[Bug tree-optimization/93843] New: wrong code at -O3 on x86_64-linux-gnu
qrzhang at gatech dot edu
gcc-bugzilla@gcc.gnu.org
Thu Feb 20 06:07:00 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93843
Bug ID: 93843
Summary: wrong code at -O3 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: qrzhang at gatech dot edu
Target Milestone: ---
A recent regression. Gcc-9 works fine.
Bisection points to g:6271dd984d7f920d4fb17ad37af6a1f8e6b796dc
$ gcc-trunk -v
gcc version 10.0.1 20200219 (experimental) [master revision
665c5bad168:533e82edecf:51faf07cef9293af544bfacc7d0b320ab90d7d60] (GCC)
$ gcc-trunk -O3 abc.c ; ./a.out
4
0
$ gcc-9 -O3 abc.c ; ./a.out
4
4
$ gcc-trunk abc.c ; ./a.out
4
4
$ cat abc.c
int printf(const char *, ...);
char a, e;
struct {
short b;
short c;
} d;
int f;
int main() {
short *g = &d.c, *h = &d.b;
e = 4 - a;
*h = *g = e;
for (; f < 2; f++)
printf("%d\n", d.c);
}
More information about the Gcc-bugs
mailing list