https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118935
--- Comment #1 from chenglulu <chenglulu at loongson dot cn> ---
Upon debugging, it was discovered that if the '-O0' option is used to compile
the `find_file0` function in `libgfortran/io/unix.c`, random errors occur.
However, if the `find_file0` function is compiled with the '-O1' option, no
random errors arise.
The erroneous code is as follows:
libgfortran/io/unix.c
```
static gfc_unit *
find_file0 (gfc_unit *u, FIND_FILE0_DECL)
{
......
#ifdef HAVE_WORKING_STAT
if (u->s != NULL) // The input I provided next was: At this point, when
making the judgment, u->s is not NULL.
{
unix_stream *s = (unix_stream *) (u->s);
if (st[0].st_dev == s->st_dev && st[0].st_ino == s->st_ino) // But here
it is NULL，u->s has been modified.
return u;
}
```
The corresponding LoongArch assembly code here is as follows.
```
ld.d $r12,$r3,8
ld.d $r12,$r12,8
beqz $r12,.L4 // Here, $r12 is not NULL.
ld.d $r12,$r3,8
ld.d $r12,$r12,8 // However, when reloaded, it has already become
NULL.
st.d $r12,$r3,24
ldptr.d $r12,$r3,0
ldptr.d $r13,$r12,0
ld.d $r12,$r3,24
ld.d $r12,$r12,72
```
