commit 29384efb76a85e84f87c9bf898262d7f1069c38c
author Dan Gohman <gohman@apple.com> Fri Jul 31 18:20:18 2009 +0000
committer Dan Gohman <gohman@apple.com> Fri Jul 31 18:20:18 2009 +0000
tree 31b8ea82dc666e8e68d278ca7cf11062fd40d4b2
parent b4d31306a4f9e84a7ab6ace99964634adb4bf7e6

Teach ValueHandleBase to treat DenseMap's special Empty and Tombstone
values the same way it treats null pointers. This is needed to allow
CallbackVH to be used as a key in a DenseMap.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77695 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/ValueHandle.h

diff --git a/include/llvm/Support/ValueHandle.h b/include/llvm/Support/ValueHandle.h
index e06f2ea..84745ff 100644
--- a/include/llvm/Support/ValueHandle.h
+++ b/include/llvm/Support/ValueHandle.h
@@ -14,6 +14,7 @@
 #ifndef LLVM_SUPPORT_VALUEHANDLE_H
 #define LLVM_SUPPORT_VALUEHANDLE_H
 
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Value.h"
 
@@ -57,32 +58,32 @@
     : PrevPair(0, Kind), Next(0), VP(0) {}
   ValueHandleBase(HandleBaseKind Kind, Value *V)
     : PrevPair(0, Kind), Next(0), VP(V) {
-    if (V)
+    if (isValid(VP))
       AddToUseList();
   }
   ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
     : PrevPair(0, Kind), Next(0), VP(RHS.VP) {
-    if (VP)
+    if (isValid(VP))
       AddToExistingUseList(RHS.getPrevPtr());
   }
   ~ValueHandleBase() {
-    if (VP)
+    if (isValid(VP))
       RemoveFromUseList();   
   }
   
   Value *operator=(Value *RHS) {
     if (VP == RHS) return RHS;
-    if (VP) RemoveFromUseList();
+    if (isValid(VP)) RemoveFromUseList();
     VP = RHS;
-    if (VP) AddToUseList();
+    if (isValid(VP)) AddToUseList();
     return RHS;
   }
 
   Value *operator=(const ValueHandleBase &RHS) {
     if (VP == RHS.VP) return RHS.VP;
-    if (VP) RemoveFromUseList();
+    if (isValid(VP)) RemoveFromUseList();
     VP = RHS.VP;
-    if (VP) AddToExistingUseList(RHS.getPrevPtr());
+    if (isValid(VP)) AddToExistingUseList(RHS.getPrevPtr());
     return VP;
   }
   
@@ -92,6 +93,12 @@
 protected:
   Value *getValPtr() const { return VP; }
 private:
+  static bool isValid(Value *V) {
+    return V &&
+           V != DenseMapInfo<Value *>::getEmptyKey() &&
+           V != DenseMapInfo<Value *>::getTombstoneKey();
+  }
+
   // Callbacks made from Value.
   static void ValueIsDeleted(Value *V);
   static void ValueIsRAUWd(Value *Old, Value *New);