[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 4a834b82ba6f7603befe46eed7f1a811cf0d560a..31d7e2e0a81cc905629225a703ee1bd2ca8e3ee2 100644
--- a/src/ic/stub-cache.cc
+++ b/src/ic/stub-cache.cc
@@ -19,33 +19,34 @@ void StubCache::Initialize() {
   Clear();
 }
 
+#ifdef DEBUG
+namespace {
 
-static Code::Flags CommonStubCacheChecks(Name* name, Map* map,
-                                         Code::Flags flags) {
-  flags = Code::RemoveHolderFromFlags(flags);
-
+bool CommonStubCacheChecks(StubCache* stub_cache, Name* name, Map* map,
+                           Code* code) {
   // 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());
-
-  // 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;
+  DCHECK(name->HasHashCode());
+  if (code) {
+    Code::Flags expected_flags = Code::RemoveHolderFromFlags(
+        Code::ComputeHandlerFlags(stub_cache->ic_kind()));
+    Code::Flags flags = Code::RemoveHolderFromFlags(code->flags());
+    DCHECK_EQ(expected_flags, flags);
+    DCHECK_EQ(Code::HANDLER, Code::ExtractKindFromFlags(code->flags()));
+  }
+  return true;
 }
 
+}  // namespace
+#endif
 
 Code* StubCache::Set(Name* name, Map* map, Code* code) {
-  Code::Flags flags = CommonStubCacheChecks(name, map, code->flags());
+  DCHECK(CommonStubCacheChecks(this, name, map, code));
 
   // Compute the primary entry.
-  int primary_offset = PrimaryOffset(name, flags, map);
+  int primary_offset = PrimaryOffset(name, map);
   Entry* primary = entry(primary_, primary_offset);
   Code* old_code = primary->value;
 
@@ -53,9 +54,8 @@ Code* StubCache::Set(Name* name, Map* map, Code* code) {
   // secondary cache before overwriting it.
   if (old_code != isolate_->builtins()->builtin(Builtins::kIllegal)) {
     Map* old_map = primary->map;
-    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);
+    int seed = PrimaryOffset(primary->key, old_map);
+    int secondary_offset = SecondaryOffset(primary->key, seed);
     Entry* secondary = entry(secondary_, secondary_offset);
     *secondary = *primary;
   }
@@ -68,19 +68,16 @@ Code* StubCache::Set(Name* name, Map* map, Code* code) {
   return code;
 }
 
-
-Code* StubCache::Get(Name* name, Map* map, Code::Flags flags) {
-  flags = CommonStubCacheChecks(name, map, flags);
-  int primary_offset = PrimaryOffset(name, flags, map);
+Code* StubCache::Get(Name* name, Map* map) {
+  DCHECK(CommonStubCacheChecks(this, name, map, nullptr));
+  int primary_offset = PrimaryOffset(name, map);
   Entry* primary = entry(primary_, primary_offset);
-  if (primary->key == name && primary->map == map &&
-      flags == Code::RemoveHolderFromFlags(primary->value->flags())) {
+  if (primary->key == name && primary->map == map) {
     return primary->value;
   }
-  int secondary_offset = SecondaryOffset(name, flags, primary_offset);
+  int secondary_offset = SecondaryOffset(name, primary_offset);
   Entry* secondary = entry(secondary_, secondary_offset);
-  if (secondary->key == name && secondary->map == map &&
-      flags == Code::RemoveHolderFromFlags(secondary->value->flags())) {
+  if (secondary->key == name && secondary->map == map) {
     return secondary->value;
   }
   return NULL;
@@ -103,7 +100,6 @@ void StubCache::Clear() {
 
 
 void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
-                                    Code::Flags flags,
                                     Handle<Context> native_context,
                                     Zone* zone) {
   for (int i = 0; i < kPrimaryTableSize; i++) {
@@ -113,7 +109,7 @@ void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
       // with a primitive receiver.
       if (map == NULL) continue;
 
-      int offset = PrimaryOffset(*name, flags, map);
+      int offset = PrimaryOffset(*name, map);
       if (entry(primary_, offset) == &primary_[i] &&
           TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
         types->AddMapIfMissing(Handle<Map>(map), zone);
@@ -129,10 +125,10 @@ void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
       if (map == NULL) continue;
 
       // Lookup in primary table and skip duplicates.
-      int primary_offset = PrimaryOffset(*name, flags, map);
+      int primary_offset = PrimaryOffset(*name, map);
 
       // Lookup in secondary table and add matches.
-      int offset = SecondaryOffset(*name, flags, primary_offset);
+      int offset = SecondaryOffset(*name, primary_offset);
       if (entry(secondary_, offset) == &secondary_[i] &&
           TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
         types->AddMapIfMissing(Handle<Map>(map), zone);