[PATCH]: Linear loop transforms

[Daniel Berlin <dberlin at dberlin dot org>]

This does the actual linear loop transform pass.
It is not enabled by default.
When turned on for gcc directory bootstrap, it finds 3 loops to 
interchange (This is not unexpected, since GCC doesn't do much of the type 
of computation it's trying to optimize, and doesn't do it in a nice clean 
way).  It's expect more to help with fortran.

The heuristics are actually not too bad, it's data dependence information 
that stops us from applying interchange to  more loops. Sebastian is 
working on this problem.

I've also tested this pass by forcing it to interchange every loop that it 
thinks is legal to interchange, regardless of whether it made sense to do 
so.

This patch depends on the lambda-code patch, and the tree-data-ref 
cleanups.

Bootstrapped and regtested on powerpc-darwin and i686-pc-linux-gnu.

Attachment: linearloop.diff
Description: Text document