Revert "Revert "Recognize and optimize a.runtimeType == b.runtimeType pattern.""

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index c3359f1f23fe46637922f5369b64a07f62f3c7f3..622151bc0271977cc16e0fcfb61d3d4afc92aade 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -3231,6 +3231,67 @@ void PolymorphicInstanceCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 #endif
 
 
+RawType* PolymorphicInstanceCallInstr::ComputeRuntimeType(
+    const ICData& ic_data) {
+  bool is_string = true;
+  bool is_integer = true;
+  bool is_double = true;
+
+  const intptr_t num_checks = ic_data.NumberOfChecks();
+  for (intptr_t i = 0; i < num_checks; i++) {
+    const intptr_t cid = ic_data.GetReceiverClassIdAt(i);
+    is_string = is_string && RawObject::IsStringClassId(cid);
+    is_integer = is_integer && RawObject::IsIntegerClassId(cid);
+    is_double = is_double && (cid == kDoubleCid);
+  }
+
+  if (is_string) {
+    return Type::StringType();
+  } else if (is_integer) {
+    return Type::IntType();
+  } else if (is_double) {
+    return Type::Double();
+  }
+
+  return Type::null();
+}
+
+
+Definition* PolymorphicInstanceCallInstr::Canonicalize(FlowGraph* flow_graph) {
+  if (!HasSingleRecognizedTarget() || with_checks()) {
+    return this;
+  }
+
+  const Function& target = Function::Handle(ic_data().GetTargetAt(0));
+  if (target.recognized_kind() == MethodRecognizer::kObjectRuntimeType) {
+    const AbstractType& type =
+        AbstractType::Handle(ComputeRuntimeType(ic_data()));
+    if (!type.IsNull()) {
+      return flow_graph->GetConstant(type);
+    }
+  }
+
+  return this;
+}
+
+
+Definition* StaticCallInstr::Canonicalize(FlowGraph* flow_graph) {
+  if (!FLAG_precompiled_mode) {
+    return this;
+  }
+
+  if (function().recognized_kind() == MethodRecognizer::kObjectRuntimeType) {
+    if (input_use_list() == NULL) {
+      // This function has only environment uses. In precompiled mode it is
+      // fine to remove it - because we will never deoptimize.
+      return flow_graph->constant_dead();
+    }
+  }
+
+  return this;
+}
+
+
 LocationSummary* StaticCallInstr::MakeLocationSummary(Zone* zone,
                                                       bool optimizing) const {
   return MakeCallSummary(zone);