[PATCH] [GVN] Perform Scalar PRE on gep indices that feed loads before doing Load PRE

[Balaram Makam]

All,

I updated my comment with slowdowns in compilation times and other benchmarks that improve with this patch. Slowdowns in compile times are in noise range I do not see any performance regressions greater than 3% in Spec. Based on this data, I would like to get rid of the fast path and will upload a patch removing out the commented-out code if you agree. Thanks for reviewing.

http://reviews.llvm.org/D6103