verilator_coverage - Man Page

Verilator coverage analyzer


    verilator_coverage --help
    verilator_coverage --version

    verilator_coverage --annotate <obj>

    verilator_coverage  -write merged.dat -read <datafiles>...

    verilator_coverage  -write-info -read <datafiles>...

Verilator_coverage processes Verilator coverage reports.

With --anotate, it reads the specified data file and generates annotated source code with coverage metrics annotated.  If multiple coverage points exist on the same line, additional lines will be inserted to report the additional points.

Additional Verilog-standard arguments specify the search paths necessary to find the source code that the coverage analysis was performed on.

To get correct coverage percentages, you may wish to read logs/coverage.dat into Emacs and do a M-x keep-lines to include only those statistics of interest.

For Verilog conditions that should never occur, you should add a $stop statement.  This will remove the coverage during the next build.



Specify input data file, may be repeated to read multiple inputs.  If no data file is specified, by default coverage.dat is read.

--annotate output_directory

Sprcifies the directory name that source files with annotated coverage data should be written to.


Specifies all files should be shown.  By default, only those source files which have low coverage are written to the output directory.

--annotate-min count

Specifies the minimum occurrence count that should be flagged if the coverage point does not include a specified threshold.  Defaults to 10.


Displays this message and program version and exits.


Print an experimental report listing the relative importance of each test in covering all of the coverage points.  The report shows “Covered” which indicates the number of points that test covers; a test is considered to cover a point if it has a bucket count of at least 1. The “rank” column has a higher number t indicate the test is more important, and rank 0 means the test does not need to be run to cover the points.  “RankPts” indicates the number of coverage points this test will contribute to overall coverage if all tests are run in the order of highest to lowest rank.


When using --write to combine coverage data, unlink all input files after the output has been created.


Displays program version and exits.

--write filename

Specifies the aggregate coverage results, summed across all the files, should be written to the given filename in verilator_coverage data format. This is useful in scripts to combine many sequential runs into one master coverage file.


Specifies the aggregate coverage results, summed across all the files, should be written to the given filename in lcov .info format. This may be used to use lcov to aggregate or generate reports.

The info format loses data compared to the Verilator coverage data format; the info will all forms of coverage converted to line style coverage, and if there are multiple coverage points on a single line, the minimum coverage across those points will be used to report coverage of the line.

Verilog Arguments

The following arguments are compatible with GCC, VCS and most Verilog programs.


Defines the extensions for Verilog files.

+define+var+value =item -Dvar=value

Defines the given variable.

+incdir+dir =item -Idir

Specifies a directory for finding include files.

-f file

Specifies a file containing additional command line arguments.

-y dir

Specifies a module search directory.


The latest version is available from <>.

Copyright 2003-2021 by Wilson Snyder. This program is free software; you can redistribute it and/or modify the Verilator internals under the terms of either the GNU Lesser General Public License Version 3 or the Perl Artistic License Version 2.0.

SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0


Wilson Snyder <>

See Also

verilator, lcov

“verilator_coverage --help” which is the source for this document.


2021-01-27 perl v5.32.1 User Contributed Perl Documentation