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Re: DFA for PPro, P2, P3
- From: law at redhat dot com
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 02 May 2002 20:28:48 -0600
- Subject: Re: DFA for PPro, P2, P3
- Reply-to: law at redhat dot com
In message <20020502170825.B5227@redhat.com>, Richard Henderson writes:
> On Thu, May 02, 2002 at 04:55:46PM -0600, firstname.lastname@example.org wrote:
> > (define_insn_reservation <latency>
> > <attribute test to select the insn type for I2>
> > "(p0|p1)+p0")
> Isn't that rather "(p0|p1),p0"? After all, the second uop
> doesn't issue on the same cycle.
That's one of the things that is (to me at least) extremely unclear about
the PPro/P2/P3 pipeline -- ordering/dependency of uops.
If you've got good documentation on this it's fairly trivial to change it;
in fact, the ability to model that kind of information is one of the
other key advantages of the DFA model.