add the branch folding pass as a late cleanup pass for all targets.  For now
it just deletes empty MBB's.  Soon it will do more :)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30941 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index 6c4544a..18ab218 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -63,6 +63,9 @@
   // Insert prolog/epilog code.  Eliminate abstract frame index references...
   PM.add(createPrologEpilogCodeInserter());
   
+  // Branch folding must be run after regalloc and prolog/epilog insertion.
+  PM.add(createBranchFoldingPass());
+  
   if (PrintMachineCode)  // Print the register-allocated code
     PM.add(createMachineFunctionPrinterPass(&std::cerr));