[serializer] cache ICs only as code stubs with key.

Some uninitialized ICs used to be implemented as builtins. This is apparently
no longer the case.

R=bmeurer@chromium.org, mvstanton@chromium.org

Review-Url: https://codereview.chromium.org/1940283002
Cr-Commit-Position: refs/heads/master@{#35980}

src/snapshot/code-serializer.cc

@@ -73,12 +73,10 @@ void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
                          where_to_point);
         return;
       case Code::STUB:
-        SerializeCodeStub(code_object->stub_key(), how_to_code, where_to_point);
-        return;
 #define IC_KIND_CASE(KIND) case Code::KIND:
         IC_KIND_LIST(IC_KIND_CASE)
 #undef IC_KIND_CASE
-        SerializeIC(code_object, how_to_code, where_to_point);
+        SerializeCodeStub(code_object->stub_key(), how_to_code, where_to_point);
         return;
       case Code::FUNCTION:
         DCHECK(code_object->has_reloc_info_for_serialization());
@@ -149,37 +147,6 @@ void CodeSerializer::SerializeCodeStub(uint32_t stub_key, HowToCode how_to_code,
   sink_->PutInt(index, "CodeStub key");
 }
 
-void CodeSerializer::SerializeIC(Code* ic, HowToCode how_to_code,
-                                 WhereToPoint where_to_point) {
-  // The IC may be implemented as a stub.
-  uint32_t stub_key = ic->stub_key();
-  if (stub_key != CodeStub::NoCacheKey()) {
-    if (FLAG_trace_serializer) {
-      PrintF(" %s is a code stub\n", Code::Kind2String(ic->kind()));
-    }
-    SerializeCodeStub(stub_key, how_to_code, where_to_point);
-    return;
-  }
-  // The IC may be implemented as builtin. Only real builtins have an
-  // actual builtin_index value attached (otherwise it's just garbage).
-  // Compare to make sure we are really dealing with a builtin.
-  int builtin_index = ic->builtin_index();
-  if (builtin_index < Builtins::builtin_count) {
-    Builtins::Name name = static_cast<Builtins::Name>(builtin_index);
-    Code* builtin = isolate()->builtins()->builtin(name);
-    if (builtin == ic) {
-      if (FLAG_trace_serializer) {
-        PrintF(" %s is a builtin\n", Code::Kind2String(ic->kind()));
-      }
-      DCHECK(ic->kind() == Code::KEYED_LOAD_IC ||
-             ic->kind() == Code::KEYED_STORE_IC);
-      SerializeBuiltin(builtin_index, how_to_code, where_to_point);
-      return;
-    }
-  }
-  UNREACHABLE();
-}
-
 int CodeSerializer::AddCodeStubKey(uint32_t stub_key) {
   // TODO(yangguo) Maybe we need a hash table for a faster lookup than O(n^2).
   int index = 0;

src/snapshot/code-serializer.h

@@ -45,8 +45,6 @@ class CodeSerializer : public Serializer {
 
   void SerializeBuiltin(int builtin_index, HowToCode how_to_code,
                         WhereToPoint where_to_point);
-  void SerializeIC(Code* ic, HowToCode how_to_code,
-                   WhereToPoint where_to_point);
   void SerializeCodeStub(uint32_t stub_key, HowToCode how_to_code,
                          WhereToPoint where_to_point);
   void SerializeGeneric(HeapObject* heap_object, HowToCode how_to_code,