Identify Analysis pass.
Do not run analysis pass again if analysis info is still available.
This fixes PR1441.

llvm-svn: 48476
diff --git a/llvm/lib/Analysis/LoadValueNumbering.cpp b/llvm/lib/Analysis/LoadValueNumbering.cpp
index 0a2f36b..6dd55a4 100644
--- a/llvm/lib/Analysis/LoadValueNumbering.cpp
+++ b/llvm/lib/Analysis/LoadValueNumbering.cpp
@@ -43,6 +43,9 @@
     static char ID; // Class identification, replacement for typeinfo
     LoadVN() : FunctionPass((intptr_t)&ID) {}
 
+    /// isAnalysis - Return true if this pass is  implementing an analysis pass.
+    virtual bool isAnalysis() const { return true; }
+
     /// Pass Implementation stuff.  This doesn't do any analysis.
     ///
     bool runOnFunction(Function &) { return false; }