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

[hfinkel at anl.gov]

Thanks for continuing to work on this!

Generally, please post patches with full context. For instructions on how to do this, see: http://llvm.org/docs/Phabricator.html#requesting-a-review-via-the-web-interface

I think that a 7% speedup sounds nice, does anything else improve? But please do provide some compile-time slowdown numbers, so that we can get a better handle on the cost/benefit analysis.

================
Comment at: lib/Transforms/Scalar/GVN.cpp:2655
@@ -2639,3 +2654,3 @@
   bool Changed = false;
-#if 0
+#if 1
   // Needed for value numbering with phi construction to work.
----------------
If the patch turns this on, please just remove the #if.

http://reviews.llvm.org/D6103