[interpreter] Add a fast path for dynamic local load

src/interpreter/interpreter.cc

 // Copyright 2015 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/interpreter/interpreter.h"
 
 #include <fstream>
 #include <memory>
 
 #include "src/ast/prettyprinter.h"
@@ skipping 569 matching lines @@
 }
 
 // LdaLookupSlotInsideTypeof <name_index>
 //
 // Lookup the object with the name in constant pool entry |name_index|
 // dynamically without causing a NoReferenceError.
 void Interpreter::DoLdaLookupSlotInsideTypeof(InterpreterAssembler* assembler) {
   DoLdaLookupSlot(Runtime::kLoadLookupSlotInsideTypeof, assembler);
 }
 
+void Interpreter::DoLdaLookupContextSlot(Runtime::FunctionId function_id,
+                                         InterpreterAssembler* assembler) {
+  Node* context = __ GetContext();
+  Node* name_index = __ BytecodeOperandIdx(0);
+  Node* slot_index = __ BytecodeOperandIdx(1);
+  Node* depth = __ BytecodeOperandUImm(2);
+
+  Label slowpath(assembler, Label::kDeferred);
+
+  // Check for context extensions to allow the fast path
+  __ GotoIfHasContextExtensionUpToDepth(context, depth, &slowpath);
+
+  // Fast path does a normal load context
+  {
+    Node* slot_context = __ GetContextAtDepth(context, depth);
+    Node* result = __ LoadContextSlot(slot_context, slot_index);
+    __ SetAccumulator(result);
+    __ Dispatch();
+  }
+
+  // Slow path when we have to call out to the runtime
+  __ Bind(&slowpath);
+  {
+    Node* name = __ LoadConstantPoolEntry(name_index);
+    Node* result = __ CallRuntime(function_id, context, name);
+    __ SetAccumulator(result);
+    __ Dispatch();
+  }
+}
+
+// LdaLookupSlot <name_index>
+//
+// Lookup the object with the name in constant pool entry |name_index|
+// dynamically.
+void Interpreter::DoLdaLookupContextSlot(InterpreterAssembler* assembler) {
+  DoLdaLookupContextSlot(Runtime::kLoadLookupSlot, assembler);
+}
+
+// LdaLookupSlotInsideTypeof <name_index>
+//
+// Lookup the object with the name in constant pool entry |name_index|
+// dynamically without causing a NoReferenceError.
+void Interpreter::DoLdaLookupContextSlotInsideTypeof(
+    InterpreterAssembler* assembler) {
+  DoLdaLookupContextSlot(Runtime::kLoadLookupSlotInsideTypeof, assembler);
+}
+
 void Interpreter::DoStaLookupSlot(LanguageMode language_mode,
                                   InterpreterAssembler* assembler) {
   Node* value = __ GetAccumulator();
   Node* index = __ BytecodeOperandIdx(0);
   Node* name = __ LoadConstantPoolEntry(index);
   Node* context = __ GetContext();
   Node* result = __ CallRuntime(is_strict(language_mode)
                                     ? Runtime::kStoreLookupSlot_Strict
                                     : Runtime::kStoreLookupSlot_Sloppy,
                                 context, name, value);
@@ skipping 1866 matching lines @@
   __ StoreObjectField(generator, JSGeneratorObject::kContinuationOffset,
       __ SmiTag(new_state));
   __ SetAccumulator(old_state);
 
   __ Dispatch();
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8