Slightly change TableGen's definition of a register subclass.
A subclass is allowed to have a larger spill size than the superclass, and the
spill alignment must be a multiple of the superclass alignment. This causes
the following new subclass relations:
=== Alpha ===
F4RC -> F8RC
=== PPC ===
F4RC -> F8RC
=== SPU ===
R8C -> R16C -> R32C/R32FP -> R64C/R64FP -> GPRC/VECREG
=== X86 ===
FR32 -> FR64 -> VR128
RFP32 -> RFP64 -> RFP80
These subclass relations are consistent with the behaviour of -join-cross-class-copies.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70511
91177308-0d34-0410-b5e6-
96231b3b80d8