Some C2 nodes share the same substrings. For example: CmpU/CmpU3 or CountedLoop/Loop. We've encountered some problems in the past that matching rules failed because an IR test relied on the uniqueness of an IRNode.XYZ match which was not the case (see https://github.com/openjdk/jdk/pull/18198#issuecomment-2214675206 as an example).

We therefore propose to update all default entries in the IRNode class to use a unique regex that only matches the node name. If some IR rules relied on the sharing feature, we should either update the rules or provide a new default entry as for example IRNode.MUL which covers "Mul(I|L|F|D)".