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...why movddup is currently defined to take a LHS/RHS: the RHS should always be undef so it should be coded into the movddup def. Another possible syntax would be to add a special kind of shuffle node to give more natural and clean syntax. This is probably the better solution: def movddup : Shuffle4<VR128, undef, 0, 1, 0, 1>, Cost<42>; >> While I agree that we want to refactor this, I really don't think >> that >> we should autogenerate .td files from perl. This has a number of >> significant logistical problems. What is it that perl gives you that...

On Friday 01 May 2009 13:46, Chris Lattner wrote: > Right, a lot of these problems can be solved by some nice refactoring > stuff. I'm also hoping that some of the complexity in defining > shuffle matching code can be helped by making the definition of the > shuffle patterns more declarative within the td file. It would be > really nice to say that "this shuffle does a

...defined to take a LHS/RHS: the RHS should always be undef so > it should be coded into the movddup def. > > Another possible syntax would be to add a special kind of shuffle node > to give more natural and clean syntax. This is probably the better > solution: > > def movddup : Shuffle4<VR128, undef, 0, 1, 0, 1>, Cost<42>; What does "cost" mean here? Currently isel cost means complexity of the matched pattern. It's hard to compute this by hand so the current hack is to allow manual cost adjustments. I think it makes sense for isel to use HW cost (i...