[turbofan] Optimized lowering of DYNAMIC_GLOBAL lookup slot loads.

test/unittests/compiler/js-typed-lowering-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/machine-operator.h"
@@ skipping 878 matching lines @@
     Unique<Name> name = Unique<Name>::CreateImmovable(names[i]);
     Reduction r = Reduce(graph()->NewNode(
         javascript()->LoadNamed(name, feedback), global, context,
         EmptyFrameState(), EmptyFrameState(), effect, control));
 
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(), matches[i]);
   }
 }
 
+
+// -----------------------------------------------------------------------------
+// JSLoadDynamicGlobal
+
+
+TEST_F(JSTypedLoweringTest, JSLoadDynamicGlobal) {
+  Node* const context = Parameter(Type::Any());
+  Node* const frame_state = EmptyFrameState();
+  Node* const effect = graph()->start();
+  Node* const control = graph()->start();
+  Handle<String> name = factory()->object_string();
+  VectorSlotPair feedback(Handle<TypeFeedbackVector>::null(),
+                          FeedbackVectorICSlot::Invalid());
+  for (int i = 0; i < DynamicGlobalAccess::kMaxCheckDepth; ++i) {
+    uint32_t bitset = 1 << i;  // Only single check.
+    Reduction r = Reduce(graph()->NewNode(
+        javascript()->LoadDynamicGlobal(name, bitset, feedback, NOT_CONTEXTUAL),
+        context, context, frame_state, frame_state, effect, control));
+    ASSERT_TRUE(r.Changed());
+    EXPECT_THAT(
+        r.replacement(),
+        IsPhi(kMachAnyTagged, _, _,
+              IsMerge(IsIfTrue(IsBranch(
+                          IsObjectIsSmi(IsLoadContext(
+                              ContextAccess(i, Context::EXTENSION_INDEX, false),
+                              context)),
+                          control)),
+                      _)));
+  }
+}
+
 #if V8_TURBOFAN_TARGET
 
 // -----------------------------------------------------------------------------
 // JSAdd
 
 
 TEST_F(JSTypedLoweringTest, JSAddWithString) {
   TRACED_FOREACH(LanguageMode, language_mode, kLanguageModes) {
     Node* lhs = Parameter(Type::String(), 0);
     Node* rhs = Parameter(Type::String(), 1);
@@ skipping 109 matching lines @@
   EXPECT_THAT(r.replacement(),
               IsFinish(IsAllocate(IsNumberConstant(Context::SizeFor(
                                       Context::MIN_CONTEXT_SLOTS)),
                                   effect, control),
                        _));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8