py/compile: Combine expr, xor_expr and and_expr into one function.

This and the previous 4 commits combined have change in code size of:

   bare-arm:   -92
minimal x86:  -544
   unix x64:  -544
unix nanbox:  -712
      stm32:  -116
     cc3200:  -128
    esp8266:  -348
      esp32:  -232

2 files changed, 13 insertions, 22 deletions

diff --git a/py/compile.c b/py/compile.c
index 032e0a6ae..7daf91103 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -1985,15 +1985,6 @@ STATIC void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
     }
 }
 
-STATIC void c_binary_op(compiler_t *comp, mp_parse_node_struct_t *pns, mp_binary_op_t binary_op) {
-    int num_nodes = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
-    compile_node(comp, pns->nodes[0]);
-    for (int i = 1; i < num_nodes; i += 1) {
-        compile_node(comp, pns->nodes[i]);
-        EMIT_ARG(binary_op, binary_op);
-    }
-}
-
 STATIC void compile_test_if_expr(compiler_t *comp, mp_parse_node_struct_t *pns) {
     assert(MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[1], PN_test_if_else));
     mp_parse_node_struct_t *pns_test_if_else = (mp_parse_node_struct_t*)pns->nodes[1];
@@ -2102,16 +2093,16 @@ STATIC void compile_star_expr(compiler_t *comp, mp_parse_node_struct_t *pns) {
     compile_syntax_error(comp, (mp_parse_node_t)pns, "*x must be assignment target");
 }
 
-STATIC void compile_expr(compiler_t *comp, mp_parse_node_struct_t *pns) {
-    c_binary_op(comp, pns, MP_BINARY_OP_OR);
-}
-
-STATIC void compile_xor_expr(compiler_t *comp, mp_parse_node_struct_t *pns) {
-    c_binary_op(comp, pns, MP_BINARY_OP_XOR);
-}
-
-STATIC void compile_and_expr(compiler_t *comp, mp_parse_node_struct_t *pns) {
-    c_binary_op(comp, pns, MP_BINARY_OP_AND);
+STATIC void compile_binary_op(compiler_t *comp, mp_parse_node_struct_t *pns) {
+    MP_STATIC_ASSERT(MP_BINARY_OP_OR + PN_xor_expr - PN_expr == MP_BINARY_OP_XOR);
+    MP_STATIC_ASSERT(MP_BINARY_OP_OR + PN_and_expr - PN_expr == MP_BINARY_OP_AND);
+    mp_binary_op_t binary_op = MP_BINARY_OP_OR + MP_PARSE_NODE_STRUCT_KIND(pns) - PN_expr;
+    int num_nodes = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
+    compile_node(comp, pns->nodes[0]);
+    for (int i = 1; i < num_nodes; ++i) {
+        compile_node(comp, pns->nodes[i]);
+        EMIT_ARG(binary_op, binary_op);
+    }
 }
 
 STATIC void compile_term(compiler_t *comp, mp_parse_node_struct_t *pns) {
diff --git a/py/grammar.h b/py/grammar.h
index 37b97a191..5a5b682ac 100644
--- a/py/grammar.h
+++ b/py/grammar.h
@@ -241,9 +241,9 @@ DEF_RULE_NC(comp_op_not_in, and(2), tok(KW_NOT), tok(KW_IN))
 DEF_RULE_NC(comp_op_is, and(2), tok(KW_IS), opt_rule(comp_op_is_not))
 DEF_RULE_NC(comp_op_is_not, and(1), tok(KW_NOT))
 DEF_RULE(star_expr, c(star_expr), and(2), tok(OP_STAR), rule(expr))
-DEF_RULE(expr, c(expr), list, rule(xor_expr), tok(OP_PIPE))
-DEF_RULE(xor_expr, c(xor_expr), list, rule(and_expr), tok(OP_CARET))
-DEF_RULE(and_expr, c(and_expr), list, rule(shift_expr), tok(OP_AMPERSAND))
+DEF_RULE(expr, c(binary_op), list, rule(xor_expr), tok(OP_PIPE))
+DEF_RULE(xor_expr, c(binary_op), list, rule(and_expr), tok(OP_CARET))
+DEF_RULE(and_expr, c(binary_op), list, rule(shift_expr), tok(OP_AMPERSAND))
 DEF_RULE(shift_expr, c(term), list, rule(arith_expr), rule(shift_op))
 DEF_RULE_NC(shift_op, or(2), tok(OP_DBL_LESS), tok(OP_DBL_MORE))
 DEF_RULE(arith_expr, c(term), list, rule(term), rule(arith_op))