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

runtime/vm/flow_graph_compiler_arm64.cc

Index: runtime/vm/flow_graph_compiler_arm64.cc
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 5dd2308580d4db556a76e8adddb9f7df989ae81c..c7a544f51894b8c970b75f95d6f634bdee0cc2ca 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -382,11 +382,8 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
   } else {
     __ b(is_not_instance_lbl, EQ);
   }
-  // Compare if the classes are equal.
   const Register kClassIdReg = R2;
   __ LoadClassId(kClassIdReg, kInstanceReg);
-  __ CompareImmediate(kClassIdReg, type_class.id());
-  __ b(is_instance_lbl, EQ);
   // See ClassFinalizer::ResolveSuperTypeAndInterfaces for list of restricted
   // interfaces.
   // Bool interface can be implemented only by core class Bool.
@@ -396,11 +393,6 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
     __ b(is_not_instance_lbl);
     return false;
   }
-  if (type.IsDartFunctionType()) {
-    // Check if instance is a closure.
-    __ CompareImmediate(kClassIdReg, kClosureCid);
-    __ b(is_instance_lbl, EQ);
-  }
   // Custom checking for numbers (Smi, Mint, Bigint and Double).
   // Note that instance is not Smi (checked above).
   if (type.IsSubtypeOf(
@@ -413,6 +405,17 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
     GenerateStringTypeCheck(kClassIdReg, is_instance_lbl, is_not_instance_lbl);
     return false;
   }
+  if (type.IsDartFunctionType()) {
+    // Check if instance is a closure.
+    __ CompareImmediate(kClassIdReg, kClosureCid);
+    __ b(is_instance_lbl, EQ);
+    return true;  // Fall through
+  }
+  // Compare if the classes are equal.
+  if (!type_class.is_abstract()) {
+    __ CompareImmediate(kClassIdReg, type_class.id());
+    __ b(is_instance_lbl, EQ);
+  }
   // Otherwise fallthrough.
   return true;
 }