[Bug target/79299] New: [7 Regression] Operand size mismatch for `vpgatherqd' w/ -O3 -masm=intel -mavx512bw

["asolokha at gmx dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79299

            Bug ID: 79299
           Summary: [7 Regression] Operand size mismatch for `vpgatherqd'
                    w/ -O3 -masm=intel -mavx512bw
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: assemble-failure
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: x86_64-pc-linux-gnu

When compiling the following snippet w/ -O3 -masm=intel -mavx512bw (and other
flavors of AVX-512) using gcc-7.0.0-alpha20170129 snapshot, gas 2.27 emits the
"operand size mismatch" error for instruction vpgatherqd:

int
q9 (int b7, int dr)
{
  int **ov;
  int rk = &b7;

  while (dr != 0)
    {
      while (b7 != 0)
        ++b7;
      rk += **ov;
      ++dr;
    }

  return rk;
}

% x86_64-pc-linux-gnu-gcc-7.0.0-alpha20170129 -O3 -masm=intel -mavx512bw -c -w
xivubswo.c
/tmp/cc27Zzec.s: Assembler messages:
/tmp/cc27Zzec.s:38: Error: operand size mismatch for `vpgatherqd'
/tmp/cc27Zzec.s:39: Error: operand size mismatch for `vpgatherqd'