On Mon, Mar 18, 2019 at 01:13:32PM +0100, David Brown wrote: > But you have to realise that neither the compiler nor the assembler is > changing anything here. "mftb" is not an instruction in its own right > on most PPC cores It exists on *all* CPUs. It has been a basic mnemonic since PowerPC 1.xx, and it is still part of Power ISA 3.0B. (POWER had 5-bit SPRs, not 10-bit, btw -- and no TB either, there was an RTC instead). Segher
