1 files changed, 17 insertions, 0 deletions
diff --git a/include/llvm/PassAnalysisSupport.h b/include/llvm/PassAnalysisSupport.h
index b09ba45..f339481 100644
--- a/include/llvm/PassAnalysisSupport.h
+++ b/include/llvm/PassAnalysisSupport.h
@@ -24,6 +24,8 @@
 
 namespace llvm {
 
+class StringRef;
+
 // No need to include Pass.h, we are being included by it!
 
 //===----------------------------------------------------------------------===//
@@ -79,6 +81,9 @@ public:
     return *this;
   }
 
+  // addPreserved - Add the specified Pass class to the set of analyses
+  // preserved by this pass.
+  //
   template<class PassClass>
   AnalysisUsage &addPreserved() {
     assert(Pass::getClassPassInfo<PassClass>() && "Pass class not registered!");
@@ -86,6 +91,18 @@ public:
     return *this;
   }
 
+  // addPreserved - Add the Pass with the specified argument string to the set
+  // of analyses preserved by this pass. If no such Pass exists, do nothing.
+  // This can be useful when a pass is trivially preserved, but may not be
+  // linked in. Be careful about spelling!
+  //
+  AnalysisUsage &addPreserved(const StringRef &Arg) {
+    const PassInfo *PI = Pass::lookupPassInfo(Arg);
+    // If the pass exists, preserve it. Otherwise silently do nothing.
+    if (PI) Preserved.push_back(PI);
+    return *this;
+  }
+
   // setPreservesAll - Set by analyses that do not transform their input at all
   void setPreservesAll() { PreservesAll = true; }
   bool getPreservesAll() const { return PreservesAll; }