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Scheduling automaton question
- From: Bernd Schmidt <bernds at codesourcery dot com>
- To: GCC List <gcc at gcc dot gnu dot org>
- Cc: "Vladimir N. Makarov" <vmakarov at redhat dot com>
- Date: Fri, 11 Feb 2011 13:33:32 +0100
- Subject: Scheduling automaton question
Suppose I have two insns, one reserving (A|B|C), and the other reserving
A. I'm observing that when the first one is scheduled in an otherwise
empty state, it reserves the A unit and blocks the second one from being
scheduled in the same cycle. This is a problem when there's an
anti-dependence of cost 0 between the two instructions.
Vlad - two questions. Is this behaviour what you would expect to happen,
and how much work do you think would be involved to fix it (i.e. make
the first one transition to a state where we can still reserve any two
out of the three units)?
Bernd