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Re: Combine four insns


On 08/06/10 14:43, Steven Bosscher wrote:

If it's patterns we could combine at the GIMPLE level, it wouldn't be so silly to handle it there. Weren't you once one of the people talking about a tree-combine pass?
The specific cases I've seen won't combine at the gimple level. For example, if you look at the H8, you need to have a post-inc memory operand which I really doubt we're going to ever expose at the gimple level.

I still think a tree combiner would be a great thing to have as it would eliminate tree-ssa-forwprop with a more generic engine.

Or if this is a case the compiler could already expand from GIMPLE to
good initial RTL (i.e. TER), that wouldn't be a silly place to put it
either.
Again, I don't think the majority of the cases where 4->1 or 4->2 combinations occur are going to be anything that we'd expose that early in the pipeline.

Jeff


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