Use SaveAndRestore to simplify logic in LiveVariables::runOnAllBlocks(). Patch by Kovarththanan Rajaratnam!

llvm-svn: 86343

2 files changed, 6 insertions, 3 deletions

diff --git a/clang/include/clang/Analysis/Support/SaveAndRestore.h b/clang/include/clang/Analysis/Support/SaveAndRestore.h
index 4720c22d990..f720639490d 100644
--- a/clang/include/clang/Analysis/Support/SaveAndRestore.h
+++ b/clang/include/clang/Analysis/Support/SaveAndRestore.h
@@ -22,6 +22,9 @@ namespace clang {
 template<typename T>
 struct SaveAndRestore {
   SaveAndRestore(T& x) : X(x), old_value(x) {}
+  SaveAndRestore(T& x, const T &new_value) : X(x), old_value(x) {
+    X = new_value;
+  }
   ~SaveAndRestore() { X = old_value; }
   T get() { return old_value; }
 private:
diff --git a/clang/lib/Analysis/LiveVariables.cpp b/clang/lib/Analysis/LiveVariables.cpp
index df7e48dfd4a..070481fa146 100644
--- a/clang/lib/Analysis/LiveVariables.cpp
+++ b/clang/lib/Analysis/LiveVariables.cpp
@@ -18,6 +18,7 @@
 #include "clang/Analysis/CFG.h"
 #include "clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h"
 #include "clang/Analysis/FlowSensitive/DataflowSolver.h"
+#include "clang/Analysis/Support/SaveAndRestore.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Compiler.h"
@@ -301,10 +302,9 @@ void LiveVariables::runOnAllBlocks(const CFG& cfg,
                                    LiveVariables::ObserverTy* Obs,
                                    bool recordStmtValues) {
   Solver S(*this);
-  ObserverTy* OldObserver = getAnalysisData().Observer;
-  getAnalysisData().Observer = Obs;
+  SaveAndRestore<LiveVariables::ObserverTy*> SRObs(getAnalysisData().Observer,
+                                                   Obs);
   S.runOnAllBlocks(cfg, recordStmtValues);
-  getAnalysisData().Observer = OldObserver;
 }
 
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