Waterfall: Primitives Generation on the Fly

TL;DR

Waterfall is a dynamic translator that generates and executes primitives on demand, enabling runtime modification and customization of VM components in managed runtimes.

Contribution

We introduce Waterfall, a reflective translator that allows dynamic primitive generation and VM customization, overcoming static design limitations of traditional VMs.

Findings

Enables runtime modification of primitives.

Supports dynamic VM plug-in customization.

Demonstrates practical implementation with Slang to native code.

Abstract

Modern languages are typically supported by managed runtimes (Virtual Machines). Since VMs have to deal with many concepts such as memory management, abstract execution model and scheduling, they tend to be very complex. Additionally, VMs have to meet strong performance requirements. This demand of performance is one of the main reasons why many VMs are built statically. Thus, design decisions are frozen at compile time preventing changes at runtime. One clear example is the impossibility to dynamically adapt or change primitives of the VM once it has been compiled. In this work we present a toolchain that allows for altering and configuring components such as primitives and plug-ins at runtime. The main contribution is Waterfall, a dynamic and reflective translator from Slang, a restricted subset of Smalltalk, to native code. Waterfall generates primitives on demand and executes them on the fly. We validate our approach by implementing dynamic primitive modification and runtime customization of VM plug-ins.