Add shader validation tests on subgroup-size-control - Part I (#4641)

* Add shader validation tests on `subgroup-size-control` - Part I

This patch adds the first part of the shader validation tests on
the extension `subgroup-size-control`:
- Enabling `subgroup_size_control` must also enable `subgroups`.
- The WGSL attribute `@subgroup_size` must be used when
  `subgroup_size_control` is enabled.
- `@subgroup_size` can only be used in the compute stage

issue: #4640

* Fix comments

* Address reviewer's comments

src/webgpu/shader/validation/extension/subgroup_size_control.spec.ts

@@ -0,0 +1,103 @@
+export const description = `
+Validation tests for the subgroup_size_control extension
+`;
+
+import { makeTestGroup } from '../../../../common/framework/test_group.js';
+import { UniqueFeaturesAndLimitsShaderValidationTest } from '../shader_validation_test.js';
+
+export const g = makeTestGroup(UniqueFeaturesAndLimitsShaderValidationTest);
+
+g.test('enable_subgroup_size_control_requires_subgroups')
+  .desc(
+    `Checks that enabling the WGSL extension subgroup_size_control without also enabling the
+     subgroups extension is a compilation error.`
+  )
+  .params(u => u.combine('enableSubgroups', [false, true] as const))
+  .beforeAllSubcases(t => {
+    t.selectDeviceOrSkipTestCase({
+      requiredFeatures: ['subgroup-size-control' as GPUFeatureName],
+    });
+  })
+  .fn(t => {
+    const { enableSubgroups } = t.params;
+
+    t.expectCompileResult(
+      enableSubgroups,
+      `
+        ${enableSubgroups ? 'enable subgroups;' : ''}
+        enable subgroup_size_control;
+        @compute @workgroup_size(1)
+        fn main() {}
+      `
+    );
+  });
+
+g.test('use_subgroup_size_attribute_requires_subgroup_size_control_extension_enabled')
+  .desc(
+    `Checks that the @subgroup_size attribute is only allowed with the WGSL extension
+     subgroup_size_control enabled in the shader and the WebGPU extension subgroup-size-control
+     supported on the device.`
+  )
+  .params(u => u.combine('enableExtension', [false, true] as const))
+  .beforeAllSubcases(t => {
+    t.selectDeviceOrSkipTestCase({
+      requiredFeatures: ['subgroup-size-control' as GPUFeatureName],
+    });
+  })
+  .fn(t => {
+    const { enableExtension } = t.params;
+
+    const kSubgroupSize = 4;
+    t.expectCompileResult(
+      enableExtension,
+      `
+        enable subgroups;
+        ${enableExtension ? 'enable subgroup_size_control;' : ''}
+        @compute @workgroup_size(${kSubgroupSize}) @subgroup_size(${kSubgroupSize})
+        fn main() {}
+      `
+    );
+  });
+
+g.test('subgroup_size_attribute_only_valid_in_compute_stage')
+  .desc(
+    `Checks that the @subgroup_size attribute is only valid on a compute shader entry point.
+     Applying it to a vertex or fragment entry point must be a compilation error.`
+  )
+  .params(u => u.combine('stage', ['compute', 'vertex', 'fragment'] as const))
+  .beforeAllSubcases(t => {
+    t.selectDeviceOrSkipTestCase({
+      requiredFeatures: ['subgroup-size-control' as GPUFeatureName],
+    });
+  })
+  .fn(t => {
+    const { stage } = t.params;
+    const kSubgroupSize = 4;
+
+    const kStageShaders = {
+      compute: `
+    enable subgroups;
+    enable subgroup_size_control;
+    @compute @workgroup_size(${kSubgroupSize}) @subgroup_size(${kSubgroupSize})
+    fn main() {}
+  `,
+      vertex: `
+    enable subgroups;
+    enable subgroup_size_control;
+    @vertex @subgroup_size(${kSubgroupSize})
+    fn main() -> @builtin(position) vec4f {
+      return vec4f(0);
+    }
+  `,
+      fragment: `
+    enable subgroups;
+    enable subgroup_size_control;
+    @fragment @subgroup_size(${kSubgroupSize})
+    fn main() -> @location(0) vec4f {
+      return vec4f(0);
+    }
+  `,
+    } as const;
+
+    t.expectCompileResult(stage === 'compute', kStageShaders[stage]);
+  });