This patch adds support for the vector quadword add/sub instructions introduced in POWER8:
- vadduqm
- vaddeuqm
- vaddcuq
- vaddecuq
- vsubuqm
- vsubeuqm
- vsubcuq
- vsubecuq
In addition to adding the instructions themselves, it also adds support for the v1i128 type for intrinsics (Intrinsics.td, Function.cpp, and IntrinsicEmitter.cpp).
Do we not want these guarded for Power8 Altivec feature? It would seem that we don't want these available in the back end for CPU's that don't have the feature.