[interpreter] Add fast path for dynamic global lookups

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index 43ab0e3abe0e0103ac6fde664fcd89138360f67c..3820f4fb5a55a1fc9f6f3415858dee7ba181458a 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -1977,6 +1977,12 @@ void BytecodeGenerator::VisitVariableLoad(Variable* variable,
           BuildHoleCheckForVariableLoad(variable);
           break;
         }
+        case DYNAMIC_GLOBAL: {
+          int depth = scope()->ContextChainLengthUntilOutermostSloppyEval();
+          builder()->LoadLookupGlobalSlot(variable->name(), typeof_mode,
+                                          feedback_index(slot), depth);
+          break;
+        }
         default:
           builder()->LoadLookupSlot(variable->name(), typeof_mode);

[rmcilroy, 2016/09/19 09:04:29]

Just to check, does this branch ever get hit? If not it would be great to remove
the bytecode.

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

I still see one generation, in WithStatement.golden, for the code

  with ({x:42}) { return x; }

       }