Currently, disassembler test files for mips64r6 report errors for double word addition instructions(dadd, daddi). The resaon is that in command line options triple is set to mips instead of mips64. When this is changed error is reported for r6 instructions as the disassembler tables for them are not used. This patch adds r6 instructions to disassembler for mips64 and fixes the test files to use mips64 triple. Double word addition test cases are added also.
Your change looks good to me but I think there's a better way to resolve this. I think it's wrong for us to have separate Mips32 and Mips64 disassemblers and for the target triple to have an effect on the behaviour (it should be the ELF header rather than the triple). I've uploaded http://reviews.llvm.org/D7498 which folds the two disassembler classes into a single class which I believe does the right thing for Mips32 and Mips64.