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

runtime/vm/flow_graph_compiler_ia32.cc

Index: runtime/vm/flow_graph_compiler_ia32.cc
diff --git a/runtime/vm/flow_graph_compiler_ia32.cc b/runtime/vm/flow_graph_compiler_ia32.cc
index 86cfb8cc4276c4ab7c7ff056fbec7a9ef8399429..88d95b9268e71d34bb778d850afe17f929bf173a 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -561,6 +561,7 @@ 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.IsMalformedOrMalbounded());
   ASSERT(!type.IsObjectType() && !type.IsDynamicType());
@@ -603,15 +604,23 @@ void FlowGraphCompiler::GenerateInstanceOf(TokenPosition token_pos,
     // Pop the parameters supplied to the runtime entry. The result of the
     // instanceof runtime call will be left as the result of the operation.
     __ Drop(4);
-    __ popl(EAX);
+    if (negate_result) {
+      __ popl(EDX);
+      __ LoadObject(EAX, Bool::True());
+      __ cmpl(EDX, EAX);
+      __ j(NOT_EQUAL, &done, Assembler::kNearJump);
+      __ LoadObject(EAX, Bool::False());
+    } else {
+      __ popl(EAX);
+    }
     __ jmp(&done, Assembler::kNearJump);
   }
   __ Bind(&is_not_instance);
-  __ LoadObject(EAX, Bool::Get(false));
+  __ LoadObject(EAX, Bool::Get(negate_result));
   __ jmp(&done, Assembler::kNearJump);
 
   __ Bind(&is_instance);
-  __ LoadObject(EAX, Bool::Get(true));
+  __ LoadObject(EAX, Bool::Get(!negate_result));
   __ Bind(&done);
   __ popl(EDX);  // Remove pushed instantiator type arguments.
 }