Fix secondary stub cache and add a test for the stub cache lookups.

src/stub-cache.h

Index: src/stub-cache.h
===================================================================
--- src/stub-cache.h	(revision 10860)
+++ src/stub-cache.h	(working copy)
@@ -69,6 +69,7 @@
   struct Entry {
     String* key;
     Code* value;
+    Map* map;
   };
 
   void Initialize(bool create_heap_objects);
@@ -252,7 +253,7 @@
                            Handle<Context> global_context);
 
   // Generate code for probing the stub cache table.
-  // Arguments extra and extra2 may be used to pass additional scratch
+  // Arguments extra, extra2 and extra3 may be used to pass additional scratch
   // registers. Set to no_reg if not needed.
   void GenerateProbe(MacroAssembler* masm,
                      Code::Flags flags,
@@ -260,7 +261,8 @@
                      Register name,
                      Register scratch,
                      Register extra,
-                     Register extra2 = no_reg);
+                     Register extra2 = no_reg,
+                     Register extra3 = no_reg);
 
   enum Table {
     kPrimary,
@@ -274,6 +276,12 @@
   }
 
 
+  SCTableReference map_reference(StubCache::Table table) {
+    return SCTableReference(
+        reinterpret_cast<Address>(&first_entry(table)->map));
+  }
+
+
   SCTableReference value_reference(StubCache::Table table) {
     return SCTableReference(
         reinterpret_cast<Address>(&first_entry(table)->value));
@@ -328,19 +336,23 @@
     // Use the seed from the primary cache in the secondary cache.
     uint32_t string_low32bits =
         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name));
-    uint32_t key = seed - string_low32bits + flags;
+    // We always set the in_loop bit to zero when generating the lookup code
+    // so do it here too so the hash codes match.
+    uint32_t iflags =
+        (static_cast<uint32_t>(flags) & ~Code::kFlagsNotUsedInLookup);
+    uint32_t key = (seed - string_low32bits) + iflags;
     return key & ((kSecondaryTableSize - 1) << kHeapObjectTagSize);
   }
 
   // Compute the entry for a given offset in exactly the same way as
   // we do in generated code.  We generate an hash code that already
-  // ends in String::kHashShift 0s.  Then we shift it so it is a multiple
+  // ends in String::kHashShift 0s.  Then we multiply it so it is a multiple
   // of sizeof(Entry).  This makes it easier to avoid making mistakes
   // in the hashed offset computations.
   static Entry* entry(Entry* table, int offset) {
-    const int shift_amount = kPointerSizeLog2 + 1 - String::kHashShift;
+    const int multiplier = sizeof(*table) >> String::kHashShift;
     return reinterpret_cast<Entry*>(
-        reinterpret_cast<Address>(table) + (offset << shift_amount));
+        reinterpret_cast<Address>(table) + offset * multiplier);
   }
 
   static const int kPrimaryTableBits = 11;