Revert of [ic] [stubs] Don't use Code::flags in megamorphic stub cache hash computations.

src/ic/stub-cache.cc

Index: src/ic/stub-cache.cc
diff --git a/src/ic/stub-cache.cc b/src/ic/stub-cache.cc
index 02a8b0ad3403f5e5e030d688e8a3734d191834a5..4a834b82ba6f7603befe46eed7f1a811cf0d560a 100644
--- a/src/ic/stub-cache.cc
+++ b/src/ic/stub-cache.cc
@@ -19,23 +19,33 @@
   Clear();
 }
 
-static void CommonStubCacheChecks(Name* name, Map* map, Code* code) {
+
+static Code::Flags CommonStubCacheChecks(Name* name, Map* map,
+                                         Code::Flags flags) {
+  flags = Code::RemoveHolderFromFlags(flags);
+
   // Validate that the name does not move on scavenge, and that we
   // can use identity checks instead of structural equality checks.
   DCHECK(!name->GetHeap()->InNewSpace(name));
   DCHECK(name->IsUniqueName());
-  DCHECK(name->HasHashCode());
-  if (code) {
-    DCHECK_EQ(Code::HANDLER, Code::ExtractKindFromFlags(code->flags()));
-  }
+
+  // The state bits are not important to the hash function because the stub
+  // cache only contains handlers. Make sure that the bits are the least
+  // significant so they will be the ones masked out.
+  DCHECK_EQ(Code::HANDLER, Code::ExtractKindFromFlags(flags));
+
+  // Make sure that the cache holder are not included in the hash.
+  DCHECK(Code::ExtractCacheHolderFromFlags(flags) == 0);
+
+  return flags;
 }
 
 
 Code* StubCache::Set(Name* name, Map* map, Code* code) {
-  CommonStubCacheChecks(name, map, code);
+  Code::Flags flags = CommonStubCacheChecks(name, map, code->flags());
 
   // Compute the primary entry.
-  int primary_offset = PrimaryOffset(name, map);
+  int primary_offset = PrimaryOffset(name, flags, map);
   Entry* primary = entry(primary_, primary_offset);
   Code* old_code = primary->value;
 
@@ -43,8 +53,9 @@
   // secondary cache before overwriting it.
   if (old_code != isolate_->builtins()->builtin(Builtins::kIllegal)) {
     Map* old_map = primary->map;
-    int seed = PrimaryOffset(primary->key, old_map);
-    int secondary_offset = SecondaryOffset(primary->key, seed);
+    Code::Flags old_flags = Code::RemoveHolderFromFlags(old_code->flags());
+    int seed = PrimaryOffset(primary->key, old_flags, old_map);
+    int secondary_offset = SecondaryOffset(primary->key, old_flags, seed);
     Entry* secondary = entry(secondary_, secondary_offset);
     *secondary = *primary;
   }
@@ -57,16 +68,19 @@
   return code;
 }
 
-Code* StubCache::Get(Name* name, Map* map) {
-  CommonStubCacheChecks(name, map, nullptr);
-  int primary_offset = PrimaryOffset(name, map);
+
+Code* StubCache::Get(Name* name, Map* map, Code::Flags flags) {
+  flags = CommonStubCacheChecks(name, map, flags);
+  int primary_offset = PrimaryOffset(name, flags, map);
   Entry* primary = entry(primary_, primary_offset);
-  if (primary->key == name && primary->map == map) {
+  if (primary->key == name && primary->map == map &&
+      flags == Code::RemoveHolderFromFlags(primary->value->flags())) {
     return primary->value;
   }
-  int secondary_offset = SecondaryOffset(name, primary_offset);
+  int secondary_offset = SecondaryOffset(name, flags, primary_offset);
   Entry* secondary = entry(secondary_, secondary_offset);
-  if (secondary->key == name && secondary->map == map) {
+  if (secondary->key == name && secondary->map == map &&
+      flags == Code::RemoveHolderFromFlags(secondary->value->flags())) {
     return secondary->value;
   }
   return NULL;
@@ -89,6 +103,7 @@
 
 
 void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
+                                    Code::Flags flags,
                                     Handle<Context> native_context,
                                     Zone* zone) {
   for (int i = 0; i < kPrimaryTableSize; i++) {
@@ -98,7 +113,7 @@
       // with a primitive receiver.
       if (map == NULL) continue;
 
-      int offset = PrimaryOffset(*name, map);
+      int offset = PrimaryOffset(*name, flags, map);
       if (entry(primary_, offset) == &primary_[i] &&
           TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
         types->AddMapIfMissing(Handle<Map>(map), zone);
@@ -114,10 +129,10 @@
       if (map == NULL) continue;
 
       // Lookup in primary table and skip duplicates.
-      int primary_offset = PrimaryOffset(*name, map);
+      int primary_offset = PrimaryOffset(*name, flags, map);
 
       // Lookup in secondary table and add matches.
-      int offset = SecondaryOffset(*name, primary_offset);
+      int offset = SecondaryOffset(*name, flags, primary_offset);
       if (entry(secondary_, offset) == &secondary_[i] &&
           TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
         types->AddMapIfMissing(Handle<Map>(map), zone);