Make valgrind happy with SparseSet.

src/hydrogen.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1268 matching lines @@
 }
 
 
 // Simple sparse set with O(1) add, contains, and clear.
 class SparseSet {
  public:
   SparseSet(Zone* zone, int capacity)
       : capacity_(capacity),
         length_(0),
         dense_(zone->NewArray<int>(capacity)),
-        sparse_(zone->NewArray<int>(capacity)) {}
+        sparse_(zone->NewArray<int>(capacity)) {
+#ifndef NVALGRIND
+    // Initialize the sparse array to make valgrind happy.
+    memset(sparse_, 0, sizeof(sparse_[0]) * capacity);
+#endif
+  }
 
   bool Contains(int n) const {
     ASSERT(0 <= n && n < capacity_);
     int d = sparse_[n];
     return 0 <= d && d < length_ && dense_[d] == n;
   }
 
   bool Add(int n) {
     if (Contains(n)) return false;
     dense_[length_] = n;
@@ skipping 5102 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal