We were able to assemble, but not disassemble. Note that fixupRMValue was truncating EA_REG_BND0-3 because we hit the uint8_t max. The control registers were already squarely above it, but I don't think they ever go in .r/m, only in .reg. I also did notice an extra REX.W in our encoding, but I think that's fine. llvm-svn: 275427