Example

. dependency graph for real id1, id2, id3

. put a dummy synthesized attribute b for a semantic rule that consists of a procedure call

The figure shows the dependency graph for the statement real id1, id2, id3 along with the parse tree. Procedure calls can be thought of as rules defining the values of dummy synthesized attributes of the nonterminal on the left side of the associated production. Blue arrows constitute the dependency graph and black lines, the parse tree. Each of the semantic rules addtype (id.entry, L.in) associated with the L productions leads to the creation of the dummy attribute.