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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/107107] Wrong codegen from TBAA when stores to
 distinct same-mode types are collapsed?
Date: Sat, 01 Oct 2022 02:59:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107107

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. I don't think it is exactly TBAA which is causing the issue but
rather the way PRE does aliasing walks.

Take:
```
static inline void set_longish(int is_long, void *p, long x)
{
    if (is_long)
        *(long*)p =3D x;
    else
        *(long long*)p =3D x;
}
static long test(long long *p, int index, int mode)
{
    *p =3D 1;
    set_longish(mode, p+index, 2);
    return *p;
}
long (*volatile vtest)(long long*, int, int) =3D test;
#include <stdio.h>
int main(void)
{
    long long x;
    long result =3D vtest(&x, 0, 0);
    printf("%lu/%llu\n", result, x);
}
```
Which is only difference by which order the if statement (and mode which is
swapped). This case works.=