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Re: DFA for PPro, P2, P3
On Thu, May 02, 2002 at 08:28:48PM -0600, firstname.lastname@example.org wrote:
> That's one of the things that is (to me at least) extremely unclear about
> the PPro/P2/P3 pipeline -- ordering/dependency of uops.
Well it's quite clear that a load-execute x86 insn (as your example
must have been) will consist of a load uop plus an execute uop, and
it is quite clear that the two must be data dependent.
Now, the execute uop may not be executed immediately after the load
uop, but I think for all practical purposes on an OOO machine
reserving the resource is good enough, since that pretty much
guarantees that at least as many resources as you reserved will
be available, so it won't run any slower.
But (p0|p1)+p0 makes no sense no matter how you slice it.
What does p0+p0 mean, after all? Deadlock.