Request for comments on overall approach.

runtime/vm/stub_code_ia32.cc

Index: runtime/vm/stub_code_ia32.cc
diff --git a/runtime/vm/stub_code_ia32.cc b/runtime/vm/stub_code_ia32.cc
index 39cf1a0c0a27496491b236ba2b52b67db6fe3426..b6064a4525f4d79a72a89c2aa933c279fa9decd2 100644
--- a/runtime/vm/stub_code_ia32.cc
+++ b/runtime/vm/stub_code_ia32.cc
@@ -295,7 +295,7 @@ static void MegamorphicLookup(Assembler* assembler) {
   __ j(EQUAL, &null_receiver, Assembler::kNearJump);
   __ testl(EAX, Immediate(kSmiTagMask));
   __ j(ZERO, &smi_receiver, Assembler::kNearJump);
-  __ movl(EAX, FieldAddress(EAX, Object::class_offset()));
+  __ GetClassOf(EAX, EAX, EDI);
   __ jmp(&class_in_eax, Assembler::kNearJump);
   __ Bind(&smi_receiver);
   // For Smis we need to get the class from the isolate.
@@ -673,16 +673,6 @@ void StubCode::GenerateAllocateArrayStub(Assembler* assembler) {
                        FieldAddress(EAX, Array::length_offset()),
                        EDX);
 
-    // EAX: new object start as a tagged pointer.
-    // EBX: new object end address.
-    // EDX: Array length as Smi.
-    // Store class value for array.
-    __ movl(ECX, FieldAddress(CTX, Context::isolate_offset()));
-    __ movl(ECX, Address(ECX, Isolate::object_store_offset()));
-    __ movl(ECX, Address(ECX, ObjectStore::array_class_offset()));
-    __ StoreIntoObject(EAX,
-                       FieldAddress(EAX, Array::class_offset()),
-                       ECX);
     // Calculate the size tag.
     // EAX: new object start as a tagged pointer.
     // EBX: new object end address.
@@ -772,7 +762,7 @@ void StubCode::GenerateCallClosureFunctionStub(Assembler* assembler) {
   __ j(ZERO, &not_closure, Assembler::kNearJump);  // Not a closure, but a smi.
   // Verify that the class of the object is a closure class by checking that
   // class.signature_function() is not null.
-  __ movl(EAX, FieldAddress(EDI, Object::class_offset()));
+  __ GetClassOf(EAX, EDI, ECX);
   __ movl(EAX, FieldAddress(EAX, Class::signature_function_offset()));
   __ cmpl(EAX, raw_null);
   // Actual class is not a closure class.
@@ -1004,13 +994,6 @@ void StubCode::GenerateAllocateContextStub(Assembler* assembler) {
     __ movl(Address::Absolute(heap->TopAddress()), EBX);
     __ addl(EAX, Immediate(kHeapObjectTag));
 
-    // Initialize the class field in the context object.
-    // EAX: new object.
-    // EDX: number of context variables.
-    __ LoadObject(EBX, context_class);  // Load up class field of context.
-    __ StoreIntoObject(EAX,
-                       FieldAddress(EAX, Context::class_offset()),
-                       EBX);
     // Calculate the size tag.
     // EAX: new object.
     // EDX: number of context variables.
@@ -1169,8 +1152,6 @@ void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
               EDX);
       const Class& ita_cls =
           Class::ZoneHandle(Object::instantiated_type_arguments_class());
-      __ LoadObject(EDX, ita_cls);
-      __ movl(Address(ECX, Instance::class_offset()), EDX);  // Set its class.
       // Set the tags.
       uword tags = 0;
       tags = RawObject::SizeTag::update(type_args_size, tags);
@@ -1192,7 +1173,6 @@ void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
     // EBX: next object start.
     // EDI: new object type arguments (if is_cls_parameterized).
     __ LoadObject(EDX, cls);  // Load class of object to be allocated.
-    __ movl(Address(EAX, Instance::class_offset()), EDX);
     // Set the tags.
     uword tags = 0;
     tags = RawObject::SizeTag::update(instance_size, tags);
@@ -1342,11 +1322,8 @@ void StubCode::GenerateAllocationStubForClosure(Assembler* assembler,
     // next object start and initialize the object.
     __ movl(Address::Absolute(heap->TopAddress()), EBX);
 
-    // Initialize the class field in the object.
     // EAX: new closure object.
     // ECX: new context object (only if is_implicit_closure).
-    __ LoadObject(EDX, cls);  // Load signature class of closure.
-    __ movl(Address(EAX, Closure::class_offset()), EDX);
     // Set the tags.
     uword tags = 0;
     tags = RawObject::SizeTag::update(closure_size, tags);
@@ -1371,10 +1348,7 @@ void StubCode::GenerateAllocationStubForClosure(Assembler* assembler,
     } else if (is_implicit_instance_closure) {
       // Initialize the new context capturing the receiver.
 
-      // Set the class field to the Context class.
       const Class& context_class = Class::ZoneHandle(Object::context_class());
-      __ LoadObject(EBX, context_class);
-      __ movl(Address(ECX, Context::class_offset()), EBX);
       // Set the tags.
       uword tags = 0;
       tags = RawObject::SizeTag::update(context_size, tags);
@@ -1576,8 +1550,6 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));  // EAX (argument_count) is Smi.
 
   Label get_class, ic_miss;
-  __ call(&get_class);
-  // EAX: receiver's class
   // ECX: IC data array.
 
 #if defined(DEBUG)
@@ -1601,6 +1573,8 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   // EBX: points directly to the first ic data array element.
   Label loop, found;
   if (num_args == 1) {
+    __ call(&get_class);
+    // EAX: receiver's class
     __ Bind(&loop);
     __ movl(EDI, Address(EBX, 0));  // Get class to check.
     __ cmpl(EAX, EDI);  // Match?
@@ -1613,21 +1587,22 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
     Label no_match;
     __ Bind(&loop);
     // Get class from IC data to check.
-    __ movl(EDI, Address(EBX, 0));
     // Get receiver using argument descriptor in EDX.
     __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
     __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));  // EAX (arg. count) is Smi.
     __ call(&get_class);
+    // TODO(vegorov): is it possible to switch this code to use class ids?
+    __ movl(EDI, Address(EBX, 0));
     __ cmpl(EAX, EDI);  // Match?
     __ j(NOT_EQUAL, &no_match, Assembler::kNearJump);
     // Check second class/argument.
     // Get class from IC data to check.
-    __ movl(EDI, Address(EBX, kWordSize));
     // Get next argument.
     __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
     __ movl(EAX, Address(ESP, EAX, TIMES_2, -kWordSize));
     // EAX (argument count) is Smi.
     __ call(&get_class);
+    __ movl(EDI, Address(EBX, kWordSize));
     __ cmpl(EAX, EDI);  // Match?
     __ j(EQUAL, &found, Assembler::kNearJump);
     __ Bind(&no_match);
@@ -1696,7 +1671,7 @@ void StubCode::GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
   __ ret();
 
   __ Bind(&not_smi);
-  __ movl(EAX, FieldAddress(EAX, Object::class_offset()));
+  __ GetClassOf(EAX, EAX, EDI);
   __ ret();
 }
 
@@ -1802,7 +1777,7 @@ static void GenerateSubtypeNTestCacheStub(Assembler* assembler, int n) {
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   __ movl(EAX, Address(ESP, kInstanceOffsetInBytes));
-  __ movl(ECX, FieldAddress(EAX, Object::class_offset()));
+  __ GetClassOf(ECX, EAX, EBX);
   // EAX: instance, ECX: instance-class.
   // Get instance type arguments
   if (n > 1) {