Change NODE layout for pattern matching

I prefer pconst to be the first element of NODE.

  Before:

       | ARYPTN | FNDPTN | HSHPTN
    ---+--------+--------+-----------
    u1 | imemo  | imemo  | pkwargs
    u2 | pconst | pconst | pconst
    u3 | apinfo | fpinfo | pkwrestarg

  After:

       | ARYPTN | FNDPTN | HSHPTN
    ---+--------+--------+-----------
    u1 | pconst | pconst | pconst
    u2 | imemo  | imemo  | pkwargs
    u3 | apinfo | fpinfo | pkwrestarg

node.c

@@ -1328,9 +1328,11 @@ mark_ast_value(void *ctx, NODE * node)
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
+        rb_gc_mark_movable(node->nd_lit);
+        break;
       case NODE_ARYPTN:
       case NODE_FNDPTN:
-        rb_gc_mark_movable(node->nd_lit);
+        rb_gc_mark_movable(node->nd_rval);
         break;
       default:
         rb_bug("unreachable node %s", ruby_node_name(nd_type(node)));
@@ -1355,9 +1357,11 @@ update_ast_value(void *ctx, NODE * node)
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
+        node->nd_lit = rb_gc_location(node->nd_lit);
+        break;
       case NODE_ARYPTN:
       case NODE_FNDPTN:
-        node->nd_lit = rb_gc_location(node->nd_lit);
+        node->nd_rval = rb_gc_location(node->nd_rval);
         break;
       default:
         rb_bug("unreachable");

node.h

@@ -273,8 +273,8 @@ typedef struct RNode {
 
 #define nd_brace u2.argc
 
-#define nd_pkwargs    u1.node
+#define nd_pconst     u1.node
-#define nd_pconst     u2.node
+#define nd_pkwargs    u2.node
 #define nd_pkwrestarg u3.node
 
 #define nd_apinfo u3.apinfo

parse.y

@@ -11606,7 +11606,7 @@ new_array_pattern_tail(struct parser_params *p, NODE *pre_args, int has_rest, ID
     VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
     struct rb_ary_pattern_info *apinfo = ZALLOC(struct rb_ary_pattern_info);
     rb_imemo_tmpbuf_set_ptr(tmpbuf, apinfo);
-    node = NEW_NODE(NODE_ARYPTN, tmpbuf, 0, apinfo, loc);
+    node = NEW_NODE(NODE_ARYPTN, 0, tmpbuf, apinfo, loc);
     RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
 
     apinfo->pre_args = pre_args;
@@ -11645,7 +11645,7 @@ new_find_pattern_tail(struct parser_params *p, ID pre_rest_arg, NODE *args, ID p
     VALUE tmpbuf = rb_imemo_tmpbuf_auto_free_pointer();
     struct rb_fnd_pattern_info *fpinfo = ZALLOC(struct rb_fnd_pattern_info);
     rb_imemo_tmpbuf_set_ptr(tmpbuf, fpinfo);
-    node = NEW_NODE(NODE_FNDPTN, tmpbuf, 0, fpinfo, loc);
+    node = NEW_NODE(NODE_FNDPTN, 0, tmpbuf, fpinfo, loc);
     RB_OBJ_WRITTEN(p->ast, Qnil, tmpbuf);
 
     fpinfo->pre_rest_arg = pre_rest_arg ? assignable(p, pre_rest_arg, 0, loc) : NODE_SPECIAL_NO_NAME_REST;
@@ -11679,7 +11679,7 @@ new_hash_pattern_tail(struct parser_params *p, NODE *kw_args, ID kw_rest_arg, co
 	kw_rest_arg_node = NULL;
     }
 
-    node = NEW_NODE(NODE_HSHPTN, kw_args, 0, kw_rest_arg_node, loc);
+    node = NEW_NODE(NODE_HSHPTN, 0, kw_args, kw_rest_arg_node, loc);
 
     p->ruby_sourceline = saved_line;
     return node;