26.15.3 Preview Structural Changes in the Design Hierarchy
Any change to a module or entity definition, like new ports or new signals being added, affects all its instances. Before proceeding to source code changes, you can preview the design structural changes.
output instance is the module instance where the connection starts. It outputs the signal that will be connected.
output module is the module being instantiated as an
input instance is the module instance where the connection ends. It inputs the signal that will be connected.
input module is the module being instantiated as an
closest parent instance is the parent instance through which a signal is routed to connect the ports leading from the
output instance to the
input instance across the design hierarchy. No ports will be added to the
closest parent instance. The
closest parent module is the module corresponding to the
closest parent instance.
relevant modules are the modules that will change by adding new ports and/or new signals.
relevant instances are instances of
Ports are added only to modules that are instantiated on the paths leading from the
output module instance and the
input module instance to the
closest parent instance. Ports are added to the
output module or the
input module only if the connection is not using an existing port.
All the instances that will not change are grayed out. All
relevant instances are highlighted. If you hide the irrelevant instances, only the grayed out instances enclosing
relevant instances are kept in the tree.
The following filters in the
Connect Instances Toolbar
help you understand the structural changes:
Show Design Hierarchy to see the unfiltered design hierarchy.
Minimal Path highlights just the affected path from the
output instance to the
input instance. It includes the
closest parent instance through which the signal is routed. It presents the connection between the instances you've selected without considering the side effects caused by other instances.
Direct Changes highlights all the "similar" instances that are connected. It practically presents all the instances of the
closest parent module.
Indirect Changes highlights all the changes in the design that are not
Direct Changes. For example an
output module could be instantiated outside the
closest parent module design hierarchy, in "isolation" from the
input module. As such these may be unexpected changes that lead to dangling ports.
All Changes highlights all the changes in the design. Here you see all the
relevant instances. It is the union of
Direct Changes and
Note 1: Changes are computed on all tops.
We connect blue1: Blue (
output instance) to d1 : D (
input instance). b1 : B is the
closest parent instance and B is the
closest parent module. The
relevant instances are highlighted.
The structural changes of the filters above are:
Show Design Hierarchy
IMPORTANT NOTE: This feature is currently supported only in the Old Design Hierarchy View.
To switch to/from the Old Design Hierarchy View, go to
Window > Preferences > DVT and toggle
Switch to Old Design Hierarchy View