Fix dx12 shader validation errors when dxil.dll isn't available in the local scope.

CHANGELOG.md

@@ -52,6 +52,10 @@ Bottom level categories:
 
 ### Bug Fixes
 
+#### DX12
+
+- Fix DXC validation issues when using a custom `dxil_path`. By @Elabajaba in [#3434](https://github.com/gfx-rs/wgpu/pull/3434)
+
 #### General
 
 - `copyTextureToTexture` src/dst aspects must both refer to all aspects of src/dst format. By @teoxoy in [#3431](https://github.com/gfx-rs/wgpu/pull/3431)

wgpu-hal/src/dx12/shader_compilation.rs

@@ -83,26 +83,33 @@ pub(super) fn compile_fxc(
 mod dxc {
  use std::path::PathBuf;
 
+ // Destructor order should be fine since _dxil and _dxc don't rely on each other.
  pub(crate) struct DxcContainer {
- pub compiler: hassle_rs::DxcCompiler,
- pub library: hassle_rs::DxcLibrary,
- // Has to be held onto for the lifetime of the device otherwise shaders will fail to compile
+ compiler: hassle_rs::DxcCompiler,
+ library: hassle_rs::DxcLibrary,
+ validator: hassle_rs::DxcValidator,
+ // Has to be held onto for the lifetime of the device otherwise shaders will fail to compile.
  _dxc: hassle_rs::Dxc,
+ // Also Has to be held onto for the lifetime of the device otherwise shaders will fail to validate.
+ _dxil: hassle_rs::Dxil,
  }
 
  pub(crate) fn get_dxc_container(
  dxc_path: Option<PathBuf>,
  dxil_path: Option<PathBuf>,
  ) -> Result<Option<DxcContainer>, crate::DeviceError> {
  // Make sure that dxil.dll exists.
- match hassle_rs::Dxil::new(dxil_path) {
- Ok(_) => (),
+ let dxil = match hassle_rs::Dxil::new(dxil_path) {
+ Ok(dxil) => dxil,
  Err(e) => {
  log::warn!("Failed to load dxil.dll. Defaulting to Fxc instead: {}", e);
  return Ok(None);
  }
  };
 
+ // Needed for explicit validation.
+ let validator = dxil.create_validator()?;
+
  let dxc = match hassle_rs::Dxc::new(dxc_path) {
  Ok(dxc) => dxc,
  Err(e) => {
@@ -113,13 +120,15 @@ mod dxc {
  return Ok(None);
  }
  };
- let dxc_compiler = dxc.create_compiler()?;
- let dxc_library = dxc.create_library()?;
+ let compiler = dxc.create_compiler()?;
+ let library = dxc.create_library()?;
 
  Ok(Some(DxcContainer {
  _dxc: dxc,
- compiler: dxc_compiler,
- library: dxc_library,
+ compiler,
+ library,
+ _dxil: dxil,
+ validator,
  }))
  }
 
@@ -136,8 +145,9 @@ mod dxc {
  log::Level,
  ) {
  profiling::scope!("compile_dxc");
- let mut compile_flags = arrayvec::ArrayVec::<&str, 3>::new_const();
+ let mut compile_flags = arrayvec::ArrayVec::<&str, 4>::new_const();
  compile_flags.push("-Ges"); // d3dcompiler::D3DCOMPILE_ENABLE_STRICTNESS
+ compile_flags.push("-Vd"); // Disable implicit validation to work around bugs when dxil.dll isn't in the local directory.
  if device
  .private_caps
  .instance_flags
@@ -156,7 +166,6 @@ mod dxc {
  Err(e) => return (Err(e), log::Level::Error),
  };
 
- // DXC will automatically validate the shaders during compilation as long as dxil.dll is available, so we don't need to do it ourselves.
  let compiled = dxc_container.compiler.compile(
  &blob,
  source_name,
@@ -169,10 +178,22 @@ mod dxc {
 
  let (result, log_level) = match compiled {
  Ok(dxc_result) => match dxc_result.get_result() {
- Ok(dxc_blob) => (
- Ok(crate::dx12::CompiledShader::Dxc(dxc_blob.to_vec())),
- log::Level::Info,
- ),
+ Ok(dxc_blob) => {
+ // Validate the shader.
+ match dxc_container.validator.validate(dxc_blob) {
+ Ok(validated_blob) => (
+ Ok(crate::dx12::CompiledShader::Dxc(validated_blob.to_vec())),
+ log::Level::Info,
+ ),
+ Err(e) => (
+ Err(crate::PipelineError::Linkage(
+ stage_bit,
+ format!("DXC validation error: {:?}\n{:?}", e.0, e.1),
+ )),
+ log::Level::Error,
+ ),
+ }
+ }
  Err(e) => (
  Err(crate::PipelineError::Linkage(
  stage_bit,