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From: "clyon at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114323] [14 Regression] MVE vector load intrinsic
 miscompiled since r14-5622-g4d7647edfd7d98
Date: Thu, 14 Mar 2024 07:44:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114323

Christophe Lyon <clyon at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-03-14
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1

--- Comment #2 from Christophe Lyon <clyon at gcc dot gnu.org> ---
Tried a similar testcase for aarch64 (the intrinsics framework for MVE is v=
ery
close to SVE's), and noticed that when running dse_classify_store() it sees=
 a
use of the initialized memory:

svuint32_t foo ()=20=20
{
  const uint32_t D.11583[4];
  svuint32_t V0;

<bb 2> :=20
 D.11583[0] =3D 1;=20
 D.11583[1] =3D 2;=20
 D.11583[2] =3D 3;=20
 D.11583[3] =3D 4;=20
 V0_7 =3D svld1_u32 ({ -1, 0, 0, 0, ... }, &D.11583);
 D.11583 =3D{v} {CLOBBER(eol)};
 return V0_7;
}

# .MEM_6 =3D VDEF <.MEM_
D.11583[3] =3D 4;
# VUSE <.MEM_6>
V0_7 =3D svld1_u32 ({ -1, 0, 0, 0, ... }, &D.11583);



dse_classify_store() on arm/MVE does not see such a use and decides the
initialization is a dead store.=