Add dependency on mach-dxcompiler-rs and support statically linking DXC

Author: DouglasDwyer

Cargo.lock

@@ -149,6 +149,7 @@ gpu-descriptor = "0.3"
 bit-set = "0.8"
 gpu-allocator = { version = "0.27", default-features = false }
 range-alloc = "0.1"
+mach-dxcompiler-rs = { version = "2023.12.14+0b7073b.1", default-features = false }
 windows-core = { version = "0.58", default-features = false }
 
 # Gles dependencies

Cargo.toml

@@ -91,6 +91,8 @@ dx12 = [
     "windows/Win32_System_Threading",
     "windows/Win32_UI_WindowsAndMessaging",
 ]
+## Enables the static DXC compiler using the `mach-dxcompiler-rs` crate.
+mach-dxcompiler-rs = [ "dep:mach-dxcompiler-rs" ]
 renderdoc = ["dep:libloading", "dep:renderdoc-sys"]
 fragile-send-sync-non-atomic-wasm = ["wgt/fragile-send-sync-non-atomic-wasm"]
 # Panic when running into an out-of-memory error (for debugging purposes).
@@ -158,6 +160,7 @@ windows = { workspace = true, optional = true }
 bit-set = { workspace = true, optional = true }
 range-alloc = { workspace = true, optional = true }
 gpu-allocator = { workspace = true, optional = true }
+mach-dxcompiler-rs = { workspace = true, optional = true }
 # For core macros. This crate is also reexported as windows::core.
 windows-core = { workspace = true, optional = true }
 

wgpu-hal/Cargo.toml

@@ -80,10 +80,22 @@ impl crate::Instance for super::Instance {
                 dxil_path,
                 dxc_path,
             } => {
-                let container = super::shader_compilation::get_dxc_container(dxc_path, dxil_path)
-                    .map_err(|e| {
-                    crate::InstanceError::with_source(String::from("Failed to load DXC"), e)
-                })?;
+                let container =
+                    super::shader_compilation::get_dynamic_dxc_container(dxc_path, dxil_path)
+                        .map_err(|e| {
+                            crate::InstanceError::with_source(String::from("Failed to load DXC"), e)
+                        })?;
+
+                container.map(Arc::new)
+            }
+            wgt::Dx12Compiler::MachDxc => {
+                let container =
+                    super::shader_compilation::get_mach_dxc_container().map_err(|e| {
+                        crate::InstanceError::with_source(
+                            String::from("Failed to load Mach DXC"),
+                            e,
+                        )
+                    })?;
 
                 container.map(Arc::new)
             }

wgpu-hal/src/dx12/instance.rs

@@ -78,6 +78,12 @@ pub(super) fn compile_fxc(
     }
 }
 
+type DxcCreateInstanceFn = unsafe extern "system" fn(
+    rclsid: *const windows_core::GUID,
+    riid: *const windows_core::GUID,
+    ppv: *mut *mut core::ffi::c_void,
+) -> windows_core::HRESULT;
+
 trait DxcObj: Interface {
     const CLSID: windows::core::GUID;
 }
@@ -97,7 +103,10 @@ struct DxcLib {
 }
 
 impl DxcLib {
-    fn new(lib_path: Option<PathBuf>, lib_name: &'static str) -> Result<Self, libloading::Error> {
+    fn new_dynamic(
+        lib_path: Option<PathBuf>,
+        lib_name: &'static str,
+    ) -> Result<Self, libloading::Error> {
         let lib_path = if let Some(lib_path) = lib_path {
             if lib_path.is_file() {
                 lib_path
@@ -111,15 +120,19 @@ impl DxcLib {
     }
 
     pub fn create_instance<T: DxcObj>(&self) -> Result<T, crate::DeviceError> {
-        type Fun = extern "system" fn(
-            rclsid: *const windows_core::GUID,
-            riid: *const windows_core::GUID,
-            ppv: *mut *mut core::ffi::c_void,
-        ) -> windows_core::HRESULT;
-        let func: libloading::Symbol<Fun> = unsafe { self.lib.get(b"DxcCreateInstance\0") }?;
+        unsafe {
+            let func: libloading::Symbol<DxcCreateInstanceFn> =
+                self.lib.get(b"DxcCreateInstance\0")?;
+            dxc_create_instance::<T>(*func)
+        }
+    }
+}
 
+/// Invokes the provided library function to create a DXC object.
+unsafe fn dxc_create_instance<T: DxcObj>(f: DxcCreateInstanceFn) -> Result<T, crate::DeviceError> {
+    unsafe {
         let mut result__ = None;
-        (func)(&T::CLSID, &T::IID, <*mut _>::cast(&mut result__))
+        f(&T::CLSID, &T::IID, <*mut _>::cast(&mut result__))
             .ok()
             .into_device_result("DxcCreateInstance")?;
         result__.ok_or(crate::DeviceError::Unexpected)
@@ -130,18 +143,20 @@ impl DxcLib {
 pub(super) struct DxcContainer {
     compiler: Dxc::IDxcCompiler3,
     utils: Dxc::IDxcUtils,
-    validator: Dxc::IDxcValidator,
+    validator: Option<Dxc::IDxcValidator>,
     // Has to be held onto for the lifetime of the device otherwise shaders will fail to compile.
-    _dxc: DxcLib,
+    // Only needed when using dynamic linking.
+    _dxc: Option<DxcLib>,
     // Also Has to be held onto for the lifetime of the device otherwise shaders will fail to validate.
-    _dxil: DxcLib,
+    // Only needed when using dynamic linking.
+    _dxil: Option<DxcLib>,
 }
 
-pub(super) fn get_dxc_container(
+pub(super) fn get_dynamic_dxc_container(
     dxc_path: Option<PathBuf>,
     dxil_path: Option<PathBuf>,
 ) -> Result<Option<DxcContainer>, crate::DeviceError> {
-    let dxc = match DxcLib::new(dxc_path, "dxcompiler.dll") {
+    let dxc = match DxcLib::new_dynamic(dxc_path, "dxcompiler.dll") {
         Ok(dxc) => dxc,
         Err(e) => {
             log::warn!(
@@ -153,7 +168,7 @@ pub(super) fn get_dxc_container(
         }
     };
 
-    let dxil = match DxcLib::new(dxil_path, "dxil.dll") {
+    let dxil = match DxcLib::new_dynamic(dxil_path, "dxil.dll") {
         Ok(dxil) => dxil,
         Err(e) => {
             log::warn!(
@@ -172,12 +187,37 @@ pub(super) fn get_dxc_container(
     Ok(Some(DxcContainer {
         compiler,
         utils,
-        validator,
-        _dxc: dxc,
-        _dxil: dxil,
+        validator: Some(validator),
+        _dxc: Some(dxc),
+        _dxil: Some(dxil),
     }))
 }
 
+/// Creates a [`DxcContainer`] that delegates to the statically-linked `mach-dxcompiler` library.
+pub(super) fn get_mach_dxc_container() -> Result<Option<DxcContainer>, crate::DeviceError> {
+    #[cfg(feature = "mach-dxcompiler-rs")]
+    {
+        unsafe {
+            let compiler =
+                dxc_create_instance::<Dxc::IDxcCompiler3>(mach_dxcompiler_rs::DxcCreateInstance)?;
+            let utils =
+                dxc_create_instance::<Dxc::IDxcUtils>(mach_dxcompiler_rs::DxcCreateInstance)?;
+
+            Ok(Some(DxcContainer {
+                compiler,
+                utils,
+                validator: None,
+                _dxc: None,
+                _dxil: None,
+            }))
+        }
+    }
+    #[cfg(not(feature = "mach-dxcompiler-rs"))]
+    {
+        panic!("Attempted to create a Mach DXC shader compiler, but the mach-dxcompiler-rs feature was not enabled")
+    }
+}
+
 /// Owned PCWSTR
 #[allow(clippy::upper_case_acronyms)]
 struct OPCWSTR {
@@ -288,26 +328,24 @@ pub(super) fn compile_dxc(
 
     let blob = get_output::<Dxc::IDxcBlob>(&compile_res, Dxc::DXC_OUT_OBJECT)?;
 
-    let err_blob = {
-        let res = unsafe {
-            dxc_container
-                .validator
-                .Validate(&blob, Dxc::DxcValidatorFlags_InPlaceEdit)
-        }
-        .into_device_result("Validate")?;
+    if let Some(validator) = &dxc_container.validator {
+        let err_blob = {
+            let res = unsafe { validator.Validate(&blob, Dxc::DxcValidatorFlags_InPlaceEdit) }
+                .into_device_result("Validate")?;
 
-        unsafe { res.GetErrorBuffer() }.into_device_result("GetErrorBuffer")?
-    };
+            unsafe { res.GetErrorBuffer() }.into_device_result("GetErrorBuffer")?
+        };
 
-    let size = unsafe { err_blob.GetBufferSize() };
-    if size != 0 {
-        let err_blob = unsafe { dxc_container.utils.GetBlobAsUtf8(&err_blob) }
-            .into_device_result("GetBlobAsUtf8")?;
-        let err = as_err_str(&err_blob)?;
-        return Err(crate::PipelineError::Linkage(
-            stage_bit,
-            format!("DXC validation error: {err}"),
-        ));
+        let size = unsafe { err_blob.GetBufferSize() };
+        if size != 0 {
+            let err_blob = unsafe { dxc_container.utils.GetBlobAsUtf8(&err_blob) }
+                .into_device_result("GetBlobAsUtf8")?;
+            let err = as_err_str(&err_blob)?;
+            return Err(crate::PipelineError::Linkage(
+                stage_bit,
+                format!("DXC validation error: {err}"),
+            ));
+        }
     }
 
     Ok(crate::dx12::CompiledShader::Dxc(blob))

wgpu-hal/src/dx12/shader_compilation.rs

@@ -7401,6 +7401,9 @@ pub enum Dx12Compiler {
         /// Path to the `dxcompiler.dll` file, or path to the directory containing `dxcompiler.dll` file. Passing `None` will use standard platform specific dll loading rules.
         dxc_path: Option<PathBuf>,
     },
+    /// The statically-linked variant of Dxc, sourced from the [`mach-dxcompiler-rs`](https://crates.io/crates/mach-dxcompiler-rs) crate.
+    /// The `mach-dxcompiler-rs` feature is required to use this.
+    MachDxc,
 }
 
 /// Selects which OpenGL ES 3 minor version to request.

wgpu-types/src/lib.rs

@@ -73,6 +73,9 @@ glsl = ["naga/glsl-in", "wgc/glsl"]
 ## Enable accepting WGSL shaders as input.
 wgsl = ["wgc?/wgsl"]
 
+## Enables the static DXC compiler using the `mach-dxcompiler-rs` crate.
+mach-dxcompiler-rs = ["hal/mach-dxcompiler-rs"]
+
 ## Enable accepting naga IR shaders as input.
 naga-ir = ["dep:naga"]