RustHornBelt Library & Benchmarks

This crate contains the evaluation libraries and benchmarks for the RustHornBelt PLDI paper.

The crate includes the following benchmarks:

1. Fibonacci Cell, demonstrates how the RustHornBelt representation of Cells as invariants is expressive enough to express memoization by memoizing a fibonacci calculation.
2. Even Cell, demonstrates a simple invariant cell which always holds an even value.
3. In Place List reversal, reverses a linked list inplace using a memswap like function, proved correct in RustHornBelt.
4. Even Mutex, demonstrates how to use an invariant representation for a mutex by storing and incrementing an even value within one.
5. Knight's Tour, proves the safety of a Knight's Tour calculation, using specifications proved for vectors.
6. All Zero, zeroes the cells of a vector using indexing.
7. Inc Vec, increments the cells of a vector using a mutable iterator, proved correct in RustHornBelt.

Each example is in its own file inside of src/

All RustHornBelt specifications are provided in src/prelude/.

Brief overview of Creusot specification syntax.

Creusot specifications are written in a first-order program logic, which includes two novel operators. The ^ operator (pronounced final) accesses the prophecy of a mutable borrow, this corresponds to taking the second projection of the representation of a mutable borrow in RustHornBelt. The @ operator (pronounced model) accesses the representation value of a type, like ⌊_⌋ in RustHornBelt. To access the current value of a mutable borrow, we just use normal dereferencing, as it is just the value being pointed to at any moment by the borrow.

So the resolution of a mutable borrow can be expressed as the equality: ^ x == * x, stating that the final value of x equals the current value of x.

Generating and verifying proofs yourself

1. To verify the benchmarks, first install Creusot:

git clone https://github.com/xldenis/creusot
cargo install --path creusot

2. Install Why3, following Creusot's installation guide:

opam pin add why3 https://gitlab.inria.fr/why3/why3.git#master

3. Install Z3 and CVC4.

4. Configure why3:

why3 config detect

4. Then compile the crate using Creusot:

make proofs

5. Finally, load the proofs in why3

why3 ide -Lpath/to/creusot/prelude proofs.mlcfg