There were some patterns, like 0x0000_ffff_ffff_00ff, for which we
would select to begin a multi-insn sequence with MOVN, but would
fail to set the 0x0000 lane back from 0xffff.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Message-Id: <20161207180727.6286-3-rth@twiddle.net>
(cherry picked from commit 8cf9a3d3)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>