Scoped Queries Guidelines - Scoped Queries Guidelines - 2026.1 English - UG903

For this flow to work smoothly, write XDC constraints so their effects remain local to the IP or sub-module instance. Vivado can scope queries to a specific hierarchy level, as shown previously in Constraints Scoping. When developing constraints for an IP or sub-level module, understand how the query commands behave.

• Limit cell/net/pin queries to the scoped instance and its sub-levels using the following command:

  get_cells <name pattern>
  get_nets <name pattern>
  get_pins <name pattern>

  • The NAME property shows the full path from the top level, rather than relative to the scoped instance.
  • Use the -filter option with a glob match that starts with * for name patterns as shown in the following example:

    get_nets -hierarchical -filter {NAME =~ *clk}

• If the net connects directly to a top-level port, get_ports returns the top-level port; otherwise, it returns a hierarchical pin.
• Limit netlist helper commands to the scope of the current instance by using the following commands:
  • all_ffs
  • all_latches
  • all_rams
  • all_registers
  • all_dsps
  • all_hsios
• Avoid I/O helper commands in scoped XDC files:
  • all_inputs
  • all_outputs
• Clock commands are not scoped and returns all timing clocks of your design.
  • get_clocks
  • all_clocks
• Retrieve top-level or local clock by probing the netlist with get_clocks -of_objects.
  • Use the following command for a clock entering the current instance:

    get_clocks -of_objects [get_ports <interfacePinName>]

  • Use the following command for a clock generated inside the current instance, where instName is a clock generator instance:

    get_clocks -of_objects [get_pins <instName/outPin>]

• Query objects in the design using a parent object context with the -of_objects option:

  get_pins -leaf -of_objects [get_nets local_net]

• Query top‑level ports connected to current instance interface nets:

  get_ports -of_objects [get_nets <scoped_instance_net>]

• Avoid querying IP or sub‑module interface pins directly. For example, get_pins clk returns an error.
• Scope path tracing commands so all_fanin and all_fanout traverse only within the scoped design and stop at its boundary.
• Target specific objects efficiently with get_cells, get_pins, or get_nets. Use specific patterns instead of broad commands like the following:

  all_registers -clock

  Broad queries can return large collections of objects, which can negatively impact runtime.