VM: Avoid allocating strings when disassembling code.

runtime/vm/object_service.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/debugger.h"
 #include "vm/disassembler.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/type_table.h"
 
 namespace dart {
 
 #ifndef PRODUCT
 
 static void AddNameProperties(JSONObject* jsobj,
-                              const String& name,
-                              const String& vm_name) {
-  jsobj->AddProperty("name", name.ToCString());
-  if (!name.Equals(vm_name)) {
-    jsobj->AddProperty("_vmName", vm_name.ToCString());
+                              const char* name,
+                              const char* vm_name) {
+  jsobj->AddProperty("name", name);
+  if (strcmp(name, vm_name) != 0) {
+    jsobj->AddProperty("_vmName", vm_name);
   }
 }
 
 
 void Object::AddCommonObjectProperties(JSONObject* jsobj,
                                        const char* protocol_type,
                                        bool ref) const {
   const char* vm_type = JSONType();
   bool same_type = (strcmp(protocol_type, vm_type) == 0);
   if (ref) {
@@ skipping 47 matching lines @@
   JSONObject jsobj(stream);
   if ((raw() == Class::null()) || (id() == kFreeListElement)) {
     // TODO(turnidge): This is weird and needs to be changed.
     jsobj.AddProperty("type", "null");
     return;
   }
   AddCommonObjectProperties(&jsobj, "Class", ref);
   jsobj.AddFixedServiceId("classes/%" Pd "", id());
   const String& scrubbed_name = String::Handle(ScrubbedName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, scrubbed_name, vm_name);
+  AddNameProperties(&jsobj,
+                    scrubbed_name.ToCString(),
+                    vm_name.ToCString());
   if (ref) {
     return;
   }
 
   const Error& err = Error::Handle(EnsureIsFinalized(Thread::Current()));
   if (!err.IsNull()) {
     jsobj.AddProperty("error", err);
   }
   jsobj.AddProperty("abstract", is_abstract());
   jsobj.AddProperty("const", is_const());
@@ skipping 94 matching lines @@
   CanonicalTypeArgumentsSet typeargs_table(
       zone, object_store->canonical_type_arguments());
   const Array& table =
       Array::Handle(HashTables::ToArray(typeargs_table, false));
   typeargs_table.Release();
   ASSERT(table.Length() > 0);
   AddCommonObjectProperties(&jsobj, "TypeArguments", ref);
   jsobj.AddServiceId(*this);
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   if (ref) {
     return;
   }
   {
     JSONArray jsarr(&jsobj, "types");
     AbstractType& type_arg = AbstractType::Handle();
     for (intptr_t i = 0; i < Length(); i++) {
       type_arg = TypeAt(i);
       jsarr.AddValue(type_arg);
     }
@@ skipping 42 matching lines @@
   }
   if (id != -1) {
     ASSERT(selector != NULL);
     jsobj.AddFixedServiceId("classes/%" Pd "/%s/%" Pd "",
                             cls.id(), selector, id);
     return;
   }
   // Regular functions known to their owner use their name (percent-encoded).
   String& name = String::Handle(f.name());
   if (cls.LookupFunction(name) == f.raw()) {
-    name = String::EncodeIRI(name);
+    const char* encoded_name = String::EncodeIRI(name);
     jsobj.AddFixedServiceId("classes/%" Pd "/functions/%s",
-                            cls.id(), name.ToCString());
+                            cls.id(), encoded_name);
     return;
   }
   // Oddball functions (not known to their owner) fall back to use the object
   // id ring. Current known examples are signature functions of closures
   // and stubs like 'megamorphic_miss'.
   jsobj.AddServiceId(f);
 }
 
 
 void Function::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Class& cls = Class::Handle(Owner());
   ASSERT(!cls.IsNull());
   Error& err = Error::Handle();
   err ^= cls.EnsureIsFinalized(Thread::Current());
   ASSERT(err.IsNull());
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Function", ref);
   AddFunctionServiceId(jsobj, *this, cls);
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   const Function& parent = Function::Handle(parent_function());
   if (!parent.IsNull()) {
     jsobj.AddProperty("owner", parent);
   } else if (cls.IsTopLevel()) {
     const Library& library = Library::Handle(cls.library());
     jsobj.AddProperty("owner", library);
   } else {
     jsobj.AddProperty("owner", cls);
   }
 
@@ skipping 43 matching lines @@
 
 void RedirectionData::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Object::PrintJSONImpl(stream, ref);
 }
 
 
 void Field::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   Class& cls = Class::Handle(Owner());
   String& field_name = String::Handle(name());
-  field_name = String::EncodeIRI(field_name);
+  const char* encoded_field_name = String::EncodeIRI(field_name);
   AddCommonObjectProperties(&jsobj, "Field", ref);
   jsobj.AddFixedServiceId("classes/%" Pd "/fields/%s",
-                          cls.id(), field_name.ToCString());
+                          cls.id(), encoded_field_name);
 
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   if (cls.IsTopLevel()) {
     const Library& library = Library::Handle(cls.library());
     jsobj.AddProperty("owner", library);
   } else {
     jsobj.AddProperty("owner", cls);
   }
 
   AbstractType& declared_type = AbstractType::Handle(type());
   jsobj.AddProperty("declaredType", declared_type);
   jsobj.AddProperty("static", is_static());
@@ skipping 54 matching lines @@
   JSONArray members(&jsobj, "members");
 }
 
 
 // See also Dart_ScriptGetTokenInfo.
 void Script::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Script", ref);
   const String& uri = String::Handle(url());
   ASSERT(!uri.IsNull());
-  const String& encoded_uri = String::Handle(String::EncodeIRI(uri));
-  ASSERT(!encoded_uri.IsNull());
+  const char* encoded_uri = String::EncodeIRI(uri);
   const Library& lib = Library::Handle(FindLibrary());
   if (lib.IsNull()) {
     jsobj.AddServiceId(*this);
   } else {
     jsobj.AddFixedServiceId("libraries/%" Pd "/scripts/%s/%" Px64 "",
-                            lib.index(), encoded_uri.ToCString(),
+                            lib.index(), encoded_uri,
                             load_timestamp());
   }
   jsobj.AddPropertyStr("uri", uri);
   jsobj.AddProperty("_kind", GetKindAsCString());
   if (ref) {
     return;
   }
   jsobj.AddPropertyTimeMillis("_loadTime", load_timestamp());
   if (!lib.IsNull()) {
     jsobj.AddProperty("library", lib);
@@ skipping 37 matching lines @@
 
 
 void Library::PrintJSONImpl(JSONStream* stream, bool ref) const {
   intptr_t id = index();
   ASSERT(id >= 0);
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Library", ref);
   jsobj.AddFixedServiceId("libraries/%" Pd "", id);
   const String& vm_name = String::Handle(name());
   const String& scrubbed_name = String::Handle(String::ScrubName(vm_name));
-  AddNameProperties(&jsobj, scrubbed_name, vm_name);
+  AddNameProperties(&jsobj, scrubbed_name.ToCString(), vm_name.ToCString());
   const String& library_url = String::Handle(url());
   jsobj.AddPropertyStr("uri", library_url);
   if (ref) {
     return;
   }
   jsobj.AddProperty("debuggable", IsDebuggable());
   {
     JSONArray jsarr(&jsobj, "classes");
     ClassDictionaryIterator class_iter(*this);
     Class& klass = Class::Handle();
@@ skipping 288 matching lines @@
   }
 }
 
 
 void Code::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Code", ref);
   jsobj.AddFixedServiceId("code/%" Px64"-%" Px "",
                           compile_timestamp(),
                           PayloadStart());
-  const String& qualified_name = String::Handle(QualifiedName());
-  const String& vm_name = String::Handle(Name());
+  const char* qualified_name = QualifiedName();
+  const char* vm_name = Name();
   AddNameProperties(&jsobj, qualified_name, vm_name);
   const bool is_stub = IsStubCode() || IsAllocationStubCode();
   if (is_stub) {
     jsobj.AddProperty("kind", "Stub");
   } else {
     jsobj.AddProperty("kind", "Dart");
   }
   jsobj.AddProperty("_optimized", is_optimized());
   const Object& obj = Object::Handle(owner());
   if (obj.IsFunction()) {
     const Function& func = Function::Cast(obj);
     jsobj.AddProperty("_intrinsic", func.is_intrinsic());
     jsobj.AddProperty("_native", func.is_native());
   } else {
     jsobj.AddProperty("_intrinsic", false);
     jsobj.AddProperty("_native", false);
   }
   if (ref) {
     return;
   }
   if (obj.IsFunction()) {
     jsobj.AddProperty("function", obj);
   } else {
     // Generate a fake function reference.
     JSONObject func(&jsobj, "function");
     func.AddProperty("type", "@Function");
     func.AddProperty("_kind", "Stub");
-    ASSERT(qualified_name.Equals(vm_name));
-    func.AddProperty("name", vm_name.ToCString());
+    ASSERT(strcmp(qualified_name, vm_name) == 0);
+    func.AddProperty("name", vm_name);
     AddNameProperties(&func, vm_name, vm_name);
   }
   jsobj.AddPropertyF("_startAddress", "%" Px "", PayloadStart());
   jsobj.AddPropertyF("_endAddress", "%" Px "", PayloadStart() + Size());
   jsobj.AddProperty("_alive", is_alive());
   const ObjectPool& object_pool = ObjectPool::Handle(GetObjectPool());
   jsobj.AddProperty("_objectPool", object_pool);
   {
     JSONArray jsarr(&jsobj, "_disassembly");
     if (is_alive()) {
@@ skipping 263 matching lines @@
       jsobj.AddFixedServiceId("classes/%" Pd "/types/%d", cid, 0);
     } else {
       jsobj.AddServiceId(*this);
     }
     jsobj.AddProperty("typeClass", type_cls);
   } else {
     jsobj.AddServiceId(*this);
   }
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   if (ref) {
     return;
   }
   const TypeArguments& typeArgs = TypeArguments::Handle(arguments());
   if (!typeArgs.IsNull()) {
     jsobj.AddProperty("typeArguments", typeArgs);
   }
 }
 
 
 void TypeRef::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   PrintSharedInstanceJSON(&jsobj, ref);
   jsobj.AddProperty("kind", "TypeRef");
   jsobj.AddServiceId(*this);
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   if (ref) {
     return;
   }
   jsobj.AddProperty("targetType", AbstractType::Handle(type()));
 }
 
 
 void TypeParameter::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   PrintSharedInstanceJSON(&jsobj, ref);
   jsobj.AddProperty("kind", "TypeParameter");
   jsobj.AddServiceId(*this);
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   const Class& param_cls = Class::Handle(parameterized_class());
   jsobj.AddProperty("parameterizedClass", param_cls);
   if (ref) {
     return;
   }
   jsobj.AddProperty("parameterIndex", index());
   const AbstractType& upper_bound = AbstractType::Handle(bound());
   jsobj.AddProperty("bound", upper_bound);
 }
 
 
 void BoundedType::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   PrintSharedInstanceJSON(&jsobj, ref);
   jsobj.AddProperty("kind", "BoundedType");
   jsobj.AddServiceId(*this);
   const String& user_name = String::Handle(UserVisibleName());
   const String& vm_name = String::Handle(Name());
-  AddNameProperties(&jsobj, user_name, vm_name);
+  AddNameProperties(&jsobj, user_name.ToCString(), vm_name.ToCString());
   if (ref) {
     return;
   }
   jsobj.AddProperty("targetType", AbstractType::Handle(type()));
   jsobj.AddProperty("bound", AbstractType::Handle(bound()));
 }
 
 
 void MixinAppType::PrintJSONImpl(JSONStream* stream, bool ref) const {
   UNREACHABLE();
@@ skipping 382 matching lines @@
   jsobj.AddProperty("mirrorReferent", referent_handle);
 }
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 #endif
 
 }  // namespace dart