Re: cr logical insn implementation for rs6000

[David Edelsohn <dje at watson dot ibm dot com>]

>>>>> Geoff Keating writes:

Geoff> They're execute-synchronized according to the docs on the 604 and 750.
Geoff> I expect that they will usually have a latency of 3-4 cycles, as it'll
Geoff> take 2-3 cycles for the pipeline to flush.  There doesn't seem to be
Geoff> an easy way to explain execute-synchronization to the old scheduler,
Geoff> and I'm unwilling to spend much time on it when it'll all go away RSN
Geoff> with the DFA-based pipeline descriptions.

	The execution serialization of those instructions on the 604 and
750 cannot be generalized.  On the processors with a separate CR Logic
Unit, they are not serialized -- only those where they are in the Branch
Unit have the serialization.  I will fix this as well.

	What is the new DFA-based pipeline scheduler?

Geoff> If you happen to have a POWER3 data book handy, one that describes the
Geoff> instruction timings in detail, that'd be very useful.  Especially in
Geoff> PDF form...

	Unfortunately, the documents are IBM Confidential.  I work across
the hall from the person who maintains the documents for all IBM PowerPC
architectures, so it is easy for me to look up any details for any IBM
chip implementation.

Thanks, David