compile.c: optimize literal nodes

* compile.c (static_literal_node_p): optimize literal nodes for
  true, false, and nil, which are static literals in specific
  nodes but not in NODE_LIT.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57025 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

compile.c

@@ -2961,6 +2961,29 @@ enum compile_array_type_t {
     COMPILE_ARRAY_TYPE_ARGS
 };
 
+static int
+static_literal_node_p(NODE *node, VALUE *val)
+{
+    node = node->nd_head;
+    switch (nd_type(node)) {
+      case NODE_LIT:
+	*val = node->nd_lit;
+	break;
+      case NODE_NIL:
+	*val = Qnil;
+	break;
+      case NODE_TRUE:
+	*val = Qtrue;
+	break;
+      case NODE_FALSE:
+	*val = Qfalse;
+	break;
+      default:
+	return FALSE;
+    }
+    return TRUE;
+}
+
 static int
 compile_array_(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE* node_root,
 	       enum compile_array_type_t type, struct rb_call_info_kw_arg **keywords_ptr, int popped)
@@ -2985,6 +3008,7 @@ compile_array_(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE* node_root,
 	while (node) {
 	    NODE *start_node = node, *end_node;
 	    NODE *kw = 0;
+	    VALUE elem[2];
 	    const int max = 0x100;
 	    DECL_ANCHOR(anchor);
 	    INIT_ANCHOR(anchor);
@@ -3004,7 +3028,7 @@ compile_array_(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE* node_root,
 		    }
 		    break;
 		}
-		if (opt_p && nd_type(node->nd_head) != NODE_LIT) {
+		if (opt_p && !static_literal_node_p(node, elem)) {
 		    opt_p = 0;
 		}
 
@@ -3024,15 +3048,15 @@ compile_array_(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE* node_root,
 		    node = start_node;
 
 		    while (node != end_node) {
-			rb_ary_push(ary, node->nd_head->nd_lit);
+			static_literal_node_p(node, elem);
+			rb_ary_push(ary, elem[0]);
 			node = node->nd_next;
 		    }
-		    while (node && nd_type(node->nd_head) == NODE_LIT &&
-			   node->nd_next && nd_type(node->nd_next->nd_head) == NODE_LIT) {
-			rb_ary_push(ary, node->nd_head->nd_lit);
-			node = node->nd_next;
-			rb_ary_push(ary, node->nd_head->nd_lit);
-			node = node->nd_next;
+		    while (node && node->nd_next &&
+			   static_literal_node_p(node, &elem[0]) &&
+			   static_literal_node_p(node->nd_next, &elem[1])) {
+			rb_ary_cat(ary, elem, 2);
+			node = node->nd_next->nd_next;
 			len++;
 		    }