Formal Verification of Just-in-Time Compilation

Just-in-Time compilation is a technique to execute programs, where execution is interleaved with optimizations.
Just-in-Time compilers often produce fast executions, but are particularly complex.
For instance, they reuse various existing techniques: some contain both interpreters to execute programs and traditional compilers to generate optimized machine code.
They also use ad hoc techniques like speculation, which consists in predicting the future behavior of the program to generate specialized code that executes particularly fast if the prediction holds.
This great complexity can lead to bugs.

This thesis tackles their formal verification, to develop Just-in-Time compilers in such a way that one can formally prove that they behave as prescribed by the semantics of the program they execute.
We present correctness proofs for their main features, including speculation, dynamic optimizations and machine code generation.
We reuse proof techniques from formally verified traditional compilers like CompCert.
All our proofs have been mechanized in the Coq proof assistant.