case UNW_X86_64_R14: return &mcontext->gregs[REG_R14];
case UNW_X86_64_R15: return &mcontext->gregs[REG_R15];
case UNW_X86_64_RIP: return &mcontext->gregs[REG_RIP];
case UNW_X86_64_R14: return &mcontext->gregs[REG_R14];
case UNW_X86_64_R15: return &mcontext->gregs[REG_R15];
case UNW_X86_64_RIP: return &mcontext->gregs[REG_RIP];