Revert "VM: Constant fold more loads from constants in the optimizer."

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 d43bd9fc983097a2bb0bf4caa31fa62b4ec0dfc0..c37c414e0e8a7d9415caf0cbd3580ce755f84072 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -2121,72 +2121,40 @@ Definition* MathUnaryInstr::Canonicalize(FlowGraph* flow_graph) {
 }
 
 
-bool LoadFieldInstr::Evaluate(const Object& instance, Object* result) {
-  if (field() == NULL || !field()->is_final() || !instance.IsInstance()) {
-    return false;
-  }
-
-  // Check that instance really has the field which we
-  // are trying to load from.
-  Class& cls = Class::Handle(instance.clazz());
-  while (cls.raw() != Class::null() && cls.raw() != field()->Owner()) {
-    cls = cls.SuperClass();
-  }
-  if (cls.raw() != field()->Owner()) {
-    // Failed to find the field in class or its superclasses.
-    return false;
-  }
-
-  // Object has the field: execute the load.
-  *result = Instance::Cast(instance).GetField(*field());
-  return true;
-}
-
-
 Definition* LoadFieldInstr::Canonicalize(FlowGraph* flow_graph) {
   if (!HasUses()) return NULL;
-
-  if (IsImmutableLengthLoad()) {
-    // For fixed length arrays if the array is the result of a known constructor
-    // call we can replace the length load with the length argument passed to
-    // the constructor.
-    StaticCallInstr* call =
-        instance()->definition()->OriginalDefinition()->AsStaticCall();
-    if (call != NULL) {
-      if (call->is_known_list_constructor() &&
-          IsFixedLengthArrayCid(call->Type()->ToCid())) {
-        return call->ArgumentAt(1);
-      }
-    }
-
-    CreateArrayInstr* create_array =
-        instance()->definition()->OriginalDefinition()->AsCreateArray();
-    if ((create_array != NULL) &&
-        (recognized_kind() == MethodRecognizer::kObjectArrayLength)) {
-      return create_array->num_elements()->definition();
+  if (!IsImmutableLengthLoad()) return this;
+
+  // For fixed length arrays if the array is the result of a known constructor
+  // call we can replace the length load with the length argument passed to
+  // the constructor.
+  StaticCallInstr* call =
+      instance()->definition()->OriginalDefinition()->AsStaticCall();
+  if (call != NULL) {
+    if (call->is_known_list_constructor() &&
+        IsFixedLengthArrayCid(call->Type()->ToCid())) {
+      return call->ArgumentAt(1);
     }
+  }
 
-    // For arrays with guarded lengths, replace the length load
-    // with a constant.
-    LoadFieldInstr* load_array =
-        instance()->definition()->OriginalDefinition()->AsLoadField();
-    if (load_array != NULL) {
-      const Field* field = load_array->field();
-      if ((field != NULL) && (field->guarded_list_length() >= 0)) {
-        return flow_graph->GetConstant(
-            Smi::Handle(Smi::New(field->guarded_list_length())));
-      }
-    }
+  CreateArrayInstr* create_array =
+      instance()->definition()->OriginalDefinition()->AsCreateArray();
+  if ((create_array != NULL) &&
+      (recognized_kind() == MethodRecognizer::kObjectArrayLength)) {
+    return create_array->num_elements()->definition();
   }
 
-  // Try folding away loads from constant objects.
-  if (instance()->BindsToConstant()) {
-    Object& result = Object::Handle();
-    if (Evaluate(instance()->BoundConstant(), &result)) {
-      return flow_graph->GetConstant(result);
+  // For arrays with guarded lengths, replace the length load
+  // with a constant.
+  LoadFieldInstr* load_array =
+      instance()->definition()->OriginalDefinition()->AsLoadField();
+  if (load_array != NULL) {
+    const Field* field = load_array->field();
+    if ((field != NULL) && (field->guarded_list_length() >= 0)) {
+      return flow_graph->GetConstant(
+          Smi::Handle(Smi::New(field->guarded_list_length())));
     }
   }
-
   return this;
 }