https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92397
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-11-06
CC| |msebor at gcc dot gnu.org
Component|c |bootstrap
Blocks| |56456, 86656
Ever confirmed|0 |1
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
The excessive sanitizer instrumentation is known to cause trouble for
middle-end warnings like -Warray-bounds (see for example pr91146, pr91707,
pr87884, pr84863, pr81601, and others). The sanitized VRP dump for
real_roundeven shows the out-of-bounds indices:
<bb 2> [local count: 1073741823]:
retval.467_13 = is_halfway_below (x_11(D));
if (retval.467_13 != 0)
goto <bb 3>; [67.00%]
else
goto <bb 9>; [33.00%]
<bb 3> [local count: 719407020]:
.UBSAN_NULL (x_11(D), 3B, 8);
_1 = BIT_FIELD_REF <*x_11(D), 32, 0>;
_2 = _1 & 4294967232;
if (_2 == 0)
goto <bb 4>; [50.00%]
else
goto <bb 5>; [50.00%]
<bb 4> [local count: 359703513]:
.UBSAN_NULL (x_11(D), 2B, 8);
.UBSAN_NULL (r_14(D), 1B, 8);
.UBSAN_NULL (x_11(D), 0B, 8);
_23 = __builtin_object_size (r_14(D), 0);
GIMPLE_NOP
_24 = __builtin_object_size (x_11(D), 0);
GIMPLE_NOP
*r_14(D) = *x_11(D);
.UBSAN_NULL (r_14(D), 3B, 8);
_48 = __builtin_object_size (r_14(D), 0);
_49 = &r_14(D)->sig[0];
_56 = (unsigned long) _49;
_57 = (unsigned long) r_14(D);
_58 = _56 - _57;
_60 = _58 + 8;
GIMPLE_NOP
.UBSAN_PTR (r_14(D), 8);
r_14(D)->sig[0] = 0;
.UBSAN_NULL (r_14(D), 3B, 8);
_92 = __builtin_object_size (r_14(D), 0);
_93 = &r_14(D)->sig[1];
_94 = (unsigned long) _93;
_96 = _94 - _57;
_97 = _96 + 8;
GIMPLE_NOP
.UBSAN_PTR (r_14(D), 16);
r_14(D)->sig[1] = 0;
.UBSAN_NULL (r_14(D), 3B, 8);
_108 = __builtin_object_size (r_14(D), 0);
_109 = &r_14(D)->sig[2];
_110 = (unsigned long) _109;
_112 = _110 - _57;
_113 = _112 + 8;
GIMPLE_NOP
.UBSAN_PTR (r_14(D), 24);
r_14(D)->sig[2] = 0;
.UBSAN_NULL (r_14(D), 3B, 8);
_50 = __builtin_object_size (r_14(D), 0);
_51 = &r_14(D)->sig[3]; <<< out of bounds
_52 = (unsigned long) _51;
_54 = _52 - _57;
_55 = _54 + 8;
GIMPLE_NOP
.UBSAN_PTR (r_14(D), 32);
_59 = r_14(D)->sig[3]; <<< out of bounds
.UBSAN_NULL (r_14(D), 3B, 8);
_61 = __builtin_object_size (r_14(D), 0);
GIMPLE_NOP
.UBSAN_PTR (r_14(D), 32);
goto <bb 7>; [100.00%]
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56456
[Bug 56456] [meta-bug] bogus/missing -Warray-bounds
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86656
[Bug 86656] [meta-bug] Issues found with -fsanitize=address
