DirectX Adopting SPIR-V as the Interchange Format of the Future

Original Article ↗ Hacker News Discussion ↗

HLSL, GLSL, Slang, and SPIR-V Direction

  • HLSL is described as the de facto language for both DirectX and much of Vulkan; GLSL is seen as legacy.
  • Khronos has reportedly stated GLSL will not get major new work; it lacks modern language features and modularity.
  • HLSL is evolving (C++-like features, templates, mesh shaders, work graphs, modules).
  • Some hope Nvidia’s Slang might become a Khronos-standard high-level language, but it’s unclear.

Impact on Proton/Linux Gaming

  • If DirectX starts emitting SPIR-V instead of DXIL, translating shaders for Proton/Wine should become easier.
  • Current DXIL→SPIR-V conversion is described as extremely painful; much of that complexity would vanish with native SPIR-V.
  • There is mild concern about a potentially incompatible “DirectX-flavored” SPIR-V, but others consider divergence unlikely at the core level.

WebGPU, WGSL, and Apple/Khronos Tensions

  • Many note industry participants originally wanted SPIR-V or HLSL for WebGPU, not a new language.
  • WGSL is portrayed by several as a political compromise driven largely by Apple’s refusal to accept Khronos IP/SPIR-V, with formal meeting minutes cited.
  • Some find WGSL syntactically unpleasant and a barrier to adoption; others appreciate its simplicity and clear spec.
  • Native WebGPU backends typically use SPIR-V; browsers require WGSL, forcing costly SPIR-V↔WGSL conversions that some see as wasted effort.

Future of GLSL and Khronos Strategy

  • GLSL is expected to receive only maintenance and vendor extensions, no major specs.
  • Khronos reportedly lacks budget and language-design expertise; higher-level language choice is effectively pushed to the community.

DirectX vs. Vulkan on Windows

  • Vulkan is considered a first-class option via vendor drivers, but not as deeply integrated into Windows as DirectX (no built-in loader, no WARP-like software path).
  • Some argue replacing D3D12 with Vulkan would be harmful: Vulkan’s broader scope (including mobile) complicates design, and D3D12 can evolve faster through private IHV–Microsoft collaboration.
  • Others counter that multiple APIs increase developer burden and lock-in; Vulkan is valued as the open, cross-platform option.

API and Spec Quality

  • Opinions diverge: some say D3D11/12 and Metal are better designed and more practical than OpenGL/Vulkan; others praise Vulkan’s consistency and documentation.
  • DirectX “engineering specs” are lauded as readable and implementation-aware, but criticized for being incomplete and under-specified in some areas.
  • Vulkan/SPIR-V specs aim to be comprehensive formal contracts, though they are acknowledged as imperfect and sometimes hard to interpret.

SPIR-V Dialects and Tooling Fragmentation

  • Participants note existing fragmentation: SPIR-V for Vulkan vs OpenCL already can’t share compilers cleanly.
  • There is concern that a DirectX SPIR-V dialect may worsen this, limiting the hoped-for “unified IR” benefits.
  • Some suggest the real blocker is organizational/ecosystem misalignment rather than technical impossibility.
  • One view is that DirectX’s move to SPIR-V mainly lets Microsoft retire an old LLVM-based DXIL stack in favor of a better-specified bytecode.