report_high_fanout_nets - 2022.2 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

Document ID

UG835

Release Date

2022-10-19

Version

2022.2 English

Report high fanout nets

Syntax

report_high_fanout_nets [‑file <arg>] [‑format <arg>] [‑append]
    [‑ascending] [‑timing] [‑histogram] [‑load_types] [‑clock_regions]
    [‑slr] [‑max_nets <arg>] [‑fanout_greater_than <arg>]
    [‑fanout_lesser_than <arg>] [‑name <arg>] [‑cells <args>]
    [‑clocks <args>] [‑return_string] [‑quiet] [‑verbose]

Returns

Report

Usage

Name	Description
`[-file]`	Filename to output results to. (send output to console if -file is not used)
`[-format]`	Specifies how to format the report: text, xml. Default is 'text'. Only applies if -file is used. If xml output is used, -append is not allowed. Default: text
`[-append]`	Append to existing file
`[-ascending]`	Report nets in ascending order
`[-timing]`	Report worst slack and worst delay values on nets
`[-histogram]`	Report histogram for high fanout nets
`[-load_types]`	Report load details
`[-clock_regions]`	Report clock region wise load distribution
`[-slr]`	Report SLR wise load distribution
`[-max_nets]`	Number of nets for which report is to be generated Default: 10
`[-fanout_greater_than]`	Report nets that have fanout greater than the specified integer, default 0 Default: 0
`[-fanout_lesser_than]`	Report nets that have fanout less than the specified integer, default INT_MAX Default: INT_MAX
`[-name]`	Output the results to GUI panel with this name
`[-cells]`	Report the nets of the specified cells
`[-clocks]`	Report the nets of the specified clocks
`[-return_string]`	Return report as string
`[-quiet]`	Ignore command errors
`[-verbose]`	Suspend message limits during command execution

Description

Report the fanout of nets in the design, starting with the highest fanout nets, and working down. Options allow you to control various aspects of the report.

This command can be run on an implemented design, or on the synthesized netlist. However, the results will be more complete on the implemented design.

The command returns the fanout report of nets in the design, or returns an error if it fails.

Arguments

-file <arg> - (Optional) Write the report into the specified file. The specified file will be overwritten if one already exists, unless -append is also specified.

Note: If the path is not specified as part of the file name, the file will be written into the current working directory, or the directory from which the tool was launched.

-format [ text | xml ] - (Optional) The default format of the output report is text. You can also output an XML report. XML output is only valid when -file is specified, and cannot be used with -append.

-append - (Optional) Append the output of the command to the specified file rather than overwriting it.

Note: The -append option can only be used with the -file option.

-ascending - (Optional) Report nets in ascending order.

-timing - (Optional) Add timing data to the report to display the worst slack (WNS) and worst delay on high fanout nets.

Note: The -timing option will slow the run time of report_high_fanout_nets, and is not supported for use with -histogram.

-histogram - (Optional) Format the report as a histogram showing the number of fanouts, and the number and percentage of nets with that many fanouts in the design.

Note: This option cannot be used with the following options: -ascending, -timing, -load_types, -clock_regions, -slr, -max_nets, -fanout_greater_than, and -fanout_lesser_than.

-load_types - (Optional) Reports the various load types on the net sorted in two different ways: by load types (data/clock/set/reset...) and by device resource at which loads are placed (Slices/IO...). When report_high_fanout_nets is run on the unplaced synthesized design only the load type is reported.

-clock_regions - (Optional) Report the load distribution across clock regions. This option can only be used after placement, and reports the clock regions the various loads on the net are located in.

-slr - (Optional) Report the load distribution across SLRs. This option can only be used after placement, and reports the SLRs that various loads on the net are located in, after placement.

Note: The -load_types, -slr, and -clock_regions options cannot be used together.

-max_nets <arg> - (Optional) Number of nets to report. Default: 10

-fanout_greater_than <arg> - (Optional) Report only nets that have fanout greater than the specified limit. The value can be specified as an integer, with a default value of 0.

-fanout_lesser_than <arg> - (Optional) Report only nets that have fanout less than the specified limit. The value can be specified as an integer, with a default value of INT_MAX.

-name <arg> - (Optional) The name of the High Fanout Nets Report view to display in the Vivado® IDE when run in GUI mode. If the name has already been used in an open Report view, that view will be closed and a new report opened.

-cells <args> - (Optional) Report the nets attached to the specified cell instances in the design. Cells can be passed by name, or as cell objects returned by the get_cells command.

-clocks <args> - (Optional) Report the nets of the specified clocks. The clocks can be passed by name, or as clock objects returned by the get_clocks command.

-return_string - (Optional) Directs the output to a Tcl string rather than to the standard output. The Tcl string can be captured by a variable definition and parsed or otherwise processed.

Note: This argument cannot be used with the -file option.

-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.

Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.

-verbose - (Optional) Temporarily override any message limits and return all messages from this command.

Note: Message limits can be defined with the set_msg_config command.

Examples

The following example reports the fanout of nets for the specified clocks:

report_high_fanout_nets -clocks [get_clocks gt*]

The following example reports the nets with fanouts less than 10 loads, and returns the results to a string stored as a Tcl variable:

set myRep [report_high_fanout_nets -fanout_lesser_than 10 -return_string]