[interpreter] Add fast path for dynamic global lookups

src/interpreter/bytecode-array-builder.h

 // 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.
 
 #ifndef V8_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_
 #define V8_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_
 
 #include "src/ast/ast.h"
 #include "src/interpreter/bytecode-array-writer.h"
 #include "src/interpreter/bytecode-register-allocator.h"
@@ skipping 120 matching lines @@
   BytecodeArrayBuilder& LoadLookupSlot(const Handle<String> name,
                                        TypeofMode typeof_mode);
 
   // Lookup the variable with |name|, which is known to be at |slot_index| at
   // |depth| in the context chain if not shadowed by a context extension
   // somewhere in that context chain.
   BytecodeArrayBuilder& LoadLookupContextSlot(const Handle<String> name,
                                               TypeofMode typeof_mode,
                                               int slot_index, int depth);
 
+  // Lookup the variable with |name|, which is known to be at |feedback_slot| in

[mythria, 2016/09/19 09:26:53]

nit: update the comment. I think feedback is stored at the |feedback_slot|.

[Leszek Swirski, 2016/09/19 10:34:51]

Done.

+  // the global context if not shadowed by a context extension somewhere up to
+  // |depth| in that context chain.
+  BytecodeArrayBuilder& LoadLookupGlobalSlot(const Handle<String> name,
+                                             TypeofMode typeof_mode,
+                                             int feedback_slot, int depth);
+
   // Store value in the accumulator into the variable with |name|.
   BytecodeArrayBuilder& StoreLookupSlot(const Handle<String> name,
                                         LanguageMode language_mode);
 
   // Create a new closure for a SharedFunctionInfo which will be inserted at
   // constant pool index |entry|.
   BytecodeArrayBuilder& CreateClosure(size_t entry, int flags);
 
   // Create a new local context for a |scope_info| and a closure which should be
   // in the accumulator.
@@ skipping 261 matching lines @@
   static int const kNoFeedbackSlot = 0;
 
   DISALLOW_COPY_AND_ASSIGN(BytecodeArrayBuilder);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_BYTECODE_ARRAY_BUILDER_H_