verilator/docs/guide/exe_verilator_coverage.rst

.. Copyright 2003-2024 by Wilson Snyder.
.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0

verilator_coverage
==================

Verilator_coverage processes Verilated model-generated coverage reports.

With `--annotate`, it reads the specified coverage data file and generates
annotated source code with coverage metrics annotated.  With
`--annotate-points` the coverage points corresponding to each line are also
shown.

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

To filter those items to be included in coverage, you may read
logs/coverage.dat into an editor and do a M-x keep-lines to include only
those statistics of interest and save to a new .dat file.

For Verilog conditions that should never occur, either add a $stop
statement to the appropriate statement block, or see
:option:`/*verilator&32;coverage_off*/`.  This will remove the coverage
points after the model is re-Verilated.

For an overview of the use of verilator_coverage, see :ref:`Coverage Analysis`.


verilator_coverage Example Usage
--------------------------------

..

    verilator_coverage --help
    verilator_coverage --version

    verilator_coverage --annotate <obj>

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

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


verilator_coverage Arguments
----------------------------

.. program:: verilator_coverage

.. option:: <filename>

Specifies the input coverage data file.  Multiple filenames may be provided
to read multiple inputs.  If no data file is specified, by default,
"coverage.dat" will be read.

.. option:: --annotate <output_directory>

Specifies the directory name to which source files with annotated coverage
data should be written.

Converting from the Verilator coverage data format to the info format is
lossy; the info will have all forms of coverage merged line coverage, and
if there are multiple coverage points on a single line they will merge.
The minimum coverage across all merged points will be used to report
coverage of the line.

Coverage data is annotated at the beginning of the line and is formatted
as a special character followed by the number of coverage hits. The special
characters " ,%,+,-" indicate summary of the coverage, and allow use of grep
to filter the report.

* " " (whitespace) indicates that all points on the line are above the coverage limit.
* "%" indicates at least one point on the line was below the coverage limit.
* "+" coverage point was at or above the limit. Only used with :option:`--annotate-points`.
* "-" coverage point was below the limit.  Only used with :option:`--annotate-points`.

.. code-block::

   100000  input logic a;   // Begins with whitespace, because
                            // number of hits (100000) is above the limit.
  +100000  point: comment=a // Begins with +, because
                            // number of hits (100000) is above the limit.
  %000000  input logic b;   // Begins with %, because
                            // number of hits (0) is below the limit.
  -000000  point: comment=b // Begins with -, because
                            // number of hits (0) is below the limit.

.. option:: --annotate-all

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

This option should be used together with :option:`--annotate`.

.. option:: --annotate-min <count>

Specifies the threshold (<count>) below which coverage point is considered
sufficient. If the threshold is not exceeded, then the annotation will begin
with a "%" symbol to indicate the coverage is insufficient.

The <count> threshold defaults to 10.

This option should be used together with :option:`--annotate`.


.. option:: --annotate-points

Specifies all coverage points should be shown after each line of text.  By
default, only source lines are shown.

.. code-block::

  100000  input logic a, b, c;
 +100000 point: comment=a // These lines are only shown
 +200000 point: comment=b // with option --annotate-points
 +300000 point: comment=c // enabled.


This option should be used together with :option:`--annotate`.

.. option:: --help

Displays a help summary, the program version, and exits.

.. option:: --rank

Prints 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 the 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 critical, 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 the lowest rank.

.. option:: --unlink

With :option:`--write`, unlink all input files after the output
has been successfully created.

.. option:: --version

Displays program version and exits.

.. option:: --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 coverage data files (likely
generated from random test runs) into one master coverage file.

.. option:: --write-info <filename.info>

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

Converting from the Verilator coverage data format to the info format is
lossy; the info will have all forms of coverage merged line coverage, and
if there are multiple coverage points on a single line they will merge.
The minimum coverage across all merged points will be used to report
coverage of the line.