ARM: add patterns for [su]xta[bh] from just a shift.

Although the final shifter operand is a rotate, this actually only matters for
the half-word extends when the amount == 24. Otherwise folding a shift in is
just as good.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213753 91177308-0d34-0410-b5e6-96231b3b80d8
ARM: spot SBFX-compatbile code expressed with sign_extend_inreg

We were assuming all SBFX-like operations would have the shl/asr form, but
often when the field being extracted is an i8 or i16, we end up with a
SIGN_EXTEND_INREG acting on a shift instead. Simple enough to check for though.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213754 91177308-0d34-0410-b5e6-96231b3b80d8
[SKX] Enabling mask instructions: encoding, lowering
KMOVB, KMOVW, KMOVD, KMOVQ, KNOTB, KNOTW, KNOTD, KNOTQ

Reviewed by Elena Demikhovsky <elena.demikhovsky@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213757 91177308-0d34-0410-b5e6-96231b3b80d8