Spirv shader, update comment

tracel-ai · Nov 22, 2024 · c5f4ad4 · c5f4ad4
1 parent ec06010
commit c5f4ad4
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Showing 2 changed files with 17 additions and 20 deletions.
diff --git a/crates/cubecl-wgpu/src/compiler/spirv.rs b/crates/cubecl-wgpu/src/compiler/spirv.rs
@@ -102,23 +102,20 @@ impl WgpuCompiler for SpirvCompiler<GLCompute> {
             })
             .unwrap_or_else(|| {
                 let source = &kernel.source;
-                let module = match mode {
-                    ExecutionMode::Checked => {
-                        server
-                            .device
-                            .create_shader_module(wgpu::ShaderModuleDescriptor {
-                                label: None,
-                                source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(source)),
-                            })
-                    }
-                    ExecutionMode::Unchecked => unsafe {
-                        server
-                            .device
-                            .create_shader_module_unchecked(wgpu::ShaderModuleDescriptor {
-                                label: None,
-                                source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(source)),
-                            })
-                    },
+                // Cube always in principle uses unchecked modules. Certain operations like
+                // indexing are instead checked by cube. The WebGPU specification only makes
+                // incredibly loose gaurantees that Cube can't rely on. Additionally, kernels
+                // can opt in/out per operation whether checks should be performed which can be faster.
+                //
+                // SAFETY: Cube gaurantees OOB safety when launching in checked mode. Launching in unchecked mode
+                // is only availble through the use of unsafe code.
+                let module = unsafe {
+                    server
+                        .device
+                        .create_shader_module_unchecked(wgpu::ShaderModuleDescriptor {
+                            label: None,
+                            source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(source)),
+                        })
                 };
                 (module, None)
             });

diff --git a/crates/cubecl-wgpu/src/compiler/wgsl/instructions.rs b/crates/cubecl-wgpu/src/compiler/wgsl/instructions.rs
@@ -1066,9 +1066,9 @@ fn index(
     if let Some(ind) = index {
         if let Some(len) = len {
             // Note: This is technically not 100% allowed. According to the WebGPU specification,
-            // indexing OOB is a "dynamic error" which allows "many possible outcomes". In practice,
-            // both wgpu and Dawn handle this by either returning 0s or clamping the index
-            // to valid bounds. In practice this means it's harmless to use in a select.
+            // any OOB access is a "dynamic error" which allows "many possible outcomes". In practice,
+            // both wgpu and Dawn handle this by either returning dummy data or clamping the index
+            // to valid bounds. This means it's harmless to use in a select.
             let out_item = out.item();
             value = format!("select({out_item}(0), {value}, {ind} < {len})");
         };