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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/107259] New: Vectorize VxHF _Float16 modes using partial
 vectors without -mavx512vl
Date: Fri, 14 Oct 2022 09:06:00 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 12.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: ubizjak at gmail dot com
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107259

            Bug ID: 107259
           Summary: Vectorize VxHF _Float16 modes using partial vectors
                    without -mavx512vl
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ubizjak at gmail dot com
  Target Milestone: ---

The following testcase:

--cut here--
#define N 16

_Float16 r[N], a[N], b[N];

void foo (void)
{
  for (int i =3D 0; i < N; i++)
    r[i] =3D a[i] + b[i];
}
--cut here--

can be vectorized with -O2 -mavx512fp16 -mavx512vl, but not when -mavx512vl=
 is
omitted. However, the test can still be vectorized using partial vectors.

The testcase should be vectorized for all N < 32, even without -mavx512vl.=