Add an empty key for DebugLoc so that you can store an empty DebugLoc in a

DenseMap.

llvm-svn: 128994

llvm/include/llvm/Support/DebugLoc.h

@@ -27,14 +27,22 @@ namespace llvm {
   class DebugLoc {
     friend struct DenseMapInfo<DebugLoc>;
 
-    /// getTombstoneKey() - A private constructor that returns an unknown that
-    /// is distinguishable from the usual one.
-    static DebugLoc getTombstoneKey() {
+    /// getEmptyKey() - A private constructor that returns an unknown that is
+    /// not equal to the tombstone key or DebugLoc().
+    static DebugLoc getEmptyKey() {
       DebugLoc DL;
       DL.LineCol = -1;
       return DL;
     }
 
+    /// getTombstoneKey() - A private constructor that returns an unknown that
+    /// is not equal to the empty key or DebugLoc().
+    static DebugLoc getTombstoneKey() {
+      DebugLoc DL;
+      DL.LineCol = -2;
+      return DL;
+    }
+
     /// LineCol - This 32-bit value encodes the line and column number for the
     /// location, encoded as 24-bits for line and 8 bits for col.  A value of 0
     /// for either means unknown.

llvm/lib/VMCore/DebugLoc.cpp

@@ -133,7 +133,7 @@ DebugLoc DebugLoc::getFromDILocation(MDNode *N) {
 //===----------------------------------------------------------------------===//
 
 DebugLoc DenseMapInfo<DebugLoc>::getEmptyKey() {
-  return DebugLoc();
+  return DebugLoc::getEmptyKey();
 }
 
 DebugLoc DenseMapInfo<DebugLoc>::getTombstoneKey() {