Request for comments on overall approach.

runtime/vm/stub_code_ia32.cc

 // Copyright (c) 2011, 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/globals.h"
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/assembler_macros.h"
 #include "vm/code_generator.h"
@@ skipping 277 matching lines @@
   // Total number of args is the first Smi in args descriptor array (EDX).
   __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
   __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));  // Get receiver. EAX is a Smi.
   // TODO(srdjan): Remove the special casing below for null receiver, once
   // NullClass is implemented.
   __ cmpl(EAX, raw_null);
   // Use Object class if receiver is null.
   __ 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.
   // Load current Isolate pointer from Context structure into EAX.
   __ movl(EAX, FieldAddress(CTX, Context::isolate_offset()));
   __ movl(EAX, Address(EAX, Isolate::object_store_offset()));
   __ movl(EAX, Address(EAX, ObjectStore::smi_class_offset()));
   __ jmp(&class_in_eax, Assembler::kNearJump);
   __ Bind(&null_receiver);
   __ movl(EAX, FieldAddress(CTX, Context::isolate_offset()));
@@ skipping 357 matching lines @@
     // Store the type argument field.
     __ StoreIntoObject(EAX,
                        FieldAddress(EAX, Array::type_arguments_offset()),
                        ECX);
 
     // Set the length field.
     __ StoreIntoObject(EAX,
                        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.
     // EDX: Array length as Smi.
     {
       Label size_tag_overflow, done;
       __ leal(ECX, Address(EDX, TIMES_2, fixed_size));  // EDX is Smi.
       ASSERT(kSmiTagShift == 1);
       __ andl(ECX, Immediate(-kObjectAlignment));
       __ cmpl(ECX, Immediate(RawObject::SizeTag::kMaxSizeTag));
@@ skipping 69 matching lines @@
 
   // Verify that EDI is a closure by checking its class.
   Label not_closure;
   __ cmpl(EDI, raw_null);
   // Not a closure, but null object.
   __ j(EQUAL, &not_closure, Assembler::kNearJump);
   __ testl(EDI, Immediate(kSmiTagMask));
   __ 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.
   __ j(EQUAL, &not_closure, Assembler::kNearJump);
 
   // EAX is just the signature function. Load the actual closure function.
   __ movl(ECX, FieldAddress(EDI, Closure::function_offset()));
 
   // Load closure context in CTX; note that CTX has already been preserved.
   __ movl(CTX, FieldAddress(EDI, Closure::context_offset()));
@@ skipping 211 matching lines @@
     }
 
     // Successfully allocated the object, now update top to point to
     // next object start and initialize the object.
     // EAX: new object.
     // EBX: next object start.
     // EDX: number of context variables.
     __ 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.
     {
       Label size_tag_overflow, done;
       __ leal(EBX, Address(EDX, TIMES_4, fixed_size));
       __ andl(EBX, Immediate(-kObjectAlignment));
       __ cmpl(EBX, Immediate(RawObject::SizeTag::kMaxSizeTag));
       __ j(ABOVE, &size_tag_overflow, Assembler::kNearJump);
       __ shll(EBX, Immediate(RawObject::kSizeTagBit - kObjectAlignmentLog2));
@@ skipping 138 matching lines @@
       // Initialize InstantiatedTypeArguments object at ECX.
       __ movl(Address(ECX,
           InstantiatedTypeArguments::uninstantiated_type_arguments_offset()),
               EDI);
       __ movl(EDX, Address(ESP, kInstantiatorTypeArgumentsOffset));
       __ movl(Address(ECX,
           InstantiatedTypeArguments::instantiator_type_arguments_offset()),
               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);
       tags = RawObject::ClassTag::update(ita_cls.index(), tags);
       __ movl(Address(ECX, Instance::tags_offset()), Immediate(tags));
       // Set the new InstantiatedTypeArguments object (ECX) as the type
       // arguments (EDI) of the new object (EAX).
       __ movl(EDI, ECX);
       __ addl(EDI, Immediate(kHeapObjectTag));
       // Set EBX to new object end.
       __ movl(EBX, ECX);
       __ Bind(&type_arguments_ready);
       // EAX: new object.
       // EDI: new object type arguments.
     }
 
     // Initialize the class field in the object.
     // EAX: new object start.
     // 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);
     ASSERT(cls.index() != kIllegalObjectKind);
     tags = RawObject::ClassTag::update(cls.index(), tags);
     __ movl(Address(EAX, Instance::tags_offset()), Immediate(tags));
 
     // Initialize the remaining words of the object.
     const Immediate raw_null =
         Immediate(reinterpret_cast<intptr_t>(Object::null()));
@@ skipping 129 matching lines @@
     if (FLAG_use_slow_path) {
       __ jmp(&slow_case);
     } else {
       __ j(ABOVE_EQUAL, &slow_case, Assembler::kNearJump);
     }
 
     // Successfully allocated the object, now update top to point to
     // 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);
     tags = RawObject::ClassTag::update(cls.index(), tags);
     __ movl(Address(EAX, Closure::tags_offset()), Immediate(tags));
 
     // Initialize the function field in the object.
     // EAX: new closure object.
     // ECX: new context object (only if is_implicit_closure).
     // EBX: next object start.
     __ LoadObject(EDX, func);  // Load function of closure to be allocated.
     __ movl(Address(EAX, Closure::function_offset()), EDX);
 
     // Setup the context for this closure.
     if (is_implicit_static_closure) {
       ObjectStore* object_store = Isolate::Current()->object_store();
       ASSERT(object_store != NULL);
       const Context& empty_context =
           Context::ZoneHandle(object_store->empty_context());
       __ LoadObject(EDX, empty_context);
       __ movl(Address(EAX, Closure::context_offset()), EDX);
     } 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);
       tags = RawObject::ClassTag::update(context_class.index(), tags);
       __ movl(Address(ECX, Context::tags_offset()), Immediate(tags));
 
       // Set number of variables field to 1 (for captured receiver).
       __ movl(Address(ECX, Context::num_variables_offset()), Immediate(1));
 
       // Set isolate field to isolate of current context.
@@ skipping 181 matching lines @@
     __ Bind(&not_yet_hot);
   }
 
   ASSERT(num_args > 0);
   // Get receiver (first read number of arguments from argument descriptor array
   // and then access the receiver from the stack).
   __ movl(EAX, FieldAddress(EDX, Array::data_offset()));
   __ 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)
   { Label ok;
     // Check that the IC data array has NumberOfArgumentsChecked() == num_args.
     // 'num_args_tested' is stored as an untagged int.
     __ movl(EBX, FieldAddress(ECX, ICData::num_args_tested_offset()));
     __ cmpl(EBX, Immediate(num_args));
     __ j(EQUAL, &ok, Assembler::kNearJump);
     __ Stop("Incorrect stub for IC data");
     __ Bind(&ok);
   }
 #endif  // DEBUG
 
   // Loop that checks if there is an IC data match.
   // EAX: receiver's class.
   // ECX: IC data object (preserved).
   __ movl(EBX, FieldAddress(ECX, ICData::ic_data_offset()));
   // EBX: ic_data_array with check entries: classes and target functions.
   __ leal(EBX, FieldAddress(EBX, Array::data_offset()));
   // 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?
     __ j(EQUAL, &found, Assembler::kNearJump);
     __ addl(EBX, Immediate(kWordSize * 2));  // Next element (class + target).
     __ cmpl(EDI, raw_null);   // Done?
     __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
   } else if (num_args == 2) {
     // EDI: class to check.
     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);
     // Each test entry has (1 + num_args) array elements.
     __ addl(EBX, Immediate(kWordSize * (1 + num_args)));  // Next element.
     __ cmpl(EDI, raw_null);   // Done?
     __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
   }
 
   __ Bind(&ic_miss);
@@ skipping 48 matching lines @@
   Label not_smi;
   // Test if Smi -> load Smi class for comparison.
   __ testl(EAX, Immediate(kSmiTagMask));
   __ j(NOT_ZERO, &not_smi, Assembler::kNearJump);
   const Class& smi_class =
       Class::ZoneHandle(Isolate::Current()->object_store()->smi_class());
   __ LoadObject(EAX, smi_class);
   __ ret();
 
   __ Bind(&not_smi);
-  __ movl(EAX, FieldAddress(EAX, Object::class_offset()));
+  __ GetClassOf(EAX, EAX, EDI);
   __ ret();
 }
 
 
 // Use inline cache data array to invoke the target or continue in inline
 // cache miss handler. Stub for 1-argument check (receiver class).
 //  ECX: Inline cache data array
 //  EDX: Arguments array
 //  TOS(0): return address
 // Inline cache data array structure:
@@ skipping 85 matching lines @@
 // TOS + 3: SubtypeTestCache.
 // Result in ECX: null -> not found, otherwise result (true or false).
 static void GenerateSubtypeNTestCacheStub(Assembler* assembler, int n) {
   ASSERT((1 <= n) && (n <= 3));
   const intptr_t kInstantiatorTypeArgumentsInBytes = 1 * kWordSize;
   const intptr_t kInstanceOffsetInBytes = 2 * kWordSize;
   const intptr_t kCacheOffsetInBytes = 3 * kWordSize;
   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) {
     // Compute instance type arguments into EBX.
     Label has_no_type_arguments;
     __ movl(EBX, raw_null);
     __ movl(EDI, FieldAddress(ECX,
         Class::type_arguments_instance_field_offset_offset()));
     __ cmpl(EDI, Immediate(Class::kNoTypeArguments));
     __ j(EQUAL, &has_no_type_arguments, Assembler::kNearJump);
@@ skipping 75 matching lines @@
 // TOS + 2: instance.
 // TOS + 3: cache array.
 // Result in ECX: null -> not found, otherwise result (true or false).
 void StubCode::GenerateSubtype3TestCacheStub(Assembler* assembler) {
   GenerateSubtypeNTestCacheStub(assembler, 3);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32