Force context allocation for variables in generator scopes.

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4374 matching lines @@
   FunctionLiteral::IsParenthesizedFlag parenthesized = parenthesized_function_
       ? FunctionLiteral::kIsParenthesized
       : FunctionLiteral::kNotParenthesized;
   FunctionLiteral::IsGeneratorFlag generator = is_generator
       ? FunctionLiteral::kIsGenerator
       : FunctionLiteral::kNotGenerator;
   AstProperties ast_properties;
   // Parse function body.
   { FunctionState function_state(this, scope, is_generator, isolate());
     top_scope_->SetScopeName(function_name);
+    // For generators, allocating variables in contexts is currently a win
+    // because it minimizes the work needed to suspend and resume an activation.
+    if (is_generator) top_scope_->ForceContextAllocation();
 
     //  FormalParameterList ::
     //    '(' (Identifier)*[','] ')'
     Expect(Token::LPAREN, CHECK_OK);
     scope->set_start_position(scanner().location().beg_pos);
     Scanner::Location name_loc = Scanner::Location::invalid();
     Scanner::Location dupe_loc = Scanner::Location::invalid();
     Scanner::Location reserved_loc = Scanner::Location::invalid();
 
     bool done = (peek() == Token::RPAREN);
@@ skipping 1597 matching lines @@
       ASSERT(info->isolate()->has_pending_exception());
     } else {
       result = parser.ParseProgram();
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal