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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug driver/109605] -fno-tree-vectorize does not disable vectorizer
Date: Wed, 17 May 2023 18:08:28 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109605

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-05-17
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

Take a simple LP64 testcase (just to make the aliasing happy):
```
int f1(long long *a, long *b, long *c)
{
        long a0, a1;
        a[0] =3D b[0] + c[0];
        a[1] =3D b[1] + c[1];
}
```
At `-O2`, SLP vectorizers it.
`-O2 -fno-tree-vectorize` disables the SLP vectorizer
But if you did:
`-O2 -ftree-slp-vectorize -fno-tree-vectorize` the SLP vectorizer is turned=
 on
still. This is what is definitely counter-intuitive really.=