[PPC64] Add vector pack/unpack support from ISA 2.07

This patch adds support for the following new instructions in the
Power ISA 2.07:

  vpksdss
  vpksdus
  vpkudus
  vpkudum
  vupkhsw
  vupklsw

These instructions are available through the vec_packs, vec_packsu,
vec_unpackh, and vec_unpackl built-in interfaces.  These are
lane-sensitive instructions, so the built-ins have different
implementations for big- and little-endian, and the instructions must
be marked as killing the vector swap optimization for now.

The first three instructions perform saturating pack operations.  The
fourth performs a modulo pack operation, which means it can be
represented with a vector shuffle, and conversely the appropriate
vector shuffles may cause this instruction to be generated.  The other
instructions are only generated via built-in support for now.

I noticed during patch preparation that the macro __VSX__ was not
previously predefined when the power8-vector or direct-move features
are requested.  This is an error, and I've corrected that here as
well.

Appropriate tests have been added.

There is a companion patch to llvm for the rest of this support.

llvm-svn: 237500

0 files changed, 0 insertions, 0 deletions