VM: Better code for is-checks and checked mode checks with simple types

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2013, 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"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 369 matching lines @@
   if (smi_class.IsSubtypeOf(TypeArguments::Handle(zone()),
                             type_class,
                             TypeArguments::Handle(zone()),
                             NULL,
                             NULL,
                             Heap::kOld)) {
     __ j(ZERO, is_instance_lbl);
   } else {
     __ j(ZERO, is_not_instance_lbl);
   }
-  // Compare if the classes are equal.
   const Register kClassIdReg = R10;
   __ LoadClassId(kClassIdReg, kInstanceReg);
-  __ cmpl(kClassIdReg, Immediate(type_class.id()));
-  __ j(EQUAL, is_instance_lbl);
   // See ClassFinalizer::ResolveSuperTypeAndInterfaces for list of restricted
   // interfaces.
   // Bool interface can be implemented only by core class Bool.
   if (type.IsBoolType()) {
     __ cmpl(kClassIdReg, Immediate(kBoolCid));
     __ j(EQUAL, is_instance_lbl);
     __ jmp(is_not_instance_lbl);
     return false;
   }
-  if (type.IsDartFunctionType()) {
-    // Check if instance is a closure.
-    __ cmpq(kClassIdReg, Immediate(kClosureCid));
-    __ j(EQUAL, is_instance_lbl);
-  }
   // Custom checking for numbers (Smi, Mint, Bigint and Double).
   // Note that instance is not Smi (checked above).
   if (type.IsSubtypeOf(
       Type::Handle(zone(), Type::Number()), NULL, NULL, Heap::kOld)) {
     GenerateNumberTypeCheck(
         kClassIdReg, type, is_instance_lbl, is_not_instance_lbl);
     return false;
   }
   if (type.IsStringType()) {
     GenerateStringTypeCheck(kClassIdReg, is_instance_lbl, is_not_instance_lbl);
     return false;
   }
+  if (type.IsDartFunctionType()) {
+    // Check if instance is a closure.
+    __ cmpq(kClassIdReg, Immediate(kClosureCid));
+    __ j(EQUAL, is_instance_lbl);
+    return true;
+  }
+  // Compare if the classes are equal.
+  if (!type_class.is_abstract()) {
+    __ cmpl(kClassIdReg, Immediate(type_class.id()));
+    __ j(EQUAL, is_instance_lbl);
+  }
   // Otherwise fallthrough.
   return true;
 }
 
 
 // Uses SubtypeTestCache to store instance class and result.
 // RAX: instance to test.
 // Clobbers R10, R13.
 // Immediate class test already done.
 // TODO(srdjan): Implement a quicker subtype check, as type test
@@ skipping 1431 matching lines @@
   __ movups(reg, Address(RSP, 0));
   __ AddImmediate(RSP, Immediate(kFpuRegisterSize));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64