On Fri, 19 Feb 2021 at 10:31, Shuai Wang via Gcc <gcc@gcc.gnu.org> wrote: > > Hello, > > I noticed that tree_node is implemented as a union ( > https://code.woboq.org/gcc/gcc/tree-core.h.html#tree_node). However, I > cannot find a way of checking whether the current tree_node is really a > base or type. > > For instance, currently when I am using: > > is_gimple_constant(v) > > Given `v` as a tree type but NOT base type, the above statement would > crash. I am thinking there should be a method like: > > is_tree_base(v) == false > > or something like this; however, I couldn't find one. Can anyone shed some > lights on this? Thank you very much! If you want to ascertain which class the tree node belongs to, you can use either TREE_CODE, or one of the _P macros defined in tree.h. If you use an accessor that needs tree node belonging to a certain class, then you need to check for it before hand. For example before using DECL_NAME on a tree node, you need to explicitly check if it's indeed a decl_node using DECL_P. For is_gimple_constant(v), it will return true if v is a one of the constant nodes (*_CST), and false otherwise, so I don't see how it will crash if you pass a non-constant node ?
Thanks, Prathamesh > > best, > Shuai
