[GVNHoist] Re-enable GVNHoist by default

Rebase rL338240 since the excessive memory usage observed when using
GVNHoist with UBSan has been fixed by rL340818.

Differential Revision: https://reviews.llvm.org/D49858

llvm-svn: 340922
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index eb04dcc..a714ac2 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -174,8 +174,8 @@
     cl::desc("Enable the EarlyCSE w/ MemorySSA pass for the new PM (default = on)"));
 
 static cl::opt<bool> EnableGVNHoist(
-    "enable-npm-gvn-hoist", cl::init(false), cl::Hidden,
-    cl::desc("Enable the GVN hoisting pass for the new PM (default = off)"));
+    "enable-npm-gvn-hoist", cl::init(true), cl::Hidden,
+    cl::desc("Enable the GVN hoisting pass for the new PM (default = on)"));
 
 static cl::opt<bool> EnableGVNSink(
     "enable-npm-gvn-sink", cl::init(false), cl::Hidden,