https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107269
Bug ID: 107269
Summary: wrong code at -O1 and above with "-fno-tree-ccp" on
x86_64-linux-gnu
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhendong.su at inf dot ethz.ch
Target Milestone: ---
It appears to be a recent regression.
Compiler Explorer: https://godbolt.org/z/WdcsavxTh
[593] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
--with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20221014 (experimental) [master r13-3307-g8efc38347a7] (GCC)
[594] %
[594] % gcctk -O1 small.c; ./a.out
[595] %
[595] % gcctk -O1 -fno-tree-ccp small.c
[596] % ./a.out
Floating point exception
[597] %
[597] % cat small.c
int a, b, f;
char c = 3;
unsigned d = 1;
short e;
int main() {
int h = 2357999721;
char i = a = 3;
for (; a >= 0; a--) {
int *j = &h;
char k = i || c;
short l = ~h;
b = ~(d % h);
f = ~i / b;
if (h >= -1936967575) {
int m = h / d / 110000000 ^ (f & c);
short n = c;
if (h <= -1936967575)
n = e;
h = m;
c = ~(n + f);
d = -1;
}
i = ~l - k;
}
return 0;
}
