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

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 fbfe34cbbe755e127a7cfb3bd583ea14aa56dbb4..5be0f085fad1ee22c11a1c9b213fb583b7504362 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -390,11 +390,8 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
   } else {
     __ j(ZERO, is_not_instance_lbl);
   }
-  // Compare if the classes are equal.
   const Register kClassIdReg = ECX;
   __ 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.
@@ -404,11 +401,6 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
     __ jmp(is_not_instance_lbl);
     return false;
   }
-  if (type.IsDartFunctionType()) {
-    // Check if instance is a closure.
-    __ cmpl(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(
@@ -421,6 +413,17 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
     GenerateStringTypeCheck(kClassIdReg, is_instance_lbl, is_not_instance_lbl);
     return false;
   }
+  if (type.IsDartFunctionType()) {
+    // Check if instance is a closure.
+    __ cmpl(kClassIdReg, Immediate(kClosureCid));
+    __ j(EQUAL, is_instance_lbl);
+    return true;  // Fall through
+  }
+  // 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;
 }