[interpreter] Add fast path for dynamic global lookups

src/interpreter/bytecode-array-builder.h

Index: src/interpreter/bytecode-array-builder.h
diff --git a/src/interpreter/bytecode-array-builder.h b/src/interpreter/bytecode-array-builder.h
index eacd35b09d58661a408168851caf077c76052003..ecca192252f5ea1480e00e5888ebd9b290b6e5b5 100644
--- a/src/interpreter/bytecode-array-builder.h
+++ b/src/interpreter/bytecode-array-builder.h
@@ -138,6 +138,13 @@ class BytecodeArrayBuilder final : public ZoneObject {
                                               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);