> Let us look at major RTL optimizations: combiner, scheduler, RA. Do > we need a global analysis for building def-use use-def chains? We > don't need it for combiner (only in bb scope),
Combine would work *far better* if it had some uniform data structure. For one thing, that means it could work across blocks, which would be very valuable. For another, there's a tremendous amount of highly-complex code to do the sorts of tracking that is best done with a uniform infrastructure. > we don't need it for scheduler (only for DAG region) Yes, but again, it would work better if it didn't. > we don't need at all for reload. Again, a tremendous amount of kludgery in reload would be removed by having accurate and better-tracked information.
