Introduce `rb_code_location_t`

`rb_code_location_t` has two integers, lineno and column, which point to
one location on a code.  Now `rb_code_location_t` is used instead of
`VALUE nd_location`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60652 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

node.c

@@ -1058,11 +1058,12 @@ void
 rb_node_init(NODE *n, enum node_type type, VALUE a0, VALUE a1, VALUE a2)
 {
     n->flags = T_NODE;
-    n->nd_location = 0;
+    nd_set_type(n, type);
     n->u1.value = a0;
     n->u2.value = a1;
     n->u3.value = a2;
-    nd_set_type(n, type);
+    n->nd_first_loc.lineno = 0;
+    n->nd_first_loc.column = 0;
 }
 
 typedef struct node_buffer_elem_struct {

node.h

@@ -222,9 +222,13 @@ enum node_type {
 #define NODE_LAST        NODE_LAST
 };
 
+typedef struct rb_code_location_struct {
+    int lineno;
+    int column;
+} rb_code_location_t;
+
 typedef struct RNode {
     VALUE flags;
-    VALUE nd_location;		/* lineno and column */
     union {
 	struct RNode *node;
 	ID id;
@@ -247,6 +251,7 @@ typedef struct RNode {
 	long cnt;
 	VALUE value;
     } u3;
+    rb_code_location_t nd_first_loc;
 } NODE;
 
 #define RNODE(obj)  (R_CAST(RNode)(obj))
@@ -270,13 +275,11 @@ typedef struct RNode {
 #define nd_line(n) (int)(((SIGNED_VALUE)(n)->flags)>>NODE_LSHIFT)
 #define nd_set_line(n,l) \
     (n)->flags=(((n)->flags&~((VALUE)(-1)<<NODE_LSHIFT))|((VALUE)((l)&NODE_LMASK)<<NODE_LSHIFT))
-#define nd_column(n) (int)((n)->nd_location & 0xffff)
-#define nd_set_column(n, v) \
-    (n)->nd_location = ((n)->nd_location & ~0xffff) | ((v) > 0xffff ? 0xffff : ((unsigned int)(v)) & 0xffff)
 
-#define nd_lineno(n) (int)(((n)->nd_location >> 16) & 0xffff)
-#define nd_set_lineno(n, v) \
-    (n)->nd_location = ((n)->nd_location & ~0xffff0000) | (((v) > 0xffff ? 0xffff : ((unsigned int)(v)) & 0xffff) << 16)
+#define nd_column(n) ((int)((n)->nd_first_loc.column))
+#define nd_set_column(n, v) ((n)->nd_first_loc.column = (v))
+#define nd_lineno(n) ((int)((n)->nd_first_loc.lineno))
+#define nd_set_lineno(n, v) ((n)->nd_first_loc.lineno = (v))
 
 #define nd_head  u1.node
 #define nd_alen  u2.argc