give same id for same strings to simulate interning

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/BuiltinFunctions.java

@@ -974,10 +974,15 @@ long doString(String s) {
             } else if (s.length() == 1) {
                 return (~s.codePointAt(0) << IDTAG_SHIFT) | IDTAG_SPECIAL;
             } else {
-                return doGeneric(s);
+                return strHash(s);
             }
         }
 
+        @TruffleBoundary
+        private static int strHash(String s) {
+            return s.hashCode();
+        }
+
         @Specialization
         long doPString(PString s,
                         @Shared("isBuiltin") @Cached IsBuiltinClassProfile isBuiltin,