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

Original Article ↗ Hacker News Discussion ↗

Microsoft’s move to adopt SPIR-V as the intermediate format for DirectX shaders is seen as aligning PC graphics more closely with Vulkan and potentially easing compatibility layers like Proton on Linux. Commenters note that HLSL has effectively displaced GLSL as the industry’s main shading language, while Khronos shifts focus from GLSL to SPIR-V and Nvidia pushes Slang as a possible standard. Others highlight fragmentation risks (different SPIR-V “flavors”), WebGPU’s separate WGSL path driven in part by Apple’s refusal to use SPIR-V, and the broader tension between proprietary APIs like DirectX and open standards like Vulkan.

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.