Commit Procedures¶

For external developers¶

For developers with commit rights¶

The guiding principle in internal development is to submit your work into the repository without breaking other people’s work. When you commit, make sure that the repository compiles, that the flow runs, and that you did not clobber someone else’s work. In the event that you are responsible for “breaking the build”, fix the build at top priority.

We have some guidelines in place to help catch most of these problems:

Before you push code to the central repository, your code MUST pass the check-in regression test. The check-in regression test is a quick way to test if any part of the VTR flow is broken.

At a minimum you must run:
```
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic
```
You may push if all the tests return All tests passed.

However you are strongly encouraged to run both the basic and strong regression tests:
```
#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic vtr_reg_strong
```
since it performs much more thorough testing.

It is typically a good idea to run tests regularily as you make changes. If you have failures see how to debugging failed tests.
The automated BuildBot will perform more extensive regressions tests and mark which revisions are stable.
Everyone who is doing development must write regression tests for major feature they create. This ensures regression testing will detect if a feature is broken by someone (or yourself). See Adding Tests for details.
In the event a regression test is broken, the one responsible for having the test pass is in charge of determining:
- If there is a bug in the source code, in which case the source code needs to be updated to fix the bug, or
- If there is a problem with the test (perhaps the quality of the tool did in fact get better or perhaps there is a bug with the test itself), in which case the test needs to be updated to reflect the new changes.
If the golden results need to be updated and you are sure that the new golden results are better, use the command ../scripts/parse_vtr_task.pl -create_golden your_regression_test_name_here
Keep in sync with the master branch as regularly as you can (i.e. git pull or git pull --rebase). The longer code deviates from the trunk, the more painful it is to integrate back into the trunk.

Whatever system that we come up with will not be foolproof so be conscientious about how your changes will effect other developers.

Running Tests¶

VTR has a variety of tests which are used to check for correctness, performance and Quality of Result (QoR).

There are 4 main regression tests:

vtr_reg_basic: ~3 minutes serial

Goal: Quickly check basic VTR flow correctness

Feature Coverage: Low

Benchmarks: A few small and simple circuits

Architectures: A few simple architectures

Not suitable for evaluating QoR or performance.
vtr_reg_strong: ~30 minutes serial, ~15 minutes with -j4

Goal: Exercise most of VTR’s features, moderately fast.

Feature Coverage: High

Benchmarks: A few small circuits, with some special benchmarks to exercise specific features

Architectures: A variety of architectures, including special architectures to exercise specific features

Not suitable for evaluating QoR or performance.
vtr_reg_nightly: ~15 hours with -j2

Goal: Basic QoR and Performance evaluation.

Feature Coverage: Medium

Benchmarks: Small-medium size, diverse. Includes:
- MCNC20 benchmarks
- VTR benchmarks
- Titan ‘other’ benchmarks (smaller than Titan23)
Architectures: A wider variety of architectures
vtr_reg_weekly: ~30 hours with -j2

Goal: Full QoR and Performance evaluation.

Feature Coverage: Medium

Benchmarks: Medium-Large size, diverse. Includes:
- VTR benchmarks
- Titan23 benchmarks
Architectures: A wide variety of architectures

These can be run with run_reg_test.pl:

#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_basic
$ ./run_reg_test.pl vtr_reg_strong

The nightly and weekly regressions require the Titan benchmarks which can be integrated into your VTR tree with:

make get_titan_benchmarks

They can then be run using run_reg_test.pl:

$ ./run_reg_test.pl vtr_reg_nightly
$ ./run_reg_test.pl vtr_reg_weekly

To speed-up things up, individual sub-tests can be run in parallel using the -j option:

#Run up to 4 tests in parallel
$ ./run_reg_test.pl vtr_reg_strong -j4

You can also run multiple regression tests together:

#Run both the basic and strong regression, with up to 4 tests in parallel
$ ./run_reg_test.pl vtr_reg_basic vtr_reg_strong -j4

Odin Functionality Tests¶

Odin has its own set of tests to verify the correctness of its synthesis results:

odin_reg_micro: ~2 minutes serial
odin_reg_full: ~6 minutes serial

These can be run with:

#From the VTR root directory
$ ./run_reg_test.pl odin_reg_micro
$ ./run_reg_test.pl odin_reg_full

and should be used when makeing changes to Odin.

Unit Tests¶

VTR also has a limited set of unit tests, which can be run with:

#From the VTR root directory
$ make && make test

Debugging Failed Tests¶

If a test fails you probably want to look at the log files to determine the cause.

Lets assume we have a failure in vtr_reg_basic:

#In the VTR root directory
$ ./run_reg_test.pl vtr_reg_strong
#Output trimmed...
regression_tests/vtr_reg_basic/basic_no_timing
-----------------------------------------
k4_N10_memSize16384_memData64/ch_intrinsics...failed: vpr
k4_N10_memSize16384_memData64/diffeq1...failed: vpr
#Output trimmed...
regression_tests/vtr_reg_basic/basic_no_timing...[Fail]
 k4_N10_memSize16384_memData64.xml/ch_intrinsics.v vpr_status: golden = success result = exited
#Output trimmed...
Error: 10 tests failed!

Here we can see that vpr failed, which caused subsequent QoR failures ([Fail]), and resulted in 10 total errors.

To see the log files we need to find the run directory. We can see from the output that the specific test which failed was regression_tests/vtr_reg_basic/basic_no_timing. All the regression tests take place under vtr_flow/tasks, so the test directory is vtr_flow/tasks/regression_tests/vtr_reg_basic/basic_no_timing. Lets move to that directory:

#From the VTR root directory
$ cd vtr_flow/tasks/regression_tests/vtr_reg_basic/basic_no_timing
$ ls
config  run002  run004
run001  run003  run005

There we see there is a config directory (which defines the test), and a set of run-directories. Each time a test is run it creates a new runXXX directory (where XXX is an incrementing number). From the above we can tell that our last run was run005. From the output of run_reg_test.pl we know that one of the failing architecture/circuit combinations was k4_N10_memSize16384_memData64/ch_intrinsics. Each architecture/circuit combination is run in its own sub-folder. Lets move to that directory:

$ cd run005/k4_N10_memSize16384_memData64/ch_intrinsics
$ ls
abc.out                     k4_N10_memSize16384_memData64.xml  qor_results.txt
ch_intrinsics.net           odin.out                           thread_1.out
ch_intrinsics.place         output.log                         vpr.out
ch_intrinsics.pre-vpr.blif  output.txt                         vpr_stdout.log
ch_intrinsics.route         parse_results.txt

Here we can see the individual log files produced by each tool (e.g. vpr.out), which we can use to guide our debugging. We could also manually re-run the tools (e.g. with a debugger) using files in this directory.

Adding Tests¶

Any time you add a feature to VTR you must add a test which exercies the feature. This ensures that regression tests will detect if the feature breaks in the future.

Consider which regression test suite your test should be added to (see Running Tests descriptions).

Typically, test which exercise new features should be added to vtr_reg_strong. These tests should use small benchmarks to ensure they:

run quickly (so they get run often!), and
are easier to debug. If your test will take more than ~2 mintues it should probably go in a longer running regression test (but see first if you can create a smaller testcase first).

Adding a test to vtr_reg_strong¶

This describes adding a test to vtr_reg_strong, but the process is similar for the other regression tests.

Create a configuration file

First move to the vtr_reg_strong directory:

#From the VTR root directory
$ cd vtr_flow/tasks/regression_tests/vtr_reg_strong
$ ls
qor_geomean.txt             strong_flyover_wires        strong_pack_and_place
strong_analysis_only        strong_fpu_hard_block_arch  strong_power
strong_bounding_box         strong_fracturable_luts     strong_route_only
strong_breadth_first        strong_func_formal_flow     strong_scale_delay_budgets
strong_constant_outputs     strong_func_formal_vpr      strong_sweep_constant_outputs
strong_custom_grid          strong_global_routing       strong_timing
strong_custom_pin_locs      strong_manual_annealing     strong_titan
strong_custom_switch_block  strong_mcnc                 strong_valgrind
strong_echo_files           strong_minimax_budgets      strong_verify_rr_graph
strong_fc_abs               strong_multiclock           task_list.txt
strong_fix_pins_pad_file    strong_no_timing            task_summary
strong_fix_pins_random      strong_pack

Each folder (prefixed with strong_ in this case) defines a task (sub-test).

Let’s make a new task named strong_mytest. An easy way is to copy an existing configuration file such as strong_timing/config/config.txt

$ mkdir -p strong_mytest/config
$ cp strong_timing/config/config.txt strong_mytest/config/.

You can now edit strong_mytest/config/config.txt to customize your test.

Generate golden reference results

Now we need to test our new test and generate ‘golden’ reference results. These will be used to compare future runs of our test to detect any changes in behaviour (e.g. bugs).

From the VTR root, we move to the vtr_flow/tasks directory, and then run our new test:

#From the VTR root
$ cd vtr_flow/tasks
$ ../scripts/run_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest

regression_tests/vtr_reg_strong/strong_mytest
-----------------------------------------
Current time: Jan-25 06:51 PM.  Expected runtime of next benchmark: Unknown
k6_frac_N10_mem32K_40nm/ch_intrinsics...OK

Next we can generate the golden reference results using parse_vtr_task.pl with the -create_golden option:

$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest -create_golden

And check that everything matches with -check_golden:

$ ../scripts/parse_vtr_task.pl regression_tests/vtr_reg_strong/strong_mytest -check_golden
regression_tests/vtr_reg_strong/strong_mytest...[Pass]

Add it to the task list

We now need to add our new strong_mytest task to the task list, so it is run whenever vtr_reg_strong is run. We do this by adding the line regression_tests/vtr_reg_strong/strong_mytest to the end of vtr_reg_strong’s task_list.txt:

#From the VTR root directory
$ vim vtr_flow/tasks/regression_tests/vtr_reg_strong/task_list.txt
# Add a new line 'regression_tests/vtr_reg_strong/strong_mytest' to the end of the file

Now, when we run vtr_reg_strong:

#From the VTR root directory
$ ./run_reg_test.pl vtr_reg_strong
#Output trimmed...
regression_tests/vtr_reg_strong/strong_mytest
-----------------------------------------
#Output trimmed...

we see our test is run.

Commit the new test

Finally you need to commit your test:

#Add the config.txt and golden_results.txt for the test
$ git add vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_mytest/
#Add the change to the task_list.txt
$ git add vtr_flow/tasks/regression_tests/vtr_reg_strong/task_list.txt
#Commit the changes, when pushed the test will automatically be picked up by BuildBot
$ git commit

Debugging Aids¶

VTR has support for several additional tools/features to aid debugging.

Sanitizers¶

VTR can be compiled using sanitizers which will detect invalid memory accesses, memory leaks and undefined behaviour (supported by both GCC and LLVM):

#From the VTR root directory
$ cmake -D VTR_ENABLE_SANITIZE=ON build
$ make

Assertion Levels¶

VTR supports configurable assertion levels.

The default level (2) which turns on most assertions which don’t cause significant run-time penalties.

This level can be increased:

#From the VTR root directory
$ cmake -D VTR_ASSERT_LEVEL=3 build
$ make

this turns on more extensive assertion checking and re-builds VTR.

External Subtrees¶

VTR includes some code which is developed in external repositories, and is integrated into the VTR source tree using git subtrees.

To simplify the process of working with subtrees we use the dev/update_external_subtrees.py script.

For instance, running ./dev/update_external_subtrees.py --list from the VTR root it shows the subtrees:

Component: abc             Path: abc                            URL: https://github.com/berkeley-abc/abc.git       URL_Ref: master
Component: libargparse     Path: libs/EXTERNAL/libargparse      URL: https://github.com/kmurray/libargparse.git    URL_Ref: master
Component: libblifparse    Path: libs/EXTERNAL/libblifparse     URL: https://github.com/kmurray/libblifparse.git   URL_Ref: master
Component: libsdcparse     Path: libs/EXTERNAL/libsdcparse      URL: https://github.com/kmurray/libsdcparse.git    URL_Ref: master
Component: libtatum        Path: libs/EXTERNAL/libtatum         URL: https://github.com/kmurray/tatum.git          URL_Ref: master

Code included in VTR by subtrees should not be modified within the VTR source tree. Instead changes should be made in the relevant up-stream repository, and then synced into the VTR tree.

Updating an existing Subtree¶

From the VTR root run: ./dev/external_subtrees.py $SUBTREE_NAME, where $SUBTREE_NAME is the name of an existing subtree.

For example to update the libtatum subtree:
```
./dev/external_subtrees.py --update libtatum
```

Adding a new Subtree¶

To add a new external subtree to VTR do the following:

Add the subtree specification to dev/subtree_config.xml.

For example to add a subtree name libfoo from the master branch of https://github.com/kmurray/libfoo.git to libs/EXTERNAL/libfoo you would add:

<subtree 
    name="libfoo"
    internal_path="libs/EXTERNAL/libfoo"
    external_url="https://github.com/kmurray/libfoo.git"
    default_external_ref="master"/>

within the existing <subtrees> tag.

Note that the internal_path directory should not already exist.

You can confirm it works by running: def/external_subtrees.py --list:

Component: abc             Path: abc                            URL: https://github.com/berkeley-abc/abc.git       URL_Ref: master
Component: libargparse     Path: libs/EXTERNAL/libargparse      URL: https://github.com/kmurray/libargparse.git    URL_Ref: master
Component: libblifparse    Path: libs/EXTERNAL/libblifparse     URL: https://github.com/kmurray/libblifparse.git   URL_Ref: master
Component: libsdcparse     Path: libs/EXTERNAL/libsdcparse      URL: https://github.com/kmurray/libsdcparse.git    URL_Ref: master
Component: libtatum        Path: libs/EXTERNAL/libtatum         URL: https://github.com/kmurray/tatum.git          URL_Ref: master
Component: libfoo          Path: libs/EXTERNAL/libfoo           URL: https://github.com/kmurray/libfoo.git         URL_Ref: master

which shows libfoo is now recognized.

Run ./dev/update_external_subtrees.py $SUBTREE_NAME to add the subtree.

For the libfoo example above this would be:
```
./dev/update_external_subtrees.py libfoo
```
This will create two commits to the repository. The first will squash all the upstream changes, the second will merge those changes into the current branch.

Subtree Rational¶

VTR uses subtrees to allow easy tracking of upstream dependencies.

Their main advantages included:

Works out-of-the-box: no actions needed post checkout to pull in dependencies (e.g. no git submodule update --init --recursive)
Simplified upstream version tracking
Potential for local changes (although in VTR we do not use this to make keeping in sync easier)

See here for a more detailed discussion.

Finding Bugs with Coverity¶

Coverity Scan is a static code analysis service which can be used to detect bugs.

Browsing Defects¶

To view defects detected do the following:

Get a coverity scan account

Contact a project maintainer for an invitation.
Browse the existing defects through the coverity web interface

Submitting a build¶

To submit a build to coverity do the following:

Download the coverity build tool
Configure VTR to perform a debug build. This ensures that all assertions are enabled, without assertions coverity may report bugs that are gaurded against by assertions. We also set VTR asserts to the highest level.
```
#From the VTR root
mkdir -p build
cd build
CC=gcc CXX=g++ cmake -DCMAKE_BUILD_TYPE=debug -DVTR_ASSERT_LEVEL=3 ..
```

Note that we explicitly asked for gcc and g++, the coverity build tool defaults to these compilers, and may not like the default ‘cc’ or ‘c++’ (even if they are linked to gcc/g++).

Run the coverity build tool

#From the build directory where we ran cmake
cov-build --dir cov-int make -j8

Archive the output directory
```
tar -czvf vtr_coverity.tar.gz cov-int
```
Submit the archive through the coverity web interface

Once the build has been analyzed you can browse the latest results throught the coverity web interface

No files emitted¶

If you get the following warning from cov-build:

[WARNING] No files were emitted.

You may need to configure coverity to ‘know’ about your compiler. For example:

```shell
cov-configure --compiler `which gcc-7`
```

On unix-like systems run scan-build make from the root VTR directory. to output the html analysis to a specific folder, run scan-build make -o /some/folder

Debugging with clang static analyser¶

First make sure you have clang installed. define clang as the default compiler: export CC=clang export CXX=clang++

set the build type to debug in makefile