niti: cache the frame in a local variable

expr and stmt are the most called methods.
Storing a result of a non trivial call makes sense.

Figures:

$ time ./nit test_parser.nit test_parser.nit > /dev/null
Before: user	0m8.221s
After: user	0m7.924s

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/naive_interpreter.nit b/src/naive_interpreter.nit
index 4d7495c..5c3db18 100644 (file)
--- a/src/naive_interpreter.nit
+++ b/src/naive_interpreter.nit
@@ -137,8 +137,9 @@ private class NaiveInterpreter
        # If `n' cannot be evaluated, then aborts.
        fun expr(n: AExpr): nullable Instance
        do
-               var old = self.frame.current_node
-               self.frame.current_node = n
+               var frame = self.frame
+               var old = frame.current_node
+               frame.current_node = n
                #n.debug("IN Execute expr")
                var i = n.expr(self)
                if i == null and not self.is_escaping then
@@ -146,7 +147,7 @@ private class NaiveInterpreter
                end
                #n.debug("OUT Execute expr: value is {i}")
                #if not is_subtype(i.mtype, n.mtype.as(not null)) then n.debug("Expected {n.mtype.as(not null)} got {i}")
-               self.frame.current_node = old
+               frame.current_node = old
                return i
        end
 
@@ -156,11 +157,12 @@ private class NaiveInterpreter
        fun stmt(n: nullable AExpr)
        do
                if n != null then
-                       var old = self.frame.current_node
-                       self.frame.current_node = n
+                       var frame = self.frame
+                       var old = frame.current_node
+                       frame.current_node = n
                        #n.debug("Execute stmt")
                        n.stmt(self)
-                       self.frame.current_node = old
+                       frame.current_node = old
                end
        end