forwardable.rb: optimize awy __send__

* lib/forwardable.rb (_delegator_method): remove __send__ call if
  possible, so that more optimizations will be enabled.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55376 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Sat Jun 11 13:52:33 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/forwardable.rb (_delegator_method): remove __send__ call if
+	  possible, so that more optimizations will be enabled.
+
 Sat Jun 11 11:24:36 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* enc/iso_8859.h (SHARP_s): name frequently used codepoint.

lib/forwardable.rb

@@ -195,13 +195,23 @@ module Forwardable
       accessor = "#{accessor}()"
     end
 
+    unless begin
+             iseq = RubyVM::InstructionSequence
+                    .compile("().#{method}", nil, nil, 0, false)
+           rescue SyntaxError
+           else
+             iseq.to_a.dig(-1, 1, 1, :mid) == method.to_sym
+           end
+      method = "__send__ :#{method},"
+    end
+
     line_no = __LINE__+1; str = "#{<<-"begin;"}\n#{<<-"end;"}"
     begin;
       proc do
         def #{ali}(*args, &block)
           begin
             #{accessor}
-          end.__send__ :#{method}, *args, &block
+          end.#{method} *args, &block
         end
       end
     end;