Memoize irb_path existence to reduce file existence check calculating…

… eval_path

lib/irb/context.rb

@@ -555,9 +555,6 @@ def evaluate(line, line_no) # :nodoc:
         IRB.set_measure_callback
       end
 
-      # We need to use differente path to distinguish source_location of method defined in the actual file and method defined in irb session.
-      eval_path = File.exist?(irb_path) ? "#{irb_path}(#{IRB.conf[:IRB_NAME]})" : irb_path
-
       if IRB.conf[:MEASURE] && !IRB.conf[:MEASURE_CALLBACKS].empty?
         last_proc = proc do
           result = @workspace.evaluate(line, eval_path, line_no)
@@ -577,6 +574,14 @@ def evaluate(line, line_no) # :nodoc:
       set_last_value(result)
     end
 
+    private def eval_path
+      # We need to use differente path to distinguish source_location of method defined in the actual file and method defined in irb session.
+      if !defined?(@irb_path_existence) || @irb_path_existence[0] != irb_path
+        @irb_path_existence = [irb_path, File.exist?(irb_path)]
+      end
+      @irb_path_existence[1] ? "#{irb_path}(#{IRB.conf[:IRB_NAME]})" : irb_path
+    end
+
     def inspect_last_value # :nodoc:
       @inspect_method.inspect_value(@last_value)
     end

test/irb/test_context.rb

@@ -666,6 +666,15 @@ def test_lineno
         ], out)
     end
 
+    def test_eval_path
+      @context.irb_path = __FILE__
+      assert_equal("#{__FILE__}(irb)", @context.send(:eval_path))
+      @context.irb_path = 'file/does/not/exist'
+      assert_equal('file/does/not/exist', @context.send(:eval_path))
+      @context.irb_path = "#{__FILE__}(irb)"
+      assert_equal("#{__FILE__}(irb)", @context.send(:eval_path))
+    end
+
     def test_build_completor
       verbose, $VERBOSE = $VERBOSE, nil
       original_completor = IRB.conf[:COMPLETOR]