py: Slightly simplify compile and emit of star/double-star arguments.

Saves a few bytes of code space and eliminates need for rot_two
bytecode (hence saving RAM and execution time, by a tiny bit).

py/compile.c

@@ -2252,11 +2252,18 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar
     }
 
     // compile the star/double-star arguments if we had them
-    if (star_args_node != NULL) {
-        compile_node(comp, star_args_node->nodes[0]);
-    }
-    if (dblstar_args_node != NULL) {
-        compile_node(comp, dblstar_args_node->nodes[0]);
+    // if we had one but not the other then we load "null" as a place holder
+    if (star_flags != 0) {
+        if (star_args_node == NULL) {
+            EMIT(load_null);
+        } else {
+            compile_node(comp, star_args_node->nodes[0]);
+        }
+        if (dblstar_args_node == NULL) {
+            EMIT(load_null);
+        } else {
+            compile_node(comp, dblstar_args_node->nodes[0]);
+        }
     }
 
     // emit the function/method call

py/emitbc.c

@@ -859,14 +859,6 @@ void mp_emit_bc_make_closure(emit_t *emit, scope_t *scope, mp_uint_t n_closed_ov
 
 STATIC void emit_bc_call_function_method_helper(emit_t *emit, mp_int_t stack_adj, mp_uint_t bytecode_base, mp_uint_t n_positional, mp_uint_t n_keyword, mp_uint_t star_flags) {
     if (star_flags) {
-        if (!(star_flags & MP_EMIT_STAR_FLAG_SINGLE)) {
-            // load dummy entry for non-existent pos_seq
-            mp_emit_bc_load_null(emit);
-            mp_emit_bc_rot_two(emit);
-        } else if (!(star_flags & MP_EMIT_STAR_FLAG_DOUBLE)) {
-            // load dummy entry for non-existent kw_dict
-            mp_emit_bc_load_null(emit);
-        }
         emit_bc_pre(emit, stack_adj - (mp_int_t)n_positional - 2 * (mp_int_t)n_keyword - 2);
         emit_write_bytecode_byte_uint(emit, bytecode_base + 1, (n_keyword << 8) | n_positional); // TODO make it 2 separate uints?
     } else {

py/emitnative.c

@@ -2316,14 +2316,6 @@ STATIC void emit_native_call_function(emit_t *emit, mp_uint_t n_positional, mp_u
     } else {
         assert(vtype_fun == VTYPE_PYOBJ);
         if (star_flags) {
-            if (!(star_flags & MP_EMIT_STAR_FLAG_SINGLE)) {
-                // load dummy entry for non-existent pos_seq
-                emit_native_load_null(emit);
-                emit_native_rot_two(emit);
-            } else if (!(star_flags & MP_EMIT_STAR_FLAG_DOUBLE)) {
-                // load dummy entry for non-existent kw_dict
-                emit_native_load_null(emit);
-            }
             emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_positional + 2 * n_keyword + 3); // pointer to args
             emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW_VAR, 0, REG_ARG_1, n_positional | (n_keyword << 8), REG_ARG_2);
             emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);
@@ -2340,14 +2332,6 @@ STATIC void emit_native_call_function(emit_t *emit, mp_uint_t n_positional, mp_u
 
 STATIC void emit_native_call_method(emit_t *emit, mp_uint_t n_positional, mp_uint_t n_keyword, mp_uint_t star_flags) {
     if (star_flags) {
-        if (!(star_flags & MP_EMIT_STAR_FLAG_SINGLE)) {
-            // load dummy entry for non-existent pos_seq
-            emit_native_load_null(emit);
-            emit_native_rot_two(emit);
-        } else if (!(star_flags & MP_EMIT_STAR_FLAG_DOUBLE)) {
-            // load dummy entry for non-existent kw_dict
-            emit_native_load_null(emit);
-        }
         emit_get_stack_pointer_to_reg_for_pop(emit, REG_ARG_3, n_positional + 2 * n_keyword + 4); // pointer to args
         emit_call_with_2_imm_args(emit, MP_F_CALL_METHOD_N_KW_VAR, 1, REG_ARG_1, n_positional | (n_keyword << 8), REG_ARG_2);
         emit_post_push_reg(emit, VTYPE_PYOBJ, REG_RET);