FastSMT

FastSMT is a tool to augment your SMT solver by learning to optimize its performance for your dataset of formulas. Our tool is built on top of Z3 SMT solver (https://github.com/Z3Prover/z3). Currently we support Z3 4.6.2 and the tool is tested on Ubuntu 16.04.

Website

Website of the project is available at fastsmt.ethz.ch

Setup Instructions

Clone this repository

$ git clone https://github.com/eth-sri/fastsmt.git
$ cd fastsmt

Download Z3 4.6.2

$ git clone https://github.com/Z3Prover/z3.git z3
$ cd z3

# Checkout Z3 version 4.6.2 that we tested against
$ git checkout 5651d00751a1eb40b94db86f00cb7d3ec9711c4d 

Install and compile Z3 4.6.2 (with cpp bindings):

$ python scripts/mk_make.py 
$ cd build
$ make # (optional) use `make -j4` where 4 is the number of threads used to compile Z3, will likely take couple of minutes
$ sudo make install
$ cd ../..

Setup python virtual environment. The code is tested with python version 3.5:

$ virtualenv -p python3 --system-site-packages venv
$ source venv/bin/activate
(venv) $ python setup.py install

Install and compile Z3 4.6.2 (with Python bindings):

(venv) $ cd z3
# To generate correct python bindings make sure you activated the virtual env before Z3 compilation
(venv) $ python scripts/mk_make.py --python
(venv) $ cd build
(venv) $ make # (optional) use `make -j4` where 4 is the number of threads used to compile Z3, will likely take couple of minutes
(venv) $ sudo make install
(venv) $ cd ../..

Finally, compile C++ runner:

$ cd fastsmt/cpp
$ make -f make_z3_4.6.2
$ cd ..

Please run the tests to make sure installation was successful:

$ ./test/run_tests.sh
OK!

Creating the dataset

In this section we describe how to prepare the data for synthesis procedure. Our running example will be leipzig formulas (QF_NIA theory) from SMT-LIB benchmarks. First, download the formulas into examples subdirectory.

$ mkdir examples
$ cd examples
$ wget http://smt-lib.loria.fr/zip/QF_NIA.zip
$ unzip QF_NIA.zip
$ mkdir QF_NIA/leipzig/all
$ mv QF_NIA/leipzig/*.smt2 QF_NIA/leipzig/all/
$ cd ..

You should always create all subdirectory in which you should put all of the formulas in SMT2-LIB format. If you want to split your dataset into training/validation/test set in the ratio 50/20/30 then you use the following command:

(venv) $ python scripts/py/dataset_create.py --split "50 20 30" --benchmark_dir examples/QF_NIA/leipzig

In subfolders examples/QF_NIA/leipzig/train, examples/QF_NIA/leipzig/valid, examples/QF_NIA/leipzig/test you can find formulas which belong to training, validation and test set.

Learning and synthesis

Synthesis script performs search over the space of possible strategies and tries to synthesize best strategy for each instance. It receives configuration for the synthesis procedure, benchmark directory and other information.

Help menu with information about all possible arguments can be accessed with:

(venv) $ python synthesis/learning.py -h

In this toy example, we are going to load formulas from leipzig benchmark and run our procedure to synthesize best strategy for every formula. Concretely, we will first search randomly for 5 iterations, then train the neural network model and search for 5 more iterations (this time guided by the model). Here is an example of the full command (execution should take few minutes):

(venv) $ python synthesis/learning.py experiments/configs/leipzig/config_apprentice.json \
                --benchmark_dir examples/QF_NIA/leipzig/ \
                --max_timeout 10 \
                --num_iters 5 \
                --iters_inc 5 \
                --pop_size 1 \
                --eval_dir eval/synthesis/ \
                --smt_batch_size 100 \
                --full_pass 2 \
                --num_threads 10 \
                --experiment_name leipzig_example

Learned strategies are saved in directory given as eval_dir. As a guideline for setting the parameters of the learning procedure, we suggest to look at our experiments in the experiments subfolder.

Now, best strategies are saved in eval/synthesis/leipzig_example/train/2/strategies.txt. For the sake of this experiment, to see the results faster, we will sample only 10 strategies from the list of best strategies:

cat eval/synthesis/leipzig_example/train/2/strategies.txt | shuf | head -10 > sample_strategies.txt

You can also use eval/synthesis/leipzig_example/train/2/strategies.txt instead of sample_strategies.txt in the following command, but be prepared to wait more. Next, we are going to synthesize a final strategy in SMT2 format from these 10 learned strategies (running the script should take some time):

(venv) $ python synthesis/multi/multi_synthesis.py \
         --cache cache_leipzig_multi.txt \
         --max_timeout 10 \
         --benchmark_dir examples/QF_NIA/leipzig/ \
         --num_threads 10 \
         --strategy_file output_strategy.txt \
         --leaf_size 4 \
         --num_strategies 5 \
         --input_file sample_strategies.txt

After this command is finished you can find the synthesized strategy in SMT2 format in file output_strategy.txt. This strategy can be passed to Z3 solver as explained in: https://rise4fun.com/z3/tutorial/strategies

Validation

In order to evaluate final strategy synthesized by our system we provide a validation script. For an input, this script receives dataset with SMT2 formulas and a strategy. It runs Z3 solver with and without using given strategy and outputs the performance comparison (in terms of number of solved formulas and runtime).

(venv) $ python scripts/py/validate.py \
        --strategy_file output_strategy.txt \
        --benchmark_dir examples/QF_NIA/leipzig/test \
        --max_timeout 10 \
        --batch_size 4

Additional information

In order to reproduce experimental results from our paper, consult README file in fastsmt/experiments subfolder. For more details on the configuration of our system, consult README in fastsmt/experiments/configs.

Tensorboard integration

We use TensorboardX (https://github.com/lanpa/tensorboardX) to provide integration with Tensorboard. In order to inspect the training process of neural network model, you can run Tensorboard server with (where we assume Tensorboard saves data in runs/ folder):

(venv) $ tensorboard --logdir runs/

You can view the plots at: http://127.0.0.1:6006 where 6006 is the default port to which Tensorboard is logging the data.

Citing this work

@incollection{NIPS2018_8233,
  title = {Learning to Solve SMT Formulas},
  author = {Balunovic, Mislav and Bielik, Pavol and Vechev, Martin},
  booktitle = {Advances in Neural Information Processing Systems 31},
  editor = {S. Bengio and H. Wallach and H. Larochelle and K. Grauman and N. Cesa-Bianchi and R. Garnett},
  pages = {10337--10348},
  year = {2018},
  publisher = {Curran Associates, Inc.},
  url = {http://papers.nips.cc/paper/8233-learning-to-solve-smt-formulas.pdf}
}

Contributors

• Mislav Balunović - [email protected]
• Pavol Bielik - [email protected]
• Martin Vechev - [email protected]

License and Copyright

• Copyright (c) 2018 Secure, Reliable, and Intelligent Systems Lab (SRI), ETH Zurich
• Licensed under the Apache License