[llvm-commits] [llvm] r46227 - /llvm/trunk/include/llvm/ADT/ImmutableSet.h

[Ted Kremenek]

Author: kremenek
Date: Mon Jan 21 16:50:37 2008
New Revision: 46227

URL: http://llvm.org/viewvc/llvm-project?rev=46227&view=rev
Log:
Adjusted ImutAVLTree::ComputeHash to compute a hash value that is based on a
clearer sequence of hashing compositions.

Modified:
    llvm/trunk/include/llvm/ADT/ImmutableSet.h

Modified: llvm/trunk/include/llvm/ADT/ImmutableSet.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/ImmutableSet.h?rev=46227&r1=46226&r2=46227&view=diff

==============================================================================
--- llvm/trunk/include/llvm/ADT/ImmutableSet.h (original)
+++ llvm/trunk/include/llvm/ADT/ImmutableSet.h Mon Jan 21 16:50:37 2008
@@ -210,11 +210,24 @@
   unsigned ComputeHash(ImutAVLTree* L, ImutAVLTree* R, value_type_ref V) {
     FoldingSetNodeID ID;
     
-    ID.AddInteger(L ? L->ComputeHash() : 0);
+    if (L) ID.AddInteger(L->ComputeHash());
     ImutInfo::Profile(ID,V);
-    ID.AddInteger(R ? R->ComputeHash() : 0);
     
-    return ID.ComputeHash();    
+    // Compute the "intermediate" hash.  Basically, we want the net profile to
+    // be:  H(H(....H(H(H(item0),item1),item2)...),itemN), where
+    //  H(item) is the hash of the data item and H(hash,item) is a hash
+    //  of the last item hash and the the next item.
+    
+    unsigned X = ID.ComputeHash();
+    ID.clear();
+    
+    if (R) {
+      ID.AddInteger(X);
+      ID.AddInteger(R->ComputeHash());
+      X = ID.ComputeHash();
+    }
+    
+    return X;
   }
   
   inline unsigned ComputeHash() {