https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107912
Bug ID: 107912
Summary: UBsan at -O0 missed a signed integer overflow
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at
gcc dot gnu.org
Target Milestone: ---
`gcc-trunk -O0 -fsanitize=undefined -fno-sanitize-recover=all` misses the
signed integer overflow, while `gcc-trunk -Ox -fsanitize=address
-fno-sanitize-recover=all` (x=1, 2, 3, or s) can detect it.
Compiler explorer: https://godbolt.org/z/n8qs3z6v4
% cat a.c
unsigned short a;
int b;
int main() {
int c = b = -2147483648;
a = (c && 0 == c) - b;
__builtin_printf("%d\n", a);
}
%
% gcc-tk -O0 -fsanitize=undefined -fno-sanitize-recover=all a.c &&./a.out
0
% gcc-tk -O1 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
a.c:5:21: runtime error: negation of -2147483648 cannot be represented in type
'int'; cast to an unsigned type to negate this value to itself
% gcc-tk -O3 -fsanitize=undefined -fno-sanitize-recover=all -w a.c &&./a.out
a.c:5:21: runtime error: negation of -2147483648 cannot be represented in type
'int'; cast to an unsigned type to negate this value to itself
%
