Fuzz testing: finding bugs in JIT compiler and much more

Stability and functional consistency are what Java machines’ users usually expect, along with the fast work of the code they’ve compiled. For this very purpose, there are compiler optimizations, but the more aggressive they improve the code, the more problems can sneak in. So how can we bring together such controversial goals as speed and consistency of the compiled code? Especially if your compiler is based on LLVM and tens of thousands of changed code lines are added to it every week? How to find hidden bugs before any user runs into one of them? In this talk I’ll share how we look for functional problems in the compiler of Zing Java machine, using automatic generator of test programs on Java.