py: Don't allocate an extra parse node for power exponent.

dpgeorge · dpgeorge · commit 3acaa28b5258 · 2016-03-16T13:04:51.000Z
Previous to this patch, the "**b" in "a**b" had its own parse node with
just one item (the "b").  Now, the "b" is just the last element of the
power parse-node.  This saves (a tiny bit of) RAM when compiling.
diff --git a/py/compile.c b/py/compile.c
@@ -1970,6 +1970,10 @@ STATIC void compile_power(compiler_t *comp, mp_parse_node_struct_t *pns) {
     comp->func_arg_is_super = MP_PARSE_NODE_IS_ID(pns->nodes[0]) && MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]) == MP_QSTR_super;
 
     compile_generic_all_nodes(comp, pns);
+
+    if (!MP_PARSE_NODE_IS_NULL(pns->nodes[2])) {
+        EMIT_ARG(binary_op, MP_BINARY_OP_POWER);
+    }
 }
 
 STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_arglist, bool is_method_call, int n_positional_extra) {
@@ -2087,11 +2091,6 @@ STATIC void compile_power_trailers(compiler_t *comp, mp_parse_node_struct_t *pns
     }
 }
 
-STATIC void compile_power_dbl_star(compiler_t *comp, mp_parse_node_struct_t *pns) {
-    compile_node(comp, pns->nodes[0]);
-    EMIT_ARG(binary_op, MP_BINARY_OP_POWER);
-}
-
 STATIC void compile_atom_string(compiler_t *comp, mp_parse_node_struct_t *pns) {
     // a list of strings
 
diff --git a/py/grammar.h b/py/grammar.h
@@ -241,7 +241,7 @@ DEF_RULE(factor_2, c(factor_2), and(2), rule(factor_op), rule(factor))
 DEF_RULE(factor_op, nc, or(3), tok(OP_PLUS), tok(OP_MINUS), tok(OP_TILDE))
 DEF_RULE(power, c(power), and(3), rule(atom), opt_rule(power_trailers), opt_rule(power_dbl_star))
 DEF_RULE(power_trailers, c(power_trailers), one_or_more, rule(trailer))
-DEF_RULE(power_dbl_star, c(power_dbl_star), and(2), tok(OP_DBL_STAR), rule(factor))
+DEF_RULE(power_dbl_star, nc, ident | and(2), tok(OP_DBL_STAR), rule(factor))
 
 // atom: '(' [yield_expr|testlist_comp] ')' | '[' [testlist_comp] ']' | '{' [dictorsetmaker] '}' | NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False'
 // testlist_comp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )

Original file line number	Diff line number	Diff line change
`@@ -1970,6 +1970,10 @@ STATIC void compile_power(compiler_t comp, mp_parse_node_struct_t pns) {`
`1970`	`1970`	`comp->func_arg_is_super = MP_PARSE_NODE_IS_ID(pns->nodes[0]) && MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]) == MP_QSTR_super;`
`1971`	`1971`
`1972`	`1972`	`compile_generic_all_nodes(comp, pns);`
	`1973`	`+`
	`1974`	`+ if (!MP_PARSE_NODE_IS_NULL(pns->nodes[2])) {`
	`1975`	`+ EMIT_ARG(binary_op, MP_BINARY_OP_POWER);`
	`1976`	`+ }`
`1973`	`1977`	`}`
`1974`	`1978`
`1975`	`1979`	`STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_arglist, bool is_method_call, int n_positional_extra) {`
`@@ -2087,11 +2091,6 @@ STATIC void compile_power_trailers(compiler_t comp, mp_parse_node_struct_t pns`
`2087`	`2091`	`}`
`2088`	`2092`	`}`
`2089`	`2093`
`2090`		`-STATIC void compile_power_dbl_star(compiler_t comp, mp_parse_node_struct_t pns) {`
`2091`		`- compile_node(comp, pns->nodes[0]);`
`2092`		`- EMIT_ARG(binary_op, MP_BINARY_OP_POWER);`
`2093`		`-}`
`2094`		`-`
`2095`	`2094`	`STATIC void compile_atom_string(compiler_t comp, mp_parse_node_struct_t pns) {`
`2096`	`2095`	`// a list of strings`
`2097`	`2096`