize = compute_objsize (dest, stmt, ost, &data.dst, &m_ptr_qry);
2527 /* Add one for the terminating nul. */
2528 tree srclen = (maxlen
2529 ? fold_build2 (PLUS_EXPR, size_type_node, maxlen,
2530 size_one_node)
2531 : NULL_TREE);
2533 /* The strncat function copies at most MAXREAD bytes and always appends
2534 the terminating nul so the specified upper bound should never be equal
2535 to (or greater than) the size of the destination. */
2536 if (tree_fits_uhwi_p (maxread) && tree_fits_uhwi_p (destsize)
2537 && tree_int_cst_equal (destsize, maxread))
2539 location_t loc = get_location (stmt);
2540 warning_at (loc, OPT_Wstringop_overflow_,
2541 "%qD specified bound %E equals destination size",
2542 get_callee_fndecl (stmt), maxread);
2544 return;
2547 if (!srclen
2548 || (maxread && tree_fits_uhwi_p (maxread)
2549 && tree_fits_uhwi_p (srclen)
2550 && tree_int_cst_lt (maxread, srclen)))
2551 srclen = maxread;
2553 check_access (stmt, /*dstwrite=*/NULL_TREE, maxread, srclen,
2554 destsize, data.mode, &data, m_ptr_qry.rvals);
2557 /* Check a call STMT to stpcpy() or strcpy() for overflow and warn
2558 if it does. */
2560 void
2561 pass_waccess::check_stxcpy (gcall *stmt)
2563 if (m_early_checks_p)
2564 return;
2566 tree dst = call_arg (stmt, 0);
2567 tree src = call_arg (stmt, 1);
2569 tree size;
2570 bool exact;
2571 if (tree nonstr = unterminated_array (src, &size, &exact))
2573 /* NONSTR refers to the non-nul terminated constant array. */
2574 warn_string_no_nul (get_location (stmt), stmt, NULL, src, nonstr,
2575 size, exact);
2576 return;
2579 if (warn_stringop_overflow)
2581 access_data data (m_ptr_qry.rvals, stmt, access_read_write, NULL_TREE,
2582 true, NULL_TREE, true);
2583 const int ost = warn_stringop_overflow ? warn_stringop_overflow - 1 : 1;
2584 compute_objsize (src, stmt, ost, &data.src, &m_ptr_qry);
2585 tree dstsize = compute_objsize (dst, stmt, ost, &data.dst, &m_ptr_qry);
2586 check_access (stmt, /*dstwrite=*/ NULL_TREE,
2587 /*maxread=*/ NULL_TREE, /*srcstr=*/ src,
2588 dstsize, data.mode, &data, m_ptr_qry.rvals);
2591 /* Check to see if the argument was declared attribute nonstring
2592 and if so, issue a warning since at this point it's not known
2593 to be nul-terminated. */
2594 tree fndecl = get_callee_fndecl (stmt);
2595 maybe_warn_nonstring_arg (fndecl, stmt);
2598 /* Check a call STMT to stpncpy() or strncpy() for overflow and warn
2599 if it does. */
2601 void
2602 pass_waccess::check_stxncpy (gcall *stmt)
2604 if (m_early_checks_p || !warn_stringop_overflow)
2605 return;
2607 tree dst = call_arg (stmt, 0);
2608 tree src = call_arg (stmt, 1);
2609 /* The number of bytes to write (not the maximum). */
2610 tree len = call_arg (stmt, 2);
2612 access_data data (m_ptr_qry.rvals, stmt, access_read_write, len, true, len,
2613 true);
2614 const int ost = warn_stringop_overflow ? warn_stringop_overflow - 1 : 1;
2615 compute_objsize (src, stmt, ost, &data.src, &m_ptr_qry);
2616 tree dstsize = compute_objsize (dst, stmt, ost, &data.dst, &m_ptr_qry);
2618 check_access (stmt, /*dstwrite=*/len, /*maxread=*/len, src, dstsize,
2619 data.mode, &data, m_ptr_qry.rvals);
2622 /* Check a call STMT to stpncpy() or strncpy() for overflow and warn
2623 if it does. */
2625 void
2626 pass_waccess::check_strncmp (gcall *stmt)
2628 if (m_early_checks_p || !warn_stringop_overread)
2629 return;
2631 tree arg1 = call_arg (stmt, 0);
2632 tree arg2 = call_arg (stmt, 1);
2633 tree bound = call_arg (stmt, 2);
2635 /* First check each argument separately, considering the bound. */
2636 if (!check_nul_terminated_array (stmt, arg1, bound)
2637 || !check_nul_terminated_array (stmt, arg2, bound))
2638 return;
2640 /* A strncmp read from each argument is constrained not just by
2641 the bound but also by the length of the shorter string. Specifying
2642 a bound that's larger than the size of either array makes no sense
2643 and is likely a bug. When the length of neither of the two strings
2644 is known but the sizes of both of the arrays they are stored in is,
2645 issue a warning if the bound is larger than the size of
2646 the larger of the two arrays. */
2648 c_strlen_data lendata1{ }, lendata2{ };
2649 tree len1 = c_strlen (arg1, 1, &lendata1);
2650 tree len2 = c_strlen (arg2, 1, &lendata2);
2652 if (len1 && TREE_CODE (len1) != INTEGER_CST)
2653 len1 = NULL_TREE;
2654 if (len2 && TREE_CODE (len2) != INTEGER_CST)
2655 len2 = NULL_TREE;
2657 if (len1 && len2)
2658 /* If the length of both arguments was computed they must both be
2659 nul-terminated and no further checking is necessary regardless
2660 of the bound. */
2661 return;
2663 /* Check to see if the argument was declared with attribute nonstring
2664 and if so, issue a warning since at this point it's not known to be
2665 nul-terminated. */
2666 if (maybe_warn_nonstring_arg (get_callee_fndecl (stmt), stmt))
2667 return;
2669 access_data adata1 (m_ptr_qry.rvals, stmt, access_read_only, NULL_TREE, false,
2670 bound, true);
2671 access_data adata2 (m_ptr_qry.rvals, stmt, access_read_only, NULL_TREE, false,
2672 bound, true);
2674 /* Determine the range of the bound first and bail if it fails; it's
2675 cheaper than computing the size of the objects. */
2676 tree bndrng[2] = { NULL_TREE, NULL_TREE };
2677 get_size_range (m_ptr_qry.rvals, bound, stmt, bndrng, adata1.src_bndrng);
2678 if (!bndrng[0] || integer_zerop (bndrng[0]))
2679 return;
2681 if (len1 && tree_int_cst_lt (len1, bndrng[0]))
2682 bndrng[0] = len1;
2683 if (len2 && tree_int_cst_lt (len2, bndrng[0]))
2684 bndrng[0] = len2;
2686 /* compute_objsize almost never fails (and ultimately should never
2687 fail). Don't bother to handle the rare case when it does. */
2688 if (!compute_objsize (arg1, stmt, 1, &adata1.src, &m_ptr_qry)
2689 || !compute_objsize (arg2, stmt, 1, &adata2.src, &m_ptr_qry))
2690 return;
2692 /* Compute the size of the remaining space in each array after
2693 subtracting any offset into it. */
2694 offset_int rem1 = adata1.src.size_remaining ();
2695 offset_int rem2 = adata2.src.size_remaining ();
2697 /* Cap REM1 and REM2 at the other if the other's argument is known
2698 to be an unterminated array, either because there's no space
2699 left in it after adding its offset or because it's constant and
2700 has no nul. */
2701 if (rem1 == 0 || (rem1 < rem2 && lendata1.decl))
2702 rem2 = rem1;
2703 else if (rem2 == 0 || (rem2 < rem1 && lendata2.decl))
2704 rem1 = rem2;
2706 /* Point PAD at the array to reference in the note if a warning
2707 is issued. */
2708 access_data *pad = len1 ? &adata2 : &adata1;
2709 offset_int maxrem = wi::max (rem1, rem2, UNSIGNED);
2710 if (lendata1.decl || lendata2.decl
2711 || maxrem < wi::to_offset (bndrng[0]))
2713 /* Warn when either argument isn't nul-terminated or the maximum
2714 remaining space in the two arrays is less than the bound. */
2715 tree func = get_callee_fndecl (stmt);
2716 location_t loc = gimple_location (stmt);
2717 maybe_warn_for_bound (OPT_Wstringop_overread, loc, stmt, func,
2718 bndrng, wide_int_to_tree (sizetype, maxrem),
2719 pad);
2723 /* Determine and check the sizes of the source and the destination
2724 of calls to __builtin_{bzero,memcpy,mempcpy,memset} calls. STMT is
2725 the call statement, DEST is the destination argument, SRC is the source
2726 argument or null, and SIZE is the number of bytes being accessed. Use
2727 Object Size type-0 regardless of the OPT_Wstringop_overflow_ setting.
2728 Return true on success (no overflow or invalid sizes), false otherwise. */
2730 void
2731 pass_waccess::check_memop_access (gimple *stmt, tree dest, tree src, tree size)
2733 if (m_early_checks_p)
2734 return;
2736 /* For functions like memset and memcpy that operate on raw memory
2737 try to determine the size of the largest source and destination
2738 object using type-0 Object Size regardless of the object size
2739 type specified by the option. */
2740 access_data data (m_ptr_qry.rvals, stmt, access_read_write);
2741 tree srcsize
2742 = src ? compute_objsize (src, stmt, 0, &data.src, &m_ptr_qry) : NULL_TREE;
2743 tree dstsize = compute_objsize (dest, stmt, 0, &data.dst, &m_ptr_qry);
2745 check_access (stmt, size, /*maxread=*/NULL_TREE, srcsize, dstsize,
2746 data.mode, &data, m_ptr_qry.rvals);
2749 /* A convenience wrapper for check_access to check access by a read-only
2750 function like puts or strcmp. */
2752 void
2753 pass_waccess::check_read_access (gimple *stmt, tree src,
2754 tree bound /* = NULL_TREE */,
2755 int ost /* = 1 */)
2757 if (m_early_checks_p || !warn_stringop_overread)
2758 return;
2760 if (bound && !useless_type_conversion_p (size_type_node, TREE_TYPE (bound)))
2761 bound = fold_convert (size_type_node, bound);
2763 tree fndecl = get_callee_fndecl (stmt);
2764 maybe_warn_nonstring_arg (fndecl, stmt);
2766 access_data data (m_ptr_qry.rvals, stmt, access_read_only, NULL_TREE,
2767 false, bound, true);
2768 compute_objsize (src, stmt, ost, &data.src, &m_ptr_qry);
2769 check_access (stmt, /*dstwrite=*/ NULL_TREE, /*maxread=*/ bound,
2770 /*srcstr=*/ src, /*dstsize=*/ NULL_TREE, data.mode,
2771 &data, m_ptr_qry.rvals);
2774 /* Return true if memory model ORD is constant in the context of STMT and
2775 set *CSTVAL to the constant value. Otherwise return false. Warn for
2776 invalid ORD. */
2778 bool
2779 memmodel_to_uhwi (tree ord, gimple *stmt, unsigned HOST_WIDE_INT *cstval)
2781 unsigned HOST_WIDE_INT val;
2783 if (TREE_CODE (ord) == INTEGER_CST)
2785 if (!tree_fits_uhwi_p (ord))
2786 return false;
2787 val = tree_to_uhwi (ord);
2789 else
2791 /* Use the range query to determine constant values in the absence
2792 of constant propagation (such as at -O0). */
2793 value_range rng;
2794 if (!get_range_query (cfun)->range_of_expr (rng, ord, stmt)
2795 || !rng.constant_p ()
2796 || !rng.singleton_p (&ord))
2797 return false;
2799 wide_int lob = rng.lower_bound ();
2800 if (!wi::fits_uhwi_p (lob))
2801 return false;
2803 val = lob.to_shwi ();
2806 if (targetm.memmodel_check)
2807 /* This might warn for an invalid VAL but return a conservatively
2808 valid result. */
2809 val = targetm.memmodel_check (val);
2810 else if (val & ~MEMMODEL_MASK)
2812 tree fndecl = gimple_call_fndecl (stmt);
2813 location_t loc = gimple_location (stmt);
2814 loc = expansion_point_location_if_in_system_header (loc);
2816 warning_at (loc, OPT_Winvalid_memory_model,
2817 "unknown architecture specifier in memory model "
2818 "%wi for %qD", val, fndecl);
2819 return false;
2822 *cstval = val;
2824 return true;
2827 /* Valid memory model for each set of atomic built-in functions. */
2829 struct memmodel_pair
2831 memmodel modval;
2832 const char* modname;
2834 #define MEMMODEL_PAIR(val, str) \
2835 { MEMMODEL_ ## val, "memory_order_" str }
2838 /* Valid memory models in the order of increasing strength. */
2840 static const memmodel_pair memory_models[] =
2841 { MEMMODEL_PAIR (RELAXED, "relaxed"),
2842 MEMMODEL_PAIR (SEQ_CST, "seq_cst"),
2843 MEMMODEL_PAIR (ACQUIRE, "acquire"),
2844 MEMMODEL_PAIR (CONSUME, "consume"),
2845 MEMMODEL_PAIR (RELEASE, "release"),
2846 MEMMODEL_PAIR (ACQ_REL, "acq_rel")
2849 /* Return the name of the memory model VAL. */
2851 static const char*
2852 memmodel_name (unsigned HOST_WIDE_INT val)
2854 val = memmodel_base (val);
2856 for (unsigned i = 0; i != sizeof memory_models / sizeof *memory_models; ++i)
2858 if (val == memory_models[i].modval)
2859 return memory_models[i].modname;
2861 return NULL;
2864 /* Indices of valid MEMORY_MODELS above for corresponding atomic operations. */
2865 static const unsigned char load_models[] = { 0, 1, 2, 3, UCHAR_MAX };
2866 static const unsigned char store_models[] = { 0, 1, 4, UCHAR_MAX };
2867 static const unsigned char xchg_models[] = { 0, 1, 3, 4, 5, UCHAR_MAX };
2868 static const unsigned char flag_clr_models[] = { 0, 1, 4, UCHAR_MAX };
2869 static const unsigned char all_models[] = { 0, 1, 2, 3, 4, 5, UCHAR_MAX };
2871 /* Check the success memory model argument ORD_SUCS to the call STMT to
2872 an atomic function and warn if it's invalid. If nonnull, also check
2873 the failure memory model ORD_FAIL and warn if it's invalid. Return
2874 true if a warning has been issued. */
2876 bool
2877 pass_waccess::maybe_warn_memmodel (gimple *stmt, tree ord_sucs,
2878 tree ord_fail, const unsigned char *valid)
2880 unsigned HOST_WIDE_INT sucs, fail = 0;
2881 if (!memmodel_to_uhwi (ord_sucs, stmt, &sucs)
2882 || (ord_fail && !memmodel_to_uhwi (ord_fail, stmt, &fail)))
2883 return false;
2885 bool is_valid = false;
2886 if (valid)
2887 for (unsigned i = 0; valid[i] != UCHAR_MAX; ++i)
2889 memmodel model = memory_models[valid[i]].modval;
2890 if (memmodel_base (sucs) == model)
2892 is_valid = true;
2893 break;
2896 else
2897 is_valid = true;
2899 tree fndecl = gimple_call_fndecl (stmt);
2900 location_t loc = gimple_location (stmt);
2901 loc = expansion_point_location_if_in_system_header (loc);
2903 if (!is_valid)
2905 bool warned = false;
2906 if (const char *modname = memmodel_name (sucs))
2907 warned = warning_at (loc, OPT_Winvalid_memory_model,
2908 "invalid memory model %qs for %qD",
2909 modname, fndecl);
2910 else
2911 warned = warning_at (loc, OPT_Winvalid_memory_model,
2912 "invalid memory model %wi for %qD",
2913 sucs, fndecl);
2915 if (!warned)
2916 return false;
2918 /* Print a note with the valid memory models. */
2919 pretty_printer pp;
2920 pp_show_color (&pp) = pp_show_color (global_dc->printer);
2921 for (unsigned i = 0; valid[i] != UCHAR_MAX; ++i)
2923 const char *modname = memory_models[valid[i]].modname;
2924 pp_printf (&pp, "%s%qs", i ? ", " : "", modname);
2927 inform (loc, "valid models are %s", pp_formatted_text (&pp));
2928 return true;
2931 if (!ord_fail)
2932 return false;
2934 if (fail == MEMMODEL_RELEASE || fail == MEMMODEL_ACQ_REL)
2935 if (const char *failname = memmodel_name (fail))
2937 /* If both memory model arguments are valid but their combination
2938 is not, use their names in the warning. */
2939 if (!warning_at (loc, OPT_Winvalid_memory_model,
2940 "invalid failure memory model %qs for %qD",
2941 failname, fndecl))
2942 return false;
2944 inform (loc,
2945 "valid failure models are %qs, %qs, %qs, %qs",
2946 "memory_order_relaxed", "memory_order_seq_cst",
2947 "memory_order_acquire", "memory_order_consume");
2948 return true;
2951 if (memmodel_base (fail) <= memmodel_base (sucs))
2952 return false;
2954 if (const char *sucsname = memmodel_name (sucs))
2955 if (const char *failname = memmodel_name (fail))
2957 /* If both memory model arguments are valid but their combination
2958 is not, use their names in the warning. */
2959 if (!warning_at (loc, OPT_Winvalid_memory_model,
2960 "failure memory model %qs cannot be stronger "
2961 "than success memory model %qs for %qD",
2962 failname, sucsname, fndecl))
2963 return false;
2965 /* Print a note with the valid failure memory models which are
2966 those with a value less than or equal to the success mode. */
2967 char buf[120];
2968 *buf = '\0';
2969 for (unsigned i = 0;
2970 memory_models[i].modval <= memmodel_base (sucs); ++i)
2972 if (*buf)
2973 strcat (buf, ", ");
2975 const char *modname = memory_models[valid[i]].modname;
2976 sprintf (buf + strlen (buf), "'%s'", modname);
2979 inform (loc, "valid models are %s", buf);
2980 return true;
2983 /* If either memory model argument value is invalid use the numerical
2984 value of both in the message. */
2985 return warning_at (loc, OPT_Winvalid_memory_model,
2986 "failure memory model %wi cannot be stronger "
2987 "than success memory model %wi for %qD",
2988 fail, sucs, fndecl);
2991 /* Wrapper for the above. */
2993 void
2994 pass_waccess::check_atomic_memmodel (gimple *stmt, tree ord_sucs,
2995 tree ord_fail, const unsigned char *valid)
2997 if (warning_suppressed_p (stmt, OPT_Winvalid_memory_model))
2998 return;
3000 if (!maybe_warn_memmodel (stmt, ord_sucs, ord_fail, valid))
3001 return;
3003 suppress_warning (stmt, OPT_Winvalid_memory_model);
3006 /* Check a call STMT to an atomic or sync built-in. */
3008 bool
3009 pass_waccess::check_atomic_builtin (gcall *stmt)
3011 tree callee = gimple_call_fndecl (stmt);
3012 if (!callee)
3013 return false;
3015 /* The size in bytes of the access by the function, and the number
3016 of the second argument to check (if any). */
3017 unsigned bytes = 0, arg2 = UINT_MAX;
3018 unsigned sucs_arg = UINT_MAX, fail_arg = UINT_MAX;
3019 /* Points to the array of indices of valid memory models. */
3020 const unsigned char *pvalid_models = NULL;
3022 switch (DECL_FUNCTION_CODE (callee))
3024 #define BUILTIN_ACCESS_SIZE_FNSPEC(N) \
3025 BUILT_IN_SYNC_FETCH_AND_ADD_ ## N: \
3026 case BUILT_IN_SYNC_FETCH_AND_SUB_ ## N: \
3027 case BUILT_IN_SYNC_FETCH_AND_OR_ ## N: \
3028 case BUILT_IN_SYNC_FETCH_AND_AND_ ## N: \
3029 case BUILT_IN_SYNC_FETCH_AND_XOR_ ## N: \
3030 case BUILT_IN_SYNC_FETCH_AND_NAND_ ## N: \
3031 case BUILT_IN_SYNC_ADD_AND_FETCH_ ## N: \
3032 case BUILT_IN_SYNC_SUB_AND_FETCH_ ## N: \
3033 case BUILT_IN_SYNC_OR_AND_FETCH_ ## N: \
3034 case BUILT_IN_SYNC_AND_AND_FETCH_ ## N: \
3035 case BUILT_IN_SYNC_XOR_AND_FETCH_ ## N: \
3036 case BUILT_IN_SYNC_NAND_AND_FETCH_ ## N: \
3037 case BUILT_IN_SYNC_LOCK_TEST_AND_SET_ ## N: \
3038 case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_ ## N: \
3039 case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_ ## N: \
3040 case BUILT_IN_SYNC_LOCK_RELEASE_ ## N: \
3041 bytes = N; \
3042 break; \
3043 case BUILT_IN_ATOMIC_LOAD_ ## N: \
3044 pvalid_models = load_models; \
3045 sucs_arg = 1; \
3046 /* FALLTHROUGH */ \
3047 case BUILT_IN_ATOMIC_STORE_ ## N: \
3048 if (!pvalid_models) \
3049 pvalid_models = store_models; \
3050 /* FALLTHROUGH */ \
3051 case BUILT_IN_ATOMIC_ADD_FETCH_ ## N: \
3052 case BUILT_IN_ATOMIC_SUB_FETCH_ ## N: \
3053 case BUILT_IN_ATOMIC_AND_FETCH_ ## N: \
3054 case BUILT_IN_ATOMIC_NAND_FETCH_ ## N: \
3055 case BUILT_IN_ATOMIC_XOR_FETCH_ ## N: \
3056 case BUILT_IN_ATOMIC_OR_FETCH_ ## N: \
3057 case BUILT_IN_ATOMIC_FETCH_ADD_ ## N: \
3058 case BUILT_IN_ATOMIC_FETCH_SUB_ ## N: \
3059 case BUILT_IN_ATOMIC_FETCH_AND_ ## N: \
3060 case BUILT_IN_ATOMIC_FETCH_NAND_ ## N: \
3061 case BUILT_IN_ATOMIC_FETCH_OR_ ## N: \
3062 case BUILT_IN_ATOMIC_FETCH_XOR_ ## N: \
3063 bytes = N; \
3064 if (sucs_arg == UINT_MAX) \
3065 sucs_arg = 2; \
3066 if (!pvalid_models) \
3067 pvalid_models = all_models; \
3068 break; \
3069 case BUILT_IN_ATOMIC_EXCHANGE_ ## N: \
3070 bytes = N; \
3071 sucs_arg = 3; \
3072 pvalid_models = xchg_models; \
3073 break; \
3074 case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_ ## N: \
3075 bytes = N; \
3076 sucs_arg = 4; \
3077 fail_arg = 5; \
3078 pvalid_models = all_models; \
3079 arg2 = 1
3081 case BUILTIN_ACCESS_SIZE_FNSPEC (1);
3082 break;
3083 case BUILTIN_ACCESS_SIZE_FNSPEC (2);
3084 break;
3085 case BUILTIN_ACCESS_SIZE_FNSPEC (4);
3086 break;
3087 case BUILTIN_ACCESS_SIZE_FNSPEC (8);
3088 break;
3089 case BUILTIN_ACCESS_SIZE_FNSPEC (16);
3090 break;
3092 case BUILT_IN_ATOMIC_CLEAR:
3093 sucs_arg = 1;
3094 pvalid_models = flag_clr_models;
3095 break;
3097 default:
3098 return false;
3101 unsigned nargs = gimple_call_num_args (stmt);
3102 if (sucs_arg < nargs)
3104 tree ord_sucs = gimple_call_arg (stmt, sucs_arg);
3105 tree ord_fail = NULL_TREE;
3106 if (fail_arg < nargs)
3107 ord_fail = gimple_call_arg (stmt, fail_arg);
3108 check_atomic_memmodel (stmt, ord_sucs, ord_fail, pvalid_models);
3111 if (!bytes)
3112 return true;
3114 tree size = build_int_cstu (sizetype, bytes);
3115 tree dst = gimple_call_arg (stmt, 0);
3116 check_memop_access (stmt, dst, NULL_TREE, size);
3118 if (arg2 != UINT_MAX)
3120 tree dst = gimple_call_arg (stmt, arg2);
3121 check_memop_access (stmt, dst, NULL_TREE, size);
3124 return true;
3127 /* Check call STMT to a built-in function for invalid accesses. Return
3128 true if a call has been handled. */
3130 bool
3131 pass_waccess::check_builtin (gcall *stmt)
3133 tree callee = gimple_call_fndecl (stmt);
3134 if (!callee)
3135 return false;
3137 switch (DECL_FUNCTION_CODE (callee))
3139 case BUILT_IN_ALLOCA:
3140 case BUILT_IN_ALLOCA_WITH_ALIGN:
3141 case BUILT_IN_ALLOCA_WITH_ALIGN_AND_MAX:
3142 check_alloca (stmt);
3143 return true;
3145 case BUILT_IN_EXECL:
3146 case BUILT_IN_EXECLE:
3147 case BUILT_IN_EXECLP:
3148 case BUILT_IN_EXECV:
3149 case BUILT_IN_EXECVE:
3150 case BUILT_IN_EXECVP:
3151 check_read_access (stmt, call_arg (stmt, 0));
3152 return true;
3154 case BUILT_IN_FREE:
3155 case BUILT_IN_REALLOC:
3156 if (!m_early_checks_p)
3158 tree arg = call_arg (stmt, 0);
3159 if (TREE_CODE (arg) == SSA_NAME)
3160 check_pointer_uses (stmt, arg);
3162 return true;
3164 case BUILT_IN_GETTEXT:
3165 case BUILT_IN_PUTS:
3166 case BUILT_IN_PUTS_UNLOCKED:
3167 case BUILT_IN_STRDUP:
3168 check_read_access (stmt, call_arg (stmt, 0));
3169 return true;
3171 case BUILT_IN_INDEX:
3172 case BUILT_IN_RINDEX:
3173 case BUILT_IN_STRCHR:
3174 case BUILT_IN_STRRCHR:
3175 case BUILT_IN_STRLEN:
3176 check_read_access (stmt, call_arg (stmt, 0));
3177 return true;
3179 case BUILT_IN_FPUTS:
3180 case BUILT_IN_FPUTS_UNLOCKED:
3181 check_read_access (stmt, call_arg (stmt, 0));
3182 return true;
3184 case BUILT_IN_STRNDUP:
3185 case BUILT_IN_STRNLEN:
3187 tree str = call_arg (stmt, 0);
3188 tree len = call_arg (stmt, 1);
3189 check_read_access (stmt, str, len);
3190 return true;
3193 case BUILT_IN_STRCAT:
3194 check_strcat (stmt);
3195 return true;
3197 case BUILT_IN_STRNCAT:
3198 check_strncat (stmt);
3199 return true;
3201 case BUILT_IN_STPCPY:
3202 case BUILT_IN_STRCPY:
3203 check_stxcpy (stmt);
3204 return true;
3206 case BUILT_IN_STPNCPY:
3207 case BUILT_IN_STRNCPY:
3208 check_stxncpy (stmt);
3209 return true;
3211 case BUILT_IN_STRCASECMP:
3212 case BUILT_IN_STRCMP:
3213 case BUILT_IN_STRPBRK:
3214 case BUILT_IN_STRSPN:
3215 case BUILT_IN_STRCSPN:
3216 case BUILT_IN_STRSTR:
3217 check_read_access (stmt, call_arg (stmt, 0));
3218 check_read_access (stmt, call_arg (stmt, 1));
3219 return true;
3221 case BUILT_IN_STRNCASECMP:
3222 case BUILT_IN_STRNCMP:
3223 check_strncmp (stmt);
3224 return true;
3226 case BUILT_IN_MEMCMP:
3228 tree a1 = call_arg (stmt, 0);
3229 tree a2 = call_arg (stmt, 1);
3230 tree len = call_arg (stmt, 2);
3231 check_read_access (stmt, a1, len, 0);
3232 check_read_access (stmt, a2, len, 0);
3233 return true;
3236 case BUILT_IN_MEMCPY:
3237 case BUILT_IN_MEMPCPY:
3238 case BUILT_IN_MEMMOVE:
3240 tree dst = call_arg (stmt, 0);
3241 tree src = call_arg (stmt, 1);
3242 tree len = call_arg (stmt, 2);
3243 check_memop_access (stmt, dst, src, len);
3244 return true;
3247 case BUILT_IN_MEMCHR:
3249 tree src = call_arg (stmt, 0);
3250 tree len = call_arg (stmt, 2);
3251 check_read_access (stmt, src, len, 0);
3252 return true;
3255 case BUILT_IN_MEMSET:
3257 tree dst = call_arg (stmt, 0);
3258 tree len = call_arg (stmt, 2);
3259 check_memop_access (stmt, dst, NULL_TREE, len);
3260 return true;
3263 default:
3264 if (check_atomic_builtin (stmt))
3265 return true;
3266 break;
3269 return false;
3272 /* Returns the type of the argument ARGNO to function with type FNTYPE
3273 or null when the type cannot be determined or no such argument exists. */
3275 static tree
3276 fntype_argno_type (tree fntype, unsigned argno)
3278 if (!prototype_p (fntype))
3279 return NULL_TREE;
3281 tree argtype;
3282 function_args_iterator it;
3283 FOREACH_FUNCTION_ARGS (fntype, argtype, it)
3284 if (argno-- == 0)
3285 return argtype;
3287 return NULL_TREE;
3290 /* Helper to append the "human readable" attribute access specification
3291 described by ACCESS to the array ATTRSTR with size STRSIZE. Used in
3292 diagnostics. */
3294 static inline void
3295 append_attrname (const std::pair<int, attr_access> &access,
3296 char *attrstr, size_t strsize)
3298 if (access.second.internal_p)
3299 return;
3301 tree str = access.second.to_external_string ();
3302 gcc_assert (strsize >= (size_t) TREE_STRING_LENGTH (str));
3303 strcpy (attrstr, TREE_STRING_POINTER (str));
3306 /* Iterate over attribute access read-only, read-write, and write-only
3307 arguments and diagnose past-the-end accesses and related problems
3308 in the function call EXP. */
3310 void
3311 pass_waccess::maybe_check_access_sizes (rdwr_map *rwm, tree fndecl, tree fntype,
3312 gimple *stmt)
3314 auto_diagnostic_group adg;
3316 /* Set if a warning has been issued for any argument (used to decide
3317 whether to emit an informational note at the end). */
3318 opt_code opt_warned = no_warning;
3320 /* A string describing the attributes that the warnings issued by this
3321 function apply to. Used to print one informational note per function
3322 call, rather than one per warning. That reduces clutter. */
3323 char attrstr[80];
3324 attrstr[0] = 0;
3326 for (rdwr_map::iterator it = rwm->begin (); it != rwm->end (); ++it)
3328 std::pair<int, attr_access> access = *it;
3330 /* Get the function call arguments corresponding to the attribute's
3331 positional arguments. When both arguments have been specified
3332 there will be two entries in *RWM, one for each. They are
3333 cross-referenced by their respective argument numbers in
3334 ACCESS.PTRARG and ACCESS.SIZARG. */
3335 const int ptridx = access.second.ptrarg;
3336 const int sizidx = access.second.sizarg;
3338 gcc_assert (ptridx != -1);
3339 gcc_assert (access.first == ptridx || access.first == sizidx);
3341 /* The pointer is set to null for the entry corresponding to
3342 the size argument. Skip it. It's handled when the entry
3343 corresponding to the pointer argument comes up. */
3344 if (!access.second.ptr)
3345 continue;
3347 tree ptrtype = fntype_argno_type (fntype, ptridx);
3348 if (!ptrtype)
3349 /* A function with a prototype was redeclared without one and
3350 the prototype has been lost. See pr102759. Avoid dealing
3351 with this pathological case. */
3352 return;
3354 tree argtype = TREE_TYPE (ptrtype);
3356 /* The size of the access by the call in elements. */
3357 tree access_nelts;
3358 if (sizidx == -1)
3360 /* If only the pointer attribute operand was specified and
3361 not size, set SIZE to the greater of MINSIZE or size of
3362 one element of the pointed to type to detect smaller
3363 objects (null pointers are diagnosed in this case only
3364 if the pointer is also declared with attribute nonnull. */
3365 if (access.second.minsize
3366 && access.second.minsize != HOST_WIDE_INT_M1U)
3367 access_nelts = build_int_cstu (sizetype, access.second.minsize);
3368 else if (VOID_TYPE_P (argtype) && access.second.mode == access_none)
3369 /* Treat access mode none on a void* argument as expecting
3370 as little as zero bytes. */
3371 access_nelts = size_zero_node;
3372 else
3373 access_nelts = size_one_node;
3375 else
3376 access_nelts = rwm->get (sizidx)->size;
3378 /* Format the value or range to avoid an explosion of messages. */
3379 char sizstr[80];
3380 tree sizrng[2] = { size_zero_node, build_all_ones_cst (sizetype) };
3381 if (get_size_range (m_ptr_qry.rvals, access_nelts, stmt, sizrng, 1))
3383 char *s0 = print_generic_expr_to_str (sizrng[0]);
3384 if (tree_int_cst_equal (sizrng[0], sizrng[1]))
3386 gcc_checking_assert (strlen (s0) < sizeof sizstr);
3387 strcpy (sizstr, s0);
3389 else
3391 char *s1 = print_generic_expr_to_str (sizrng[1]);
3392 gcc_checking_assert (strlen (s0) + strlen (s1)
3393 < sizeof sizstr - 4);
3394 sprintf (sizstr, "[%.37s, %.37s]", s0, s1);
3395 free (s1);
3397 free (s0);
3399 else
3400 *sizstr = '\0';
3402 /* Set if a warning has been issued for the current argument. */
3403 opt_code arg_warned = no_warning;
3404 location_t loc = get_location (stmt);
3405 tree ptr = access.second.ptr;
3406 if (*sizstr
3407 && tree_int_cst_sgn (sizrng[0]) < 0
3408 && tree_int_cst_sgn (sizrng[1]) < 0)
3410 /* Warn about negative sizes. */
3411 if (access.second.internal_p)
3413 const std::string argtypestr
3414 = access.second.array_as_string (ptrtype);
3416 if (warning_at (loc, OPT_Wstringop_overflow_,
3417 "bound argument %i value %s is "
3418 "negative for a variable length array "
3419 "argument %i of type %s",
3420 sizidx + 1, sizstr,
3421 ptridx + 1, argtypestr.c_str ()))
3422 arg_warned = OPT_Wstringop_overflow_;
3424 else if (warning_at (loc, OPT_Wstringop_overflow_,
3425 "argument %i value %s is negative",
3426 sizidx + 1, sizstr))
3427 arg_warned = OPT_Wstringop_overflow_;
3429 if (arg_warned != no_warning)
3431 append_attrname (access, attrstr, sizeof attrstr);
3432 /* Remember a warning has been issued and avoid warning
3433 again below for the same attribute. */
3434 opt_warned = arg_warned;
3435 continue;
3439 /* The size of the access by the call in bytes. */
3440 tree access_size = NULL_TREE;
3441 if (tree_int_cst_sgn (sizrng[0]) >= 0)
3443 if (COMPLETE_TYPE_P (argtype))
3445 /* Multiply ACCESS_SIZE by the size of the type the pointer
3446 argument points to. If it's incomplete the size is used
3447 as is. */
3448 if (tree argsize = TYPE_SIZE_UNIT (argtype))
3449 if (TREE_CODE (argsize) == INTEGER_CST)
3451 const int prec = TYPE_PRECISION (sizetype);
3452 wide_int minsize = wi::to_wide (sizrng[0], prec);
3453 minsize *= wi::to_wide (argsize, prec);
3454 access_size = wide_int_to_tree (sizetype, minsize);
3457 else
3458 access_size = access_nelts;
3461 if (integer_zerop (ptr))
3463 if (sizidx >= 0 && tree_int_cst_sgn (sizrng[0]) > 0)
3465 /* Warn about null pointers with positive sizes. This is
3466 different from also declaring the pointer argument with
3467 attribute nonnull when the function accepts null pointers
3468 only when the corresponding size is zero. */
3469 if (access.second.internal_p)
3471 const std::string argtypestr
3472 = access.second.array_as_string (ptrtype);
3474 if (warning_at (loc, OPT_Wnonnull,
3475 "argument %i of variable length "
3476 "array %s is null but "
3477 "the corresponding bound argument "
3478 "%i value is %s",
3479 ptridx + 1, argtypestr.c_str (),
3480 sizidx + 1, sizstr))
3481 arg_warned = OPT_Wnonnull;
3483 else if (warning_at (loc, OPT_Wnonnull,
3484 "argument %i is null but "
3485 "the corresponding size argument "
3486 "%i value is %s",
3487 ptridx + 1, sizidx + 1, sizstr))
3488 arg_warned = OPT_Wnonnull;
3490 else if (access_size && access.second.static_p)
3492 /* Warn about null pointers for [static N] array arguments
3493 but do not warn for ordinary (i.e., nonstatic) arrays. */
3494 if (warning_at (loc, OPT_Wnonnull,
3495 "argument %i to %<%T[static %E]%> "
3496 "is null where non-null expected",
3497 ptridx + 1, argtype, access_size))
3498 arg_warned = OPT_Wnonnull;
3501 if (arg_warned != no_warning)
3503 append_attrname (access, attrstr, sizeof attrstr);
3504 /* Remember a warning has been issued and avoid warning
3505 again below for the same attribute. */
3506 opt_warned = OPT_Wnonnull;
3507 continue;
3511 access_data data (m_ptr_qry.rvals, stmt, access.second.mode,
3512 NULL_TREE, false, NULL_TREE, false);
3513 access_ref* const pobj = (access.second.mode == access_write_only
3514 ? &data.dst : &data.src);
3515 tree objsize = compute_objsize (ptr, stmt, 1, pobj, &m_ptr_qry);
3517 /* The size of the destination or source object. */
3518 tree dstsize = NULL_TREE, srcsize = NULL_TREE;
3519 if (access.second.mode == access_read_only
3520 || access.second.mode == access_none)
3522 /* For a read-only argument there is no destination. For
3523 no access, set the source as well and differentiate via
3524 the access flag below. */
3525 srcsize = objsize;
3526 if (access.second.mode == access_read_only
3527 || access.second.mode == access_none)
3529 /* For a read-only attribute there is no destination so
3530 clear OBJSIZE. This emits "reading N bytes" kind of
3531 diagnostics instead of the "writing N bytes" kind,
3532 unless MODE is none. */
3533 objsize = NULL_TREE;
3536 else
3537 dstsize = objsize;
3539 /* Clear the no-warning bit in case it was set by check_access
3540 in a prior iteration so that accesses via different arguments
3541 are diagnosed. */
3542 suppress_warning (stmt, OPT_Wstringop_overflow_, false);
3543 access_mode mode = data.mode;
3544 if (mode == access_deferred)
3545 mode = TYPE_READONLY (argtype) ? access_read_only : access_read_write;
3546 check_access (stmt, access_size, /*maxread=*/ NULL_TREE, srcsize,
3547 dstsize, mode, &data, m_ptr_qry.rvals);
3549 if (warning_suppressed_p (stmt, OPT_Wstringop_overflow_))
3550 opt_warned = OPT_Wstringop_overflow_;
3551 if (opt_warned != no_warning)
3553 if (access.second.internal_p)
3555 unsigned HOST_WIDE_INT nelts =
3556 access_nelts ? access.second.minsize : HOST_WIDE_INT_M1U;
3557 tree arrtype = build_printable_array_type (argtype, nelts);
3558 inform (loc, "referencing argument %u of type %qT",
3559 ptridx + 1, arrtype);
3561 else
3562 /* If check_access issued a warning above, append the relevant
3563 attribute to the string. */
3564 append_attrname (access, attrstr, sizeof attrstr);
3568 if (*attrstr)
3570 if (fndecl)
3571 inform (get_location (fndecl),
3572 "in a call to function %qD declared with attribute %qs",
3573 fndecl, attrstr);
3574 else
3575 inform (get_location (stmt),
3576 "in a call with type %qT and attribute %qs",
3577 fntype, attrstr);
3579 else if (opt_warned != no_warning)
3581 if (fndecl)
3582 inform (get_location (fndecl),
3583 "in a call to function %qD", fndecl);
3584 else
3585 inform (get_location (stmt),
3586 "in a call with type %qT", fntype);
3589 /* Set the bit in case if was cleared and not set above. */
3590 if (opt_warned != no_warning)
3591 suppress_warning (stmt, opt_warned);
3594 /* Check call STMT to an ordinary (non-built-in) function for invalid
3595 accesses. Return true if a call has been handled. */
3597 bool
3598 pass_waccess::check_call_access (gcall *stmt)
3600 tree fntype = gimple_call_fntype (stmt);
3601 if (!fntype)
3602 return false;
3604 tree fntypeattrs = TYPE_ATTRIBUTES (fntype);
3605 if (!fntypeattrs)
3606 return false;
3608 /* Map of attribute access specifications for function arguments. */
3609 rdwr_map rdwr_idx;
3610 init_attr_rdwr_indices (&rdwr_idx, fntypeattrs);
3612 unsigned nargs = call_nargs (stmt);
3613 for (unsigned i = 0; i != nargs; ++i)
3615 tree arg = call_arg (stmt, i);
3617 /* Save the actual argument that corresponds to the access attribute
3618 operand for later processing. */
3619 if (attr_access *access = rdwr_idx.get (i))
3621 if (POINTER_TYPE_P (TREE_TYPE (arg)))
3623 access->ptr = arg;
3624 /* A nonnull ACCESS->SIZE contains VLA bounds. */
3626 else
3628 access->size = arg;
3629 gcc_assert (access->ptr == NULL_TREE);
3634 /* Check attribute access arguments. */
3635 tree fndecl = gimple_call_fndecl (stmt);
3636 maybe_check_access_sizes (&rdwr_idx, fndecl, fntype, stmt);
3638 check_alloc_size_call (stmt);
3639 return true;
3642 /* Check arguments in a call STMT for attribute nonstring. */
3644 static void
3645 check_nonstring_args (gcall *stmt)
3647 tree fndecl = gimple_call_fndecl (stmt);
3649 /* Detect passing non-string arguments to functions expecting
3650 nul-terminated strings. */
3651 maybe_warn_nonstring_arg (fndecl, stmt);
3654 /* Issue a warning if a deallocation function such as free, realloc,
3655 or C++ operator delete is called with an argument not returned by
3656 a matching allocation function such as malloc or the corresponding
3657 form of C++ operator new. */
3659 void
3660 pass_waccess::maybe_check_dealloc_call (gcall *call)
3662 tree fndecl = gimple_call_fndecl (call);
3663 if (!fndecl)
3664 return;
3666 unsigned argno = fndecl_dealloc_argno (fndecl);
3667 if ((unsigned) call_nargs (call) <= argno)
3668 return;
3670 tree ptr = gimple_call_arg (call, argno);
3671 if (integer_zerop (ptr))
3672 return;
3674 access_ref aref;
3675 if (!compute_objsize (ptr, call, 0, &aref, &m_ptr_qry))
3676 return;
3678 tree ref = aref.ref;
3679 if (integer_zerop (ref))
3680 return;
3682 tree dealloc_decl = fndecl;
3683 location_t loc = gimple_location (call);
3685 if (DECL_P (ref) || EXPR_P (ref))
3687 /* Diagnose freeing a declared object. */
3688 if (aref.ref_declared ()
3689 && warning_at (loc, OPT_Wfree_nonheap_object,
3690 "%qD called on unallocated object %qD",
3691 dealloc_decl, ref))
3693 inform (get_location (ref), "declared here");
3694 return;
3697 /* Diagnose freeing a pointer that includes a positive offset.
3698 Such a pointer cannot refer to the beginning of an allocated
3699 object. A negative offset may refer to it. */
3700 if (aref.sizrng[0] != aref.sizrng[1]
3701 && warn_dealloc_offset (loc, call, aref))
3702 return;
3704 else if (CONSTANT_CLASS_P (ref))
3706 if (warning_at (loc, OPT_Wfree_nonheap_object,
3707 "%qD called on a pointer to an unallocated "
3708 "object %qE", dealloc_decl, ref))
3710 if (TREE_CODE (ptr) == SSA_NAME)
3712 gimple *def_stmt = SSA_NAME_DEF_STMT (ptr);
3713 if (is_gimple_assign (def_stmt))
3715 location_t loc = gimple_location (def_stmt);
3716 inform (loc, "assigned here");
3719 return;
3722 else if (TREE_CODE (ref) == SSA_NAME)
3724 /* Also warn if the pointer argument refers to the result
3725 of an allocation call like alloca or VLA. */
3726 gimple *def_stmt = SSA_NAME_DEF_STMT (ref);
3727 if (!def_stmt)
3728 return;
3730 if (is_gimple_call (def_stmt))
3732 bool warned = false;
3733 if (gimple_call_alloc_p (def_stmt))
3735 if (matching_alloc_calls_p (def_stmt, dealloc_decl))
3737 if (warn_dealloc_offset (loc, call, aref))
3738 return;
3740 else
3742 tree alloc_decl = gimple_call_fndecl (def_stmt);
3743 const opt_code opt =
3744 (DECL_IS_OPERATOR_NEW_P (alloc_decl)
3745 || DECL_IS_OPERATOR_DELETE_P (dealloc_decl)
3746 ? OPT_Wmismatched_new_delete
3747 : OPT_Wmismatched_dealloc);
3748 warned = warning_at (loc, opt,
3749 "%qD called on pointer returned "
3750 "from a mismatched allocation "
3751 "function", dealloc_decl);
3754 else if (gimple_call_builtin_p (def_stmt, BUILT_IN_ALLOCA)
3755 || gimple_call_builtin_p (def_stmt,
3756 BUILT_IN_ALLOCA_WITH_ALIGN))
3757 warned = warning_at (loc, OPT_Wfree_nonheap_object,
3758 "%qD called on pointer to "
3759 "an unallocated object",
3760 dealloc_decl);
3761 else if (warn_dealloc_offset (loc, call, aref))
3762 return;
3764 if (warned)
3766 tree fndecl = gimple_call_fndecl (def_stmt);
3767 inform (gimple_location (def_stmt),
3768 "returned from %qD", fndecl);
3769 return;
3772 else if (gimple_nop_p (def_stmt))
3774 ref = SSA_NAME_VAR (ref);
3775 /* Diagnose freeing a pointer that includes a positive offset. */
3776 if (TREE_CODE (ref) == PARM_DECL
3777 && !aref.deref
3778 && aref.sizrng[0] != aref.sizrng[1]
3779 && aref.offrng[0] > 0 && aref.offrng[1] > 0
3780 && warn_dealloc_offset (loc, call, aref))
3781 return;
3786 /* Return true if either USE_STMT's basic block (that of a pointer's use)
3787 is dominated by INVAL_STMT's (that of a pointer's invalidating statement,
3788 which is either a clobber or a deallocation call), or if they're in
3789 the same block, USE_STMT follows INVAL_STMT. */
3791 bool
3792 pass_waccess::use_after_inval_p (gimple *inval_stmt, gimple *use_stmt,
3793 bool last_block /* = false */)
3795 tree clobvar =
3796 gimple_clobber_p (inval_stmt) ? gimple_assign_lhs (inval_stmt) : NULL_TREE;
3798 basic_block inval_bb = gimple_bb (inval_stmt);
3799 basic_block use_bb = gimple_bb (use_stmt);
3801 if (!inval_bb || !use_bb)
3802 return false;
3804 if (inval_bb != use_bb)
3806 if (dominated_by_p (CDI_DOMINATORS, use_bb, inval_bb))
3807 return true;
3809 if (!clobvar || !last_block)
3810 return false;
3812 /* Proceed only when looking for uses of dangling pointers. */
3813 auto gsi = gsi_for_stmt (use_stmt);
3815 /* A use statement in the last basic block in a function or one that
3816 falls through to it is after any other prior clobber of the used
3817 variable unless it's followed by a clobber of the same variable. */
3818 basic_block bb = use_bb;
3819 while (bb != inval_bb
3820 && single_succ_p (bb)
3821 && !(single_succ_edge (bb)->flags
3822 & (EDGE_EH | EDGE_ABNORMAL | EDGE_DFS_BACK)))
3824 for (; !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
3826 gimple *stmt = gsi_stmt (gsi);
3827 if (gimple_clobber_p (stmt))
3829 if (clobvar == gimple_assign_lhs (stmt))
3830 /* The use is followed by a clobber. */
3831 return false;
3835 bb = single_succ (bb);
3836 gsi = gsi_start_bb (bb);
3839 /* The use is one of a dangling pointer if a clobber of the variable
3840 [the pointer points to] has not been found before the function exit
3841 point. */
3842 return bb == EXIT_BLOCK_PTR_FOR_FN (cfun);
3845 if (bitmap_set_bit (m_bb_uids_set, inval_bb->index))
3846 /* The first time this basic block is visited assign increasing ids
3847 to consecutive statements in it. Use the ids to determine which
3848 precedes which. This avoids the linear traversal on subsequent
3849 visits to the same block. */
3850 for (auto si = gsi_start_bb (inval_bb); !gsi_end_p (si);
3851 gsi_next_nondebug (&si))
3853 gimple *stmt = gsi_stmt (si);
3854 unsigned uid = inc_gimple_stmt_max_uid (m_func);
3855 gimple_set_uid (stmt, uid);
3858 return gimple_uid (inval_stmt) < gimple_uid (use_stmt);
3861 /* Issue a warning for the USE_STMT of pointer or reference REF rendered
3862 invalid by INVAL_STMT. REF may be null when it's been optimized away.
3863 When nonnull, INVAL_STMT is the deallocation function that rendered
3864 the pointer or reference dangling. Otherwise, VAR is the auto variable
3865 (including an unnamed temporary such as a compound literal) whose
3866 lifetime's rended it dangling. MAYBE is true to issue the "maybe"
3867 kind of warning. EQUALITY is true when the pointer is used in
3868 an equality expression. */
3870 void
3871 pass_waccess::warn_invalid_pointer (tree ref, gimple *use_stmt,
3872 gimple *inval_stmt, tree var,
3873 bool maybe, bool equality /* = false */)
3875 /* Avoid printing the unhelpful "<unknown>" in the diagnostics. */
3876 if (ref && TREE_CODE (ref) == SSA_NAME)
3878 tree var = SSA_NAME_VAR (ref);
3879 if (!var)
3880 ref = NULL_TREE;
3881 /* Don't warn for cases like when a cdtor returns 'this' on ARM. */
3882 else if (warning_suppressed_p (var, OPT_Wuse_after_free))
3883 return;
3884 else if (DECL_ARTIFICIAL (var))
3885 ref = NULL_TREE;
3888 location_t use_loc = gimple_location (use_stmt);
3889 if (use_loc == UNKNOWN_LOCATION)
3891 use_loc = m_func->function_end_locus;
3892 if (!ref)
3893 /* Avoid issuing a warning with no context other than
3894 the function. That would make it difficult to debug
3895 in any but very simple cases. */
3896 return;
3899 if (is_gimple_call (inval_stmt))
3901 if ((equality && warn_use_after_free < 3)
3902 || (maybe && warn_use_after_free < 2)
3903 || warning_suppressed_p (use_stmt, OPT_Wuse_after_free))
3904 return;
3906 const tree inval_decl = gimple_call_fndecl (inval_stmt);
3908 if ((ref && warning_at (use_loc, OPT_Wuse_after_free,
3909 (maybe
3910 ? G_("pointer %qE may be used after %qD")
3911 : G_("pointer %qE used after %qD")),
3912 ref, inval_decl))
3913 || (!ref && warning_at (use_loc, OPT_Wuse_after_free,
3914 (maybe
3915 ? G_("pointer may be used after %qD")
3916 : G_("pointer used after %qD")),
3917 inval_decl)))
3919 location_t loc = gimple_location (inval_stmt);
3920 inform (loc, "call to %qD here", inval_decl);
3921 suppress_warning (use_stmt, OPT_Wuse_after_free);
3923 return;
3926 if (equality
3927 || (maybe && warn_dangling_pointer < 2)
3928 || warning_suppressed_p (use_stmt, OPT_Wdangling_pointer_))
3929 return;
3931 if (DECL_NAME (var))
3933 if ((ref
3934 && warning_at (use_loc, OPT_Wdangling_pointer_,
3935 (maybe
3936 ? G_("dangling pointer %qE to %qD may be used")
3937 : G_("using dangling pointer %qE to %qD")),
3938 ref, var))
3939 || (!ref
3940 && warning_at (use_loc, OPT_Wdangling_pointer_,
3941 (maybe
3942 ? G_("dangling pointer to %qD may be used")
3943 : G_("using a dangling pointer to %qD")),
3944 var)))
3945 inform (DECL_SOURCE_LOCATION (var),
3946 "%qD declared here", var);
3947 suppress_warning (use_stmt, OPT_Wdangling_pointer_);
3948 return;
3951 if ((ref
3952 && warning_at (use_loc, OPT_Wdangling_pointer_,
3953 (maybe
3954 ? G_("dangling pointer %qE to an unnamed temporary "
3955 "may be used")
3956 : G_("using dangling pointer %qE to an unnamed "
3957 "temporary")),
3958 ref))
3959 || (!ref
3960 && warning_at (use_loc, OPT_Wdangling_pointer_,
3961 (maybe
3962 ? G_("dangling pointer to an unnamed temporary "
3963 "may be used")
3964 : G_("using a dangling pointer to an unnamed "
3965 "temporary")))))
3967 inform (DECL_SOURCE_LOCATION (var),
3968 "unnamed temporary defined here");
3969 suppress_warning (use_stmt, OPT_Wdangling_pointer_);
3973 /* If STMT is a call to either the standard realloc or to a user-defined
3974 reallocation function returns its LHS and set *PTR to the reallocated
3975 pointer. Otherwise return null. */
3977 static tree
3978 get_realloc_lhs (gimple *stmt, tree *ptr)
3980 if (gimple_call_builtin_p (stmt, BUILT_IN_REALLOC))
3982 *ptr = gimple_call_arg (stmt, 0);
3983 return gimple_call_lhs (stmt);
3986 gcall *call = dyn_cast<gcall *>(stmt);
3987 if (!call)
3988 return NULL_TREE;
3990 tree fnattr = NULL_TREE;
3991 tree fndecl = gimple_call_fndecl (call);
3992 if (fndecl)
3993 fnattr = DECL_ATTRIBUTES (fndecl);
3994 else
3996 tree fntype = gimple_call_fntype (stmt);
3997 if (!fntype)
3998 return NULL_TREE;
3999 fnattr = TYPE_ATTRIBUTES (fntype);
4002 if (!fnattr)
4003 return NULL_TREE;
4005 for (tree ats = fnattr; (ats = lookup_attribute ("*dealloc", ats));
4006 ats = TREE_CHAIN (ats))
4008 tree args = TREE_VALUE (ats);
4009 if (!args)
4010 continue;
4012 tree alloc = TREE_VALUE (args);
4013 if (!alloc)
4014 continue;
4016 if (alloc == DECL_NAME (fndecl))
4018 unsigned argno = 0;
4019 if (tree index = TREE_CHAIN (args))
4020 argno = TREE_INT_CST_LOW (TREE_VALUE (index)) - 1;
4021 *ptr = gimple_call_arg (stmt, argno);
4022 return gimple_call_lhs (stmt);
4026 return NULL_TREE;
4029 /* Warn if STMT is a call to a deallocation function that's not a match
4030 for the REALLOC_STMT call. Return true if warned. */
4032 static bool
4033 maybe_warn_mismatched_realloc (tree ptr, gimple *realloc_stmt, gimple *stmt)
4035 if (!is_gimple_call (stmt))
4036 return false;
4038 tree fndecl = gimple_call_fndecl (stmt);
4039 if (!fndecl)
4040 return false;
4042 unsigned argno = fndecl_dealloc_argno (fndecl);
4043 if (call_nargs (stmt) <= argno)
4044 return false;
4046 if (matching_alloc_calls_p (realloc_stmt, fndecl))
4047 return false;
4049 /* Avoid printing the unhelpful "<unknown>" in the diagnostics. */
4050 if (ptr && TREE_CODE (ptr) == SSA_NAME
4051 && (!SSA_NAME_VAR (ptr) || DECL_ARTIFICIAL (SSA_NAME_VAR (ptr))))
4052 ptr = NULL_TREE;
4054 location_t loc = gimple_location (stmt);
4055 tree realloc_decl = gimple_call_fndecl (realloc_stmt);
4056 tree dealloc_decl = gimple_call_fndecl (stmt);
4057 if (ptr && !warning_at (loc, OPT_Wmismatched_dealloc,
4058 "%qD called on pointer %qE passed to mismatched "
4059 "allocation function %qD",
4060 dealloc_decl, ptr, realloc_decl))
4061 return false;
4062 if (!ptr && !warning_at (loc, OPT_Wmismatched_dealloc,
4063 "%qD called on a pointer passed to mismatched "
4064 "reallocation function %qD",
4065 dealloc_decl, realloc_decl))
4066 return false;
4068 inform (gimple_location (realloc_stmt),
4069 "call to %qD", realloc_decl);
4070 return true;
4073 /* Return true if P and Q point to the same object, and false if they
4074 either don't or their relationship cannot be determined. */
4076 static bool
4077 pointers_related_p (gimple *stmt, tree p, tree q, pointer_query &qry,
4078 auto_bitmap &visited)
4080 if (!ptr_derefs_may_alias_p (p, q))
4081 return false;
4083 /* TODO: Work harder to rule out relatedness. */
4084 access_ref pref, qref;
4085 if (!qry.get_ref (p, stmt, &pref, 0)
4086 || !qry.get_ref (q, stmt, &qref, 0))
4087 /* GET_REF() only rarely fails. When it does, it's likely because
4088 it involves a self-referential PHI. Return a conservative result. */
4089 return false;
4091 if (pref.ref == qref.ref)
4092 return true;
4094 /* If either pointer is a PHI, iterate over all its operands and
4095 return true if they're all related to the other pointer. */
4096 tree ptr = q;
4097 unsigned version;
4098 gphi *phi = pref.phi ();
4099 if (phi)
4100 version = SSA_NAME_VERSION (pref.ref);
4101 else
4103 phi = qref.phi ();
4104 if (!phi)
4105 return false;
4107 ptr = p;
4108 version = SSA_NAME_VERSION (qref.ref);
4111 if (!bitmap_set_bit (visited, version))
4112 return true;
4114 unsigned nargs = gimple_phi_num_args (phi);
4115 for (unsigned i = 0; i != nargs; ++i)
4117 tree arg = gimple_phi_arg_def (phi, i);
4118 if (!pointers_related_p (stmt, arg, ptr, qry, visited))
4119 return false;
4122 return true;
4125 /* Convenience wrapper for the above. */
4127 static bool
4128 pointers_related_p (gimple *stmt, tree p, tree q, pointer_query &qry)
4130 auto_bitmap visited;
4131 return pointers_related_p (stmt, p, q, qry, visited);
4134 /* For a STMT either a call to a deallocation function or a clobber, warn
4135 for uses of the pointer PTR it was called with (including its copies
4136 or others derived from it by pointer arithmetic). If STMT is a clobber,
4137 VAR is the decl of the clobbered variable. When MAYBE is true use
4138 a "maybe" form of diagnostic. */
4140 void
4141 pass_waccess::check_pointer_uses (gimple *stmt, tree ptr,
4142 tree var /* = NULL_TREE */,
4143 bool maybe /* = false */)
4145 gcc_assert (TREE_CODE (ptr) == SSA_NAME);
4147 const bool check_dangling = !is_gimple_call (stmt);
4148 basic_block stmt_bb = gimple_bb (stmt);
4150 /* If STMT is a reallocation function set to the reallocated pointer
4151 and the LHS of the call, respectively. */
4152 tree realloc_ptr = NULL_TREE;
4153 tree realloc_lhs = get_realloc_lhs (stmt, &realloc_ptr);
4155 auto_bitmap visited;
4157 auto_vec<tree> pointers;
4158 pointers.safe_push (ptr);
4160 /* Starting with PTR, iterate over POINTERS added by the loop, and
4161 either warn for their uses in basic blocks dominated by the STMT
4162 or in statements that follow it in the same basic block, or add
4163 them to POINTERS if they point into the same object as PTR (i.e.,
4164 are obtained by pointer arithmetic on PTR). */
4165 for (unsigned i = 0; i != pointers.length (); ++i)
4167 tree ptr = pointers[i];
4168 if (!bitmap_set_bit (visited, SSA_NAME_VERSION (ptr)))
4169 /* Avoid revisiting the same pointer. */
4170 continue;
4172 use_operand_p use_p;
4173 imm_use_iterator iter;
4174 FOR_EACH_IMM_USE_FAST (use_p, iter, ptr)
4176 gimple *use_stmt = USE_STMT (use_p);
4177 if (use_stmt == stmt || is_gimple_debug (use_stmt))
4178 continue;
4180 if (realloc_lhs)
4182 /* Check to see if USE_STMT is a mismatched deallocation
4183 call for the pointer passed to realloc. That's a bug
4184 regardless of the pointer's value and so warn. */
4185 if (maybe_warn_mismatched_realloc (*use_p->use, stmt, use_stmt))
4186 continue;
4188 /* Pointers passed to realloc that are used in basic blocks
4189 where the realloc call is known to have failed are valid.
4190 Ignore pointers that nothing is known about. Those could
4191 have escaped along with their nullness. */
4192 value_range vr;
4193 if (m_ptr_qry.rvals->range_of_expr (vr, realloc_lhs, use_stmt))
4195 if (vr.zero_p ())
4196 continue;
4198 if (!pointers_related_p (stmt, ptr, realloc_ptr, m_ptr_qry))
4199 continue;
4203 if (check_dangling
4204 && gimple_code (use_stmt) == GIMPLE_RETURN)
4205 /* Avoid interfering with -Wreturn-local-addr (which runs only
4206 with optimization enabled so it won't diagnose cases that
4207 would be caught here when optimization is disabled). */
4208 continue;
4210 bool equality = false;
4211 if (is_gimple_assign (use_stmt))
4213 tree_code code = gimple_assign_rhs_code (use_stmt);
4214 equality = code == EQ_EXPR || code == NE_EXPR;
4216 else if (gcond *cond = dyn_cast<gcond *>(use_stmt))
4218 tree_code code = gimple_cond_code (cond);
4219 equality = code == EQ_EXPR || code == NE_EXPR;
4222 /* Warn if USE_STMT is dominated by the deallocation STMT.
4223 Otherwise, add the pointer to POINTERS so that the uses
4224 of any other pointers derived from it can be checked. */
4225 if (use_after_inval_p (stmt, use_stmt, check_dangling))
4227 if (gimple_code (use_stmt) == GIMPLE_PHI)
4229 /* Only add a PHI result to POINTERS if all its
4230 operands are related to PTR, otherwise continue. */
4231 tree lhs = gimple_phi_result (use_stmt);
4232 if (!pointers_related_p (stmt, lhs, ptr, m_ptr_qry))
4233 continue;
4235 if (TREE_CODE (lhs) == SSA_NAME)
4237 pointers.safe_push (lhs);
4238 continue;
4242 basic_block use_bb = gimple_bb (use_stmt);
4243 bool this_maybe
4244 = (maybe
4245 || !dominated_by_p (CDI_POST_DOMINATORS, stmt_bb, use_bb));
4246 warn_invalid_pointer (*use_p->use, use_stmt, stmt, var,
4247 this_maybe, equality);
4248 continue;
4251 if (is_gimple_assign (use_stmt))
4253 tree lhs = gimple_assign_lhs (use_stmt);
4254 if (TREE_CODE (lhs) == SSA_NAME)
4256 tree_code rhs_code = gimple_assign_rhs_code (use_stmt);
4257 if (rhs_code == POINTER_PLUS_EXPR || rhs_code == SSA_NAME)
4258 pointers.safe_push (lhs);
4260 continue;
4263 if (gcall *call = dyn_cast <gcall *>(use_stmt))
4265 if (gimple_call_return_arg (call) == ptr)
4266 if (tree lhs = gimple_call_lhs (call))
4267 if (TREE_CODE (lhs) == SSA_NAME)
4268 pointers.safe_push (lhs);
4269 continue;
4275 /* Check call STMT for invalid accesses. */
4277 void
4278 pass_waccess::check_call (gcall *stmt)
4280 if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
4281 check_builtin (stmt);
4283 /* .ASAN_MARK doesn't access any vars, only modifies shadow memory. */
4284 if (gimple_call_internal_p (stmt)
4285 && gimple_call_internal_fn (stmt) == IFN_ASAN_MARK)
4286 return;
4288 if (!m_early_checks_p)
4289 if (tree callee = gimple_call_fndecl (stmt))
4291 /* Check for uses of the pointer passed to either a standard
4292 or a user-defined deallocation function. */
4293 unsigned argno = fndecl_dealloc_argno (callee);
4294 if (argno < (unsigned) call_nargs (stmt))
4296 tree arg = call_arg (stmt, argno);
4297 if (TREE_CODE (arg) == SSA_NAME)
4298 check_pointer_uses (stmt, arg);
4302 check_call_access (stmt);
4303 check_call_dangling (stmt);
4305 if (m_early_checks_p)
4306 return;
4308 maybe_check_dealloc_call (stmt);
4309 check_nonstring_args (stmt);
4313 /* Return true of X is a DECL with automatic storage duration. */
4315 static inline bool
4316 is_auto_decl (tree x)
4318 return DECL_P (x) && !DECL_EXTERNAL (x) && !TREE_STATIC (x);
4321 /* Check non-call STMT for invalid accesses. */
4323 void
4324 pass_waccess::check_stmt (gimple *stmt)
4326 if (m_check_dangling_p
4327 && gimple_clobber_p (stmt, CLOBBER_EOL))
4329 /* Ignore clobber statements in blocks with exceptional edges. */
4330 basic_block bb = gimple_bb (stmt);
4331 edge e = EDGE_PRED (bb, 0);
4332 if (e->flags & EDGE_EH)
4333 return;
4335 tree var = gimple_assign_lhs (stmt);
4336 m_clobbers.put (var, stmt);
4337 return;
4340 if (is_gimple_assign (stmt))
4342 /* Clobbered unnamed temporaries such as compound literals can be
4343 revived. Check for an assignment to one and remove it from
4344 M_CLOBBERS. */
4345 tree lhs = gimple_assign_lhs (stmt);
4346 while (handled_component_p (lhs))
4347 lhs = TREE_OPERAND (lhs, 0);
4349 if (is_auto_decl (lhs))
4350 m_clobbers.remove (lhs);
4351 return;
4354 if (greturn *ret = dyn_cast <greturn *> (stmt))
4356 if (optimize && flag_isolate_erroneous_paths_dereference)
4357 /* Avoid interfering with -Wreturn-local-addr (which runs only
4358 with optimization enabled). */
4359 return;
4361 tree arg = gimple_return_retval (ret);
4362 if (!arg || TREE_CODE (arg) != ADDR_EXPR)
4363 return;
4365 arg = TREE_OPERAND (arg, 0);
4366 while (handled_component_p (arg))
4367 arg = TREE_OPERAND (arg, 0);
4369 if (!is_auto_decl (arg))
4370 return;
4372 gimple **pclobber = m_clobbers.get (arg);
4373 if (!pclobber)
4374 return;
4376 if (!use_after_inval_p (*pclobber, stmt))
4377 return;
4379 warn_invalid_pointer (NULL_TREE, stmt, *pclobber, arg, false);
4383 /* Check basic block BB for invalid accesses. */
4385 void
4386 pass_waccess::check_block (basic_block bb)
4388 /* Iterate over statements, looking for function calls. */
4389 for (auto si = gsi_start_bb (bb); !gsi_end_p (si);
4390 gsi_next_nondebug (&si))
4392 gimple *stmt = gsi_stmt (si);
4393 if (gcall *call = dyn_cast <gcall *> (stmt))
4394 check_call (call);
4395 else
4396 check_stmt (stmt);
4400 /* Return the argument that the call STMT to a built-in function returns
4401 (including with an offset) or null if it doesn't. */
4403 tree
4404 pass_waccess::gimple_call_return_arg (gcall *call)
4406 /* Check for attribute fn spec to see if the function returns one
4407 of its arguments. */
4408 attr_fnspec fnspec = gimple_call_fnspec (call);
4409 unsigned int argno;
4410 if (!fnspec.returns_arg (&argno))
4412 if (gimple_call_num_args (call) < 1)
4413 return NULL_TREE;
4415 if (!gimple_call_builtin_p (call, BUILT_IN_NORMAL))
4416 return NULL_TREE;
4418 tree fndecl = gimple_call_fndecl (call);
4419 switch (DECL_FUNCTION_CODE (fndecl))
4421 case BUILT_IN_MEMPCPY:
4422 case BUILT_IN_MEMPCPY_CHK:
4423 case BUILT_IN_MEMCHR:
4424 case BUILT_IN_STRCHR:
4425 case BUILT_IN_STRRCHR:
4426 case BUILT_IN_STRSTR:
4427 case BUILT_IN_STPCPY:
4428 case BUILT_IN_STPCPY_CHK:
4429 case BUILT_IN_STPNCPY:
4430 case BUILT_IN_STPNCPY_CHK:
4431 argno = 0;
4432 break;
4434 default:
4435 return NULL_TREE;
4439 if (gimple_call_num_args (call) <= argno)
4440 return NULL_TREE;
4442 return gimple_call_arg (call, argno);
4445 /* Return the decl referenced by the argument that the call STMT to
4446 a built-in function returns (including with an offset) or null if
4447 it doesn't. */
4449 tree
4450 pass_waccess::gimple_call_return_arg_ref (gcall *call)
4452 if (tree arg = gimple_call_return_arg (call))
4454 access_ref aref;
4455 if (m_ptr_qry.get_ref (arg, call, &aref, 0)
4456 && DECL_P (aref.ref))
4457 return aref.ref;
4460 return NULL_TREE;
4463 /* Check for and diagnose all uses of the dangling pointer VAR to the auto
4464 object DECL whose lifetime has ended. OBJREF is true when VAR denotes
4465 an access to a DECL that may have been clobbered. */
4467 void
4468 pass_waccess::check_dangling_uses (tree var, tree decl, bool maybe /* = false */,
4469 bool objref /* = false */)
4471 if (!decl || !is_auto_decl (decl))
4472 return;
4474 gimple **pclob = m_clobbers.get (decl);
4475 if (!pclob)
4476 return;
4478 if (!objref)
4480 check_pointer_uses (*pclob, var, decl, maybe);
4481 return;
4484 gimple *use_stmt = SSA_NAME_DEF_STMT (var);
4485 if (!use_after_inval_p (*pclob, use_stmt, true))
4486 return;
4488 basic_block use_bb = gimple_bb (use_stmt);
4489 basic_block clob_bb = gimple_bb (*pclob);
4490 maybe = maybe || !dominated_by_p (CDI_POST_DOMINATORS, clob_bb, use_bb);
4491 warn_invalid_pointer (var, use_stmt, *pclob, decl, maybe, false);
4494 /* Diagnose stores in BB and (recursively) its predecessors of the addresses
4495 of local variables into nonlocal pointers that are left dangling after
4496 the function returns. BBS is a bitmap of basic blocks visited. */
4498 void
4499 pass_waccess::check_dangling_stores (basic_block bb,
4500 hash_set<tree> &stores,
4501 auto_bitmap &bbs)
4503 if (!bitmap_set_bit (bbs, bb->index))
4504 /* Avoid cycles. */
4505 return;
4507 /* Iterate backwards over the statements looking for a store of
4508 the address of a local variable into a nonlocal pointer. */
4509 for (auto gsi = gsi_last_nondebug_bb (bb); ; gsi_prev_nondebug (&gsi))
4511 gimple *stmt = gsi_stmt (gsi);
4512 if (!stmt)
4513 break;
4515 if (warning_suppressed_p (stmt, OPT_Wdangling_pointer_))
4516 continue;
4518 if (is_gimple_call (stmt)
4519 && !(gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE)))
4520 /* Avoid looking before nonconst, nonpure calls since those might
4521 use the escaped locals. */
4522 return;
4524 if (!is_gimple_assign (stmt) || gimple_clobber_p (stmt))
4525 continue;
4527 access_ref lhs_ref;
4528 tree lhs = gimple_assign_lhs (stmt);
4529 if (!m_ptr_qry.get_ref (lhs, stmt, &lhs_ref, 0))
4530 continue;
4532 if (is_auto_decl (lhs_ref.ref))
4533 continue;
4535 if (DECL_P (lhs_ref.ref))
4537 if (!POINTER_TYPE_P (TREE_TYPE (lhs_ref.ref))
4538 || lhs_ref.deref > 0)
4539 continue;
4541 else if (TREE_CODE (lhs_ref.ref) == SSA_NAME)
4543 gimple *def_stmt = SSA_NAME_DEF_STMT (lhs_ref.ref);
4544 if (!gimple_nop_p (def_stmt))
4545 /* Avoid looking at or before stores into unknown objects. */
4546 return;
4548 tree var = SSA_NAME_VAR (lhs_ref.ref);
4549 if (TREE_CODE (var) == PARM_DECL && DECL_BY_REFERENCE (var))
4550 /* Avoid by-value arguments transformed into by-reference. */
4551 continue;
4554 else if (TREE_CODE (lhs_ref.ref) == MEM_REF)
4556 tree arg = TREE_OPERAND (lhs_ref.ref, 0);
4557 if (TREE_CODE (arg) == SSA_NAME)
4559 gimple *def_stmt = SSA_NAME_DEF_STMT (arg);
4560 if (!gimple_nop_p (def_stmt))
4561 return;
4564 else
4565 continue;
4567 if (stores.add (lhs_ref.ref))
4568 continue;
4570 /* FIXME: Handle stores of alloca() and VLA. */
4571 access_ref rhs_ref;
4572 tree rhs = gimple_assign_rhs1 (stmt);
4573 if (!m_ptr_qry.get_ref (rhs, stmt, &rhs_ref, 0)
4574 || rhs_ref.deref != -1)
4575 continue;
4577 if (!is_auto_decl (rhs_ref.ref))
4578 continue;
4580 location_t loc = gimple_location (stmt);
4581 if (warning_at (loc, OPT_Wdangling_pointer_,
4582 "storing the address of local variable %qD in %qE",
4583 rhs_ref.ref, lhs))
4585 suppress_warning (stmt, OPT_Wdangling_pointer_);
4587 location_t loc = DECL_SOURCE_LOCATION (rhs_ref.ref);
4588 inform (loc, "%qD declared here", rhs_ref.ref);
4590 if (DECL_P (lhs_ref.ref))
4591 loc = DECL_SOURCE_LOCATION (lhs_ref.ref);
4592 else if (EXPR_HAS_LOCATION (lhs_ref.ref))
4593 loc = EXPR_LOCATION (lhs_ref.ref);
4595 if (loc != UNKNOWN_LOCATION)
4596 inform (loc, "%qE declared here", lhs_ref.ref);
4600 edge e;
4601 edge_iterator ei;
4602 FOR_EACH_EDGE (e, ei, bb->preds)
4604 basic_block pred = e->src;
4605 check_dangling_stores (pred, stores, bbs);
4609 /* Diagnose stores of the addresses of local variables into nonlocal
4610 pointers that are left dangling after the function returns. */
4612 void
4613 pass_waccess::check_dangling_stores ()
4615 auto_bitmap bbs;
4616 hash_set<tree> stores;
4617 check_dangling_stores (EXIT_BLOCK_PTR_FOR_FN (m_func), stores, bbs);
4620 /* Check for and diagnose uses of dangling pointers to auto objects
4621 whose lifetime has ended. */
4623 void
4624 pass_waccess::check_dangling_uses ()
4626 tree var;
4627 unsigned i;
4628 FOR_EACH_SSA_NAME (i, var, m_func)
4630 /* For each SSA_NAME pointer VAR find the DECL it points to.
4631 If the DECL is a clobbered local variable, check to see
4632 if any of VAR's uses (or those of other pointers derived
4633 from VAR) happens after the clobber. If so, warn. */
4634 tree decl = NULL_TREE;
4636 gimple *def_stmt = SSA_NAME_DEF_STMT (var);
4637 if (is_gimple_assign (def_stmt))
4639 tree rhs = gimple_assign_rhs1 (def_stmt);
4640 if (TREE_CODE (rhs) == ADDR_EXPR)
4642 if (!POINTER_TYPE_P (TREE_TYPE (var)))
4643 continue;
4644 decl = TREE_OPERAND (rhs, 0);
4646 else
4648 /* For other expressions, check the base DECL to see
4649 if it's been clobbered, most likely as a result of
4650 inlining a reference to it. */
4651 decl = get_base_address (rhs);
4652 if (DECL_P (decl))
4653 check_dangling_uses (var, decl, false, true);
4654 continue;
4657 else if (POINTER_TYPE_P (TREE_TYPE (var)))
4659 if (gcall *call = dyn_cast<gcall *>(def_stmt))
4660 decl = gimple_call_return_arg_ref (call);
4661 else if (gphi *phi = dyn_cast <gphi *>(def_stmt))
4663 unsigned nargs = gimple_phi_num_args (phi);
4664 for (unsigned i = 0; i != nargs; ++i)
4666 access_ref aref;
4667 tree arg = gimple_phi_arg_def (phi, i);
4668 if (!m_ptr_qry.get_ref (arg, phi, &aref, 0)
4669 || (aref.deref == 0
4670 && POINTER_TYPE_P (TREE_TYPE (aref.ref))))
4671 continue;
4672 check_dangling_uses (var, aref.ref, true);
4674 continue;
4676 else
4677 continue;
4680 check_dangling_uses (var, decl);
4684 /* Check CALL arguments for dangling pointers (those that have been
4685 clobbered) and warn if found. */
4687 void
4688 pass_waccess::check_call_dangling (gcall *call)
4690 unsigned nargs = gimple_call_num_args (call);
4691 for (unsigned i = 0; i != nargs; ++i)
4693 tree arg = gimple_call_arg (call, i);
4694 if (TREE_CODE (arg) != ADDR_EXPR)
4695 continue;
4697 arg = TREE_OPERAND (arg, 0);
4698 if (!DECL_P (arg))
4699 continue;
4701 gimple **pclobber = m_clobbers.get (arg);
4702 if (!pclobber)
4703 continue;
4705 if (!use_after_inval_p (*pclobber, call))
4706 continue;
4708 warn_invalid_pointer (NULL_TREE, call, *pclobber, arg, false);
4712 /* Check function FUN for invalid accesses. */
4714 unsigned
4715 pass_waccess::execute (function *fun)
4717 calculate_dominance_info (CDI_DOMINATORS);
4718 calculate_dominance_info (CDI_POST_DOMINATORS);
4720 /* Set or clear EDGE_DFS_BACK bits on back edges. */
4721 mark_dfs_back_edges (fun);
4723 /* Create a new ranger instance and associate it with FUN. */
4724 m_ptr_qry.rvals = enable_ranger (fun);
4725 m_func = fun;
4727 /* Check for dangling pointers in the earliest run of the pass.
4728 The latest point -Wdangling-pointer should run is just before
4729 loop unrolling which introduces uses after clobbers. Most cases
4730 can be detected without optimization; cases where the address of
4731 the local variable is passed to and then returned from a user-
4732 defined function before its lifetime ends and the returned pointer
4733 becomes dangling depend on inlining. */
4734 m_check_dangling_p = m_early_checks_p;
4736 auto_bitmap bb_uids_set (&bitmap_default_obstack);
4737 m_bb_uids_set = bb_uids_set;
4739 set_gimple_stmt_max_uid (m_func, 0);
4741 basic_block bb;
4742 FOR_EACH_BB_FN (bb, fun)
4743 check_block (bb);
4745 if (m_check_dangling_p)
4747 check_dangling_uses ();
4748 check_dangling_stores ();
4751 if (dump_file)
4752 m_ptr_qry.dump (dump_file, (dump_flags & TDF_DETAILS) != 0);
4754 m_ptr_qry.flush_cache ();
4756 /* Release the ranger instance and replace it with a global ranger.
4757 Also reset the pointer since calling disable_ranger() deletes it. */
4758 disable_ranger (fun);
4759 m_ptr_qry.rvals = NULL;
4761 m_clobbers.empty ();
4762 m_bb_uids_set = NULL;
4764 free_dominance_info (CDI_POST_DOMINATORS);
4765 free_dominance_info (CDI_DOMINATORS);
4766 return 0;
4769 } // namespace
4771 /* Return a new instance of the pass. */
4773 gimple_opt_pass *
4774 make_pass_warn_access (gcc::context *ctxt)
4776 return new pass_waccess (ctxt);