GVN-hoist: enable by default

As we addressed all compilation time problems with GVN-hoist
https://llvm.org/bugs/show_bug.cgi?id=28670
this patch turns GVN-hoist back by default.

Differential Revision: https://reviews.llvm.org/D23136

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277685 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -138,8 +138,8 @@ static cl::opt<int> PreInlineThreshold(
              "(default = 75)"));
 
 static cl::opt<bool> EnableGVNHoist(
-    "enable-gvn-hoist", cl::init(false), cl::Hidden,
-    cl::desc("Enable the experimental GVN Hoisting pass"));
+    "enable-gvn-hoist", cl::init(true), cl::Hidden,
+    cl::desc("Enable the GVN hoisting pass (default = on)"));
 
 PassManagerBuilder::PassManagerBuilder() {
     OptLevel = 2;