In generated code for x64 don't load object's class directly from class_ field.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2012, 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_X64)
 
 #include "vm/assembler.h"
 #include "vm/assembler_macros.h"
 #include "vm/code_generator.h"
@@ skipping 276 matching lines @@
   // Total number of args is the first Smi in args descriptor array (R10).
   __ movq(RAX, FieldAddress(R10, Array::data_offset()));
   __ movq(RAX, Address(RSP, RAX, TIMES_4, 0));  // Get receiver. RAX is a Smi.
   // TODO(srdjan): Remove the special casing below for null receiver, once
   // NullClass is implemented.
   __ cmpq(RAX, raw_null);
   // Use Object class if receiver is null.
   __ j(EQUAL, &null_receiver, Assembler::kNearJump);
   __ testq(RAX, Immediate(kSmiTagMask));
   __ j(ZERO, &smi_receiver, Assembler::kNearJump);
-  __ movq(RAX, FieldAddress(RAX, Object::class_offset()));
+  __ LoadClassOfObject(RAX, RAX);
   __ jmp(&class_in_rax, Assembler::kNearJump);
   __ Bind(&smi_receiver);
   // For Smis we need to get the class from the isolate.
   // Load current Isolate pointer from Context structure into RAX.
   __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
   __ movq(RAX, Address(RAX, Isolate::object_store_offset()));
   __ movq(RAX, Address(RAX, ObjectStore::smi_class_offset()));
   __ jmp(&class_in_rax, Assembler::kNearJump);
   __ Bind(&null_receiver);
   __ movq(RAX, FieldAddress(CTX, Context::isolate_offset()));
@@ skipping 434 matching lines @@
 
   // Total number of args is the first Smi in args descriptor array (R10).
   __ movq(RAX, FieldAddress(R10, Array::data_offset()));  // Load num_args.
   // Load closure object in R13.
   __ movq(R13, Address(RSP, RAX, TIMES_4, kWordSize));  // RAX is a Smi.
 
   // Verify that R13 is a closure by checking its class.
   Label not_closure;
   __ cmpq(R13, raw_null);
   // Not a closure, but null object.
-  __ j(EQUAL, &not_closure, Assembler::kNearJump);
+  __ j(EQUAL, &not_closure);
   __ testq(R13, Immediate(kSmiTagMask));
-  __ j(ZERO, &not_closure, Assembler::kNearJump);  // Not a closure, but a smi.
+  __ j(ZERO, &not_closure);  // 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.
-  __ movq(RAX, FieldAddress(R13, Object::class_offset()));
+  __ LoadClassOfObject(RAX, R13);
   __ movq(RAX, FieldAddress(RAX, Class::signature_function_offset()));
   __ cmpq(RAX, raw_null);
   // Actual class is not a closure class.
   __ j(EQUAL, &not_closure, Assembler::kNearJump);
 
   // RAX is just the signature function. Load the actual closure function.
   __ movq(RBX, FieldAddress(R13, Closure::function_offset()));
 
   // Load closure context in CTX; note that CTX has already been preserved.
   __ movq(CTX, FieldAddress(R13, Closure::context_offset()));
@@ skipping 779 matching lines @@
     __ LeaveFrame();
     __ 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).
   __ movq(RAX, FieldAddress(R10, Array::data_offset()));
   __ movq(RAX, Address(RSP, RAX, TIMES_4, 0));  // RAX (argument count) is Smi.
 
   Label get_class, ic_miss;
-  __ call(&get_class);
-  // RAX: receiver's class
   // RBX: 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.
     __ movq(RCX, FieldAddress(RBX, ICData::num_args_tested_offset()));
     __ cmpq(RCX, 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.
-  // RAX: receiver's class.
   // RBX: IC data object (preserved).
   __ movq(R12, FieldAddress(RBX, ICData::ic_data_offset()));
   // R12: ic_data_array with check entries: classes and target functions.
   __ leaq(R12, FieldAddress(R12, Array::data_offset()));
   // R12: points directly to the first ic data array element.
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   Label loop, found;
   if (num_args == 1) {
+    __ call(&get_class);
+    // RAX: receiver's class.
     __ Bind(&loop);
     __ movq(R13, Address(R12, 0));  // Get class to check.
     __ cmpq(RAX, R13);  // Match?
     __ j(EQUAL, &found, Assembler::kNearJump);
     __ addq(R12, Immediate(kWordSize * 2));  // Next element (class + target).
     __ cmpq(R13, raw_null);   // Done?
     __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
   } else if (num_args == 2) {
     Label no_match;
     __ Bind(&loop);
-    __ movq(R13, Address(R12, 0));  // Get class from IC data to check.
     // Get receiver.
     __ movq(RAX, FieldAddress(R10, Array::data_offset()));
     __ movq(RAX, Address(RSP, RAX, TIMES_4, 0));  // RAX is Smi.
     __ call(&get_class);
+    // TODO(vegorov): switch IC data to store class index instead of class.
+    __ movq(R13, Address(R12, 0));  // Get class from IC data to check.
     __ cmpq(RAX, R13);  // Match?
     __ j(NOT_EQUAL, &no_match, Assembler::kNearJump);
     // Check second.
-    __ movq(R13, Address(R12, kWordSize));  // Get class from IC data to check.
     // Get next argument.
     __ movq(RAX, FieldAddress(R10, Array::data_offset()));
     __ movq(RAX, Address(RSP, RAX, TIMES_4, -kWordSize));  // RAX is Smi.
     __ call(&get_class);
+    __ movq(R13, Address(R12, kWordSize));  // Get class from IC data to check.
     __ cmpq(RAX, R13);  // Match?
     __ j(EQUAL, &found);
     __ Bind(&no_match);
     __ addq(R12, Immediate(kWordSize * (1 + num_args)));  // Next element.
     __ cmpq(R13, raw_null);   // Done?
     __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
   }
 
   __ Bind(&ic_miss);
   // Compute address of arguments (first read number of arguments from argument
@@ skipping 45 matching lines @@
   Label not_smi;
   // Test if Smi -> load Smi class for comparison.
   __ testq(RAX, Immediate(kSmiTagMask));
   __ j(NOT_ZERO, &not_smi, Assembler::kNearJump);
   const Class& smi_class =
       Class::ZoneHandle(Isolate::Current()->object_store()->smi_class());
   __ LoadObject(RAX, smi_class);
   __ ret();
 
   __ Bind(&not_smi);
-  __ movq(RAX, FieldAddress(RAX, Object::class_offset()));
+  __ LoadClassOfObject(RAX, RAX);
   __ ret();
 }
 
 
 // Use inline cache data array to invoke the target or continue in inline
 // cache miss handler. Stub for 1-argument check (receiver class).
 //  RCX: Inline cache data array
 //  RDX: Arguments array
 //  TOS(0): return address
 // Inline cache data array structure:
@@ skipping 77 matching lines @@
 // TOS + 3: SubtypeTestCache.
 // Result in RCX: null -> not found, otherwise result (true or false).
 static void GenerateSubtypeNTestCacheStub(Assembler* assembler, int n) {
   ASSERT((1 <= n) && (n <= 3));
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   const intptr_t kInstantiatorTypeArgumentsInBytes = 1 * kWordSize;
   const intptr_t kInstanceOffsetInBytes = 2 * kWordSize;
   const intptr_t kCacheOffsetInBytes = 3 * kWordSize;
   __ movq(RAX, Address(RSP, kInstanceOffsetInBytes));
-  __ movq(R10, FieldAddress(RAX, Object::class_offset()));
+  __ LoadClassOfObject(R10, RAX);
   // RAX: instance, R10: instance class.
   if (n > 1) {
     // Compute instance type arguments into R13.
     Label has_no_type_arguments;
     __ movq(R13, raw_null);
     __ movq(RDI, FieldAddress(R10,
         Class::type_arguments_instance_field_offset_offset()));
     __ cmpq(RDI, Immediate(Class::kNoTypeArguments));
     __ j(EQUAL, &has_no_type_arguments, Assembler::kNearJump);
     __ movq(R13, FieldAddress(RAX, RDI, TIMES_1, 0));
@@ skipping 74 matching lines @@
 // TOS + 2: instance.
 // TOS + 3: cache array.
 // Result in RCX: null -> not found, otherwise result (true or false).
 void StubCode::GenerateSubtype3TestCacheStub(Assembler* assembler) {
   GenerateSubtypeNTestCacheStub(assembler, 3);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64