Factor FlattenCFG out from SimplifyCFG

Patch by: Mei Ye

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187764 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/lto/LTOCodeGenerator.cpp b/tools/lto/LTOCodeGenerator.cpp
index 776a5b9..6139ade 100644
--- a/tools/lto/LTOCodeGenerator.cpp
+++ b/tools/lto/LTOCodeGenerator.cpp
@@ -118,7 +118,7 @@
   initializeGVNPass(R);
   initializeMemCpyOptPass(R);
   initializeDCEPass(R);
-  initializeCFGCanonicalizePass(R);
+  initializeCFGSimplifyPassPass(R);
 }
 
 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {