In generated code for ia32 don't load object's class directly from class_ field.

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()));
+  __ LoadClassOfObject(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 456 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()));
+  __ LoadClassOfObject(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 783 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.

[Ivan Posva, 2012/05/30 05:48:09]

This comment is out of date.

   // 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): switch IC data to store class index insted of class.

[Ivan Posva, 2012/05/30 05:48:09]

instead

In general I think resolving this TODO is one of the next major steps.

+    __ 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()));
+  __ LoadClassOfObject(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()));
+  __ LoadClassOfObject(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