Loop optimizer issues

[Zdenek Dvorak]

Hello,

> Jan> Zdenek is speaking about the invariant motion.  Clearly there are many
> Jan> cases where RTL expansion will bring oppurtunities for invariant motion,
> Jan> so these needs to be re-done on the RTL.
> 
> Jan> Concerning libcalls, they should not exist in post-tree-SSA world as
> Jan> they are just papering over the problem that such complex things should
> Jan> have been moved earlier.
> 
> 	How about starting with a Tree-SSA loop optimization
> infrastructure and then back-filling RTL loop optimizations where they are
> profitable instead of guessing?

how will you judge that without actually trying it?

In this concrete instance there is not much guessing, really.  There
will be some code motion done on tree-ssa as well as on rtl; the only
question is how much will be done where.

Zdenek