[Bug tree-optimization/29680] [4.3 Regression] Misscompilation of spec2006 gcc

[dnovillo at redhat dot com]

------- Comment #25 from dnovillo at redhat dot com  2006-11-09 17:38 -------
Subject: Re:  [4.3 Regression] Misscompilation
 of spec2006 gcc

Daniel Berlin wrote on 11/09/06 12:22:

> Right, but the difference is, In the scheme i propose, you'd never
> have overlapping live ranges of vuse/vdefs, and in mem-ssa, you do.
> IE we wouldn't run into all the problems mem-ssa is going to bring in
> this regard.

No, that's not right.  Overlapping live-ranges are not a problem until 
you hit a PHI node.  That's where currently mem-ssa is having 
difficulties with.

We can use those static partitions at key points during SSA renaming. 
Since the partitions are completely unrelated to the renamer, we can 
experiment with different partitioning schemes.  It's actually even 
possible to arrive to a perfect partitioning scheme that doesn't 
introduce false positive dependencies.

More details to follow.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29680