On 2016-04-05, at 10:00, Swarbrick, Frank wrote: > Can I infer from this that XR/XGR, all else being equal, is to be preferred > (slightly) over LHI/LGHI? > If so, why might that be? I would have thought the one that doesn't touch > the CC would be "more efficient" than the one that does. > Or am I misreading your statement? > Instruction fetch bandwidth? Perhaps "don't care about the CC" implies that no instruction testing CC might be in the pipeline so lockout is not a concern.
> -----Original Message----- > From: Peter Relson > Sent: Monday, April 04, 2016 8:49 PM > > Relaying info on recommendation for clearing a reg > -- if you're doing a 32-bit GR clear and don't care about the CC or would > prefer the CC to be cleared, use XR > -- if you're doing a 64-bit GR clear and don't care about the CC or would > prefer the CC to be cleared, use XGR. > -- if you're doing a 32-bit GR clear and cannot destroy the CC, use LHI. > -- if you're doing a 64-bit GR clear and cannot destroy the CC, use LGHI. -- gil
