Added TargetPassConfig::setOpt

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150093 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 2877cf1..6d12dd8 100644
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -84,7 +84,10 @@
 TargetPassConfig::~TargetPassConfig() {}
 
 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
-  : ImmutablePass(ID), TM(tm), PM(pm), DisableVerify(false) {
+  : ImmutablePass(ID), TM(tm), PM(pm), Initialized(false),
+    DisableVerify(false),
+    EnableTailMerge(true) {
+
   // Register all target independent codegen passes to activate their PassIDs,
   // including this pass itself.
   initializeCodeGen(*PassRegistry::getPassRegistry());
@@ -103,6 +106,12 @@
   llvm_unreachable("TargetPassConfig should not be constructed on-the-fly");
 }
 
+// Helper to verify the analysis is really immutable.
+void TargetPassConfig::setOpt(bool &Opt, bool Val) {
+  assert(!Initialized && "PassConfig is immutable");
+  Opt = Val;
+}
+
 void TargetPassConfig::addPass(char &ID) {
   // FIXME: check user overrides
   Pass *P = Pass::createPass(ID);