Revert "VM: Simplify lowering of is-tests."

runtime/vm/flow_graph_compiler_mips.cc

Index: runtime/vm/flow_graph_compiler_mips.cc
diff --git a/runtime/vm/flow_graph_compiler_mips.cc b/runtime/vm/flow_graph_compiler_mips.cc
index bc76e97a394b6d3378b0041a5555c4a9b9612458..88998fe385de42e62c8981584338680271d8a626 100644
--- a/runtime/vm/flow_graph_compiler_mips.cc
+++ b/runtime/vm/flow_graph_compiler_mips.cc
@@ -544,6 +544,7 @@ RawSubtypeTestCache* FlowGraphCompiler::GenerateInlineInstanceof(
 void FlowGraphCompiler::GenerateInstanceOf(TokenPosition token_pos,
                                            intptr_t deopt_id,
                                            const AbstractType& type,
+                                           bool negate_result,
                                            LocationSummary* locs) {
   ASSERT(type.IsFinalized() && !type.IsMalformed() && !type.IsMalbounded());
   ASSERT(!type.IsObjectType() && !type.IsDynamicType());
@@ -593,15 +594,21 @@ void FlowGraphCompiler::GenerateInstanceOf(TokenPosition token_pos,
     // instanceof runtime call will be left as the result of the operation.
     __ lw(T0, Address(SP, 4 * kWordSize));
     __ addiu(SP, SP, Immediate(5 * kWordSize));
-    __ mov(V0, T0);
+    if (negate_result) {
+      __ LoadObject(V0, Bool::True());
+      __ bne(T0, V0, &done);
+      __ LoadObject(V0, Bool::False());
+    } else {
+      __ mov(V0, T0);
+    }
     __ b(&done);
   }
   __ Bind(&is_not_instance);
-  __ LoadObject(V0, Bool::Get(false));
+  __ LoadObject(V0, Bool::Get(negate_result));
   __ b(&done);
 
   __ Bind(&is_instance);
-  __ LoadObject(V0, Bool::Get(true));
+  __ LoadObject(V0, Bool::Get(!negate_result));
   __ Bind(&done);
   // Remove instantiator type arguments (A1).
   __ Drop(1);