cd - a shortcut for ‘select -module <name>’¶
yosys> help cd¶
This is just a shortcut for 'select -module <modname>'.
When no module with the specified name is found, but there is a cell with the specified name in the current module, then this is equivalent to 'cd <celltype>'.
Remove trailing substrings that start with '.' in current module name until the name of a module in the current design is generated, then switch to that module. Otherwise clear the current selection.
This is just a shortcut for 'select -clear'.