Add hook to insert late LLVM=>LLVM passes just before isel

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109354 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index fd10241..98d49ad 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -307,6 +307,8 @@
 
   PM.add(createStackProtectorPass(getTargetLowering()));
 
+  addPreISel(PM, OptLevel);
+
   if (PrintISelInput)
     PM.add(createPrintFunctionPass("\n\n"
                                    "*** Final LLVM Code input to ISel ***\n",