Register interlocks

[Paul Brook]

> Are there any targets with register interlock where
> gcc handles moving instructions between conflicting
> instructions?
>
> Any suggestions on how this might be represented
> in .md files?  It doesn't seem that the pipeline
> description would seem appropriate.

This is approximately what ia64 has with bundling.
I don't know the exact details, but I believe it has has a md-reorg pass that 
uses scheduler hooks.

Paul