Move the loop vectorizer from O2 to O3. It looks like the increase in code size actually hurts the performance on many programs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171471 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/PassManagerBuilder.cpp b/lib/Transforms/IPO/PassManagerBuilder.cpp
index 40bbfb6..e6ee943 100644
--- a/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -187,7 +187,7 @@
   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
   MPM.add(createLoopDeletionPass());          // Delete dead loops
 
-  if (LoopVectorize && OptLevel > 1)
+  if (LoopVectorize && OptLevel > 2)
     MPM.add(createLoopVectorizePass());
 
   if (!DisableUnrollLoops)