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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/106365] Miss to handle ifn .LEN_STORE in FRE
Date: Thu, 21 Jul 2022 07:39:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106365

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Kewen Lin from comment #10)
> But it still keeps the .LEN_STORE there:
>=20
> int foo ()
> {
>   int a[10];
>=20
>   <bb 2> [local count: 97603129]:
>   .LEN_STORE (&MEM <int[10]> [(void *)&a + 32B], 128B, 8, { 64, 0, 0, 0, =
81,
> 0, 0, 0, 100, 0, 0, 0, 121, 0, 0, 0 }, 0);
>   a =3D{v} {CLOBBER(eol)};
>   return 285;
>=20
> }
>=20
> btw, the latest commit "Add alias disambiguation for vectorizer load/store
> IFNs" has been applied.

I think that DSE doesn't handle the store IFNs yet - maybe adding handling
to initialize_ao_ref_for_dse would be enough - but I think it cannot yet
handle a "conservative" start (for .MASK_STORES), but .LEN_STORE should
be possible to describe exact by giving an exact trimmed size to ao_ref
(the alias disambiguation changes could be also made more precise there).

Can you open a separate bugreport for the DSE issue?=