[PATCH] Add a fence elimination pass

[Daniel Berlin]

Wheee.
This brings me back to the world of speculative PRE.

There is a little known paper that makes this actually practical without doing min-cut work.
A person who was at IBM did some work on this.

The paper you want is:
http://link.springer.com/chapter/10.1007%2F11860990_22
A better version is in  David J. Pereira's thesis
See https://dspace.library.uvic.ca/bitstream/handle/1828/292/Pereira_0336403_Thesis-Final_21Dec2007_.pdf?sequence=1&isAllowed=y

This should enable you to do what you want without min-cut, paying a small cost.

I know it's *actually* been implemented in production compilers.

http://reviews.llvm.org/D5758