Practical Validation of Bytecode to Bytecode JIT Compiler Dynamic Deoptimization

By: Clément Béra, Eliot Miranda, Marcus Denker, Stéphane Ducasse

Abstract

Speculative inlining in just-in-time compilers enables many performance optimizations. However, it also introduces significant complexity. The compiler optimizations themselves, as well as the deoptimization mechanism are complex and error prone. To stabilize our bytecode to bytecode just-in-time compiler, we designed a new approach to validate the correctness of dynamic deoptimization. The approach consists of the symbolic execution of an optimized and an unoptimized bytecode compiled method side by side, deoptimizing the abstract stack at each deoptimization point (where dynamic deoptimization is possible) and comparing the deoptimized and unoptimized abstract stack to detect bugs. The implementation of our approach generated tests for several hundred thousands of methods, which are now available to be run automatically after each commit.

Keywords

VMs, bytecode, JIT compilation

Cite as:

Clément Béra, Eliot Miranda, Marcus Denker, Stéphane Ducasse, “Practical Validation of Bytecode to Bytecode JIT Compiler Dynamic Deoptimization”, Journal of Object Technology, Volume 15, no. 2 (March 2016), pp. 1:1-26, doi:10.5381/jot.2016.15.2.a1.