Inside VOLT: Designing an Open-Source GPU Compiler (arxiv.org)

Researchers introduced VOLT (Vortex-Optimized Lightweight Toolchain), an open-source GPU compiler framework designed to bridge existing GPU software and emerging open-GPU ISAs that implement SIMT (single-instruction-multiple-thread) semantics. The paper lays out VOLT’s design principles and overall architecture and argues that compiler infrastructure—often overlooked in open-hardware projects—is crucial for executing and optimizing legacy GPU programs on new ISAs. By providing a reusable, extensible toolchain, VOLT aims to lower the engineering cost and friction that currently slow adoption of open GPU architectures. Technically, VOLT uses a hierarchical design that separates concerns across front-ends, a centralized middle-end, and back-ends, enabling SIMT code generation and optimizations at multiple abstraction levels. Key innovations include centralized SIMT analyses and transformations in the middle-end so they can be shared across diverse front-end languages and mapped to different Vortex ISA variants. The paper validates the approach with case studies showing how VOLT handles ISA extensions and host–runtime API changes, demonstrating easier adaptation and performance tuning for new open-GPU designs. For the AI/ML community, VOLT promises more portable GPU software, faster experimentation on novel hardware, and a clearer path to performance parity with vendor toolchains.