VM: Simplify lowering of is-tests.

runtime/vm/simulator_dbc.cc

 // Copyright (c) 2016, 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 <setjmp.h>  // NOLINT
 #include <stdlib.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_DBC)
 
@@ skipping 2906 matching lines @@
     SP[1] = SP[-0];  // Length.
     SP[2] = SP[-1];  // Type.
     Exit(thread, FP, SP + 3, pc);
     NativeArguments args(thread, 2, SP + 1, SP - 1);
     INVOKE_RUNTIME(DRT_AllocateArray, args);
     SP -= 1;
     DISPATCH();
   }
 
   {
-    BYTECODE(InstanceOf, A);  // Stack: instance, type args, type, cache
+    BYTECODE(InstanceOf, 0);  // Stack: instance, type args, type, cache
     RawInstance* instance = static_cast<RawInstance*>(SP[-3]);
     RawTypeArguments* instantiator_type_arguments =
         static_cast<RawTypeArguments*>(SP[-2]);
     RawAbstractType* type = static_cast<RawAbstractType*>(SP[-1]);
     RawSubtypeTestCache* cache = static_cast<RawSubtypeTestCache*>(SP[0]);
 
     if (cache != null_value) {
       const intptr_t cid = SimulatorHelpers::GetClassId(instance);
 
       RawTypeArguments* instance_type_arguments =
@@ skipping 39 matching lines @@
       SP[3] = instantiator_type_arguments;
       SP[4] = cache;
       Exit(thread, FP, SP + 5, pc);
       NativeArguments native_args(thread, 4, SP + 1, SP - 3);
       INVOKE_RUNTIME(DRT_Instanceof, native_args);
     }
   // clang-format on
 
   InstanceOfOk:
     SP -= 3;
-    if (rA) {  // Negate result.
-      SP[0] = (SP[0] == true_value) ? false_value : true_value;
-    }
     DISPATCH();
   }
 
   {
     BYTECODE(BadTypeError, 0);  // Stack: instance, type args, type, name
     RawObject** args = SP - 3;
     if (args[0] != null_value) {
       SP[1] = args[0];  // instance.
       SP[2] = args[3];  // name.
       SP[3] = args[2];  // type.
@@ skipping 765 matching lines @@
     pc_ = pc;
   }
 
   buf->Longjmp();
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC