X64: Changed hash computations to only use lower 32 bits of pointers.

src/stub-cache.h

Index: src/stub-cache.h
diff --git a/src/stub-cache.h b/src/stub-cache.h
index 824f4ff17b923ba8747aeac3297faa279592ff1a..92100ba59875da81610fdac0d2cc28ab0005bb18 100644
--- a/src/stub-cache.h
+++ b/src/stub-cache.h
@@ -203,14 +203,18 @@ class StubCache : public AllStatic {
     // Compute the hash of the name (use entire length field).
     ASSERT(name->HasHashCode());
     uint32_t field = name->length_field();
+    uint32_t map_lowbits =

[Dean McNamee, 2009/05/06 08:29:17]

lowbits makes it sounds differnt than low32, specially since on a 32-bit
platform they're not low, they're the full pointer.

+        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(map));
     // Base the offset on a simple combination of name, flags, and map.
-    uint32_t key = (reinterpret_cast<uint32_t>(map) + field) ^ flags;
+    uint32_t key = (map_lowbits + field) ^ flags;
     return key & ((kPrimaryTableSize - 1) << kHeapObjectTagSize);
   }
 
   static int SecondaryOffset(String* name, Code::Flags flags, int seed) {
     // Use the seed from the primary cache in the secondary cache.
-    uint32_t key = seed - reinterpret_cast<uint32_t>(name) + flags;
+    uint32_t string_lowbits =
+        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name));
+    uint32_t key = seed - string_lowbits + flags;
     return key & ((kSecondaryTableSize - 1) << kHeapObjectTagSize);
   }