| // Copyright 2018 The Dawn Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "common/Constants.h" |
| |
| #include "dawn_native/ShaderModule.h" |
| |
| #include "tests/unittests/validation/ValidationTest.h" |
| |
| #include "utils/WGPUHelpers.h" |
| |
| #include <sstream> |
| |
| class ShaderModuleValidationTest : public ValidationTest {}; |
| |
| // Test case with a simpler shader that should successfully be created |
| TEST_F(ShaderModuleValidationTest, CreationSuccess) { |
| const char* shader = R"( |
| OpCapability Shader |
| %1 = OpExtInstImport "GLSL.std.450" |
| OpMemoryModel Logical GLSL450 |
| OpEntryPoint Fragment %main "main" %fragColor |
| OpExecutionMode %main OriginUpperLeft |
| OpSource GLSL 450 |
| OpSourceExtension "GL_GOOGLE_cpp_style_line_directive" |
| OpSourceExtension "GL_GOOGLE_include_directive" |
| OpName %main "main" |
| OpName %fragColor "fragColor" |
| OpDecorate %fragColor Location 0 |
| %void = OpTypeVoid |
| %3 = OpTypeFunction %void |
| %float = OpTypeFloat 32 |
| %v4float = OpTypeVector %float 4 |
| %_ptr_Output_v4float = OpTypePointer Output %v4float |
| %fragColor = OpVariable %_ptr_Output_v4float Output |
| %float_1 = OpConstant %float 1 |
| %float_0 = OpConstant %float 0 |
| %12 = OpConstantComposite %v4float %float_1 %float_0 %float_0 %float_1 |
| %main = OpFunction %void None %3 |
| %5 = OpLabel |
| OpStore %fragColor %12 |
| OpReturn |
| OpFunctionEnd)"; |
| |
| utils::CreateShaderModuleFromASM(device, shader); |
| } |
| |
| // Tests that if the output location exceeds kMaxColorAttachments the fragment shader will fail to |
| // be compiled. |
| TEST_F(ShaderModuleValidationTest, FragmentOutputLocationExceedsMaxColorAttachments) { |
| std::ostringstream stream; |
| stream << "[[stage(fragment)]] fn main() -> [[location(" << kMaxColorAttachments |
| << R"()]] vec4<f32> { |
| return vec4<f32>(0.0, 1.0, 0.0, 1.0); |
| })"; |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, stream.str().c_str())); |
| } |
| |
| // Test that it is invalid to create a shader module with no chained descriptor. (It must be |
| // WGSL or SPIRV, not empty) |
| TEST_F(ShaderModuleValidationTest, NoChainedDescriptor) { |
| wgpu::ShaderModuleDescriptor desc = {}; |
| ASSERT_DEVICE_ERROR(device.CreateShaderModule(&desc)); |
| } |
| |
| // Test that it is not allowed to use combined texture and sampler. |
| TEST_F(ShaderModuleValidationTest, CombinedTextureAndSampler) { |
| // SPIR-V ASM produced by glslang for the following fragment shader: |
| // |
| // #version 450 |
| // layout(set = 0, binding = 0) uniform sampler2D tex; |
| // void main () {} |
| // |
| // Note that the following defines an interface combined texture/sampler which is not allowed |
| // in Dawn / WebGPU. |
| // |
| // %8 = OpTypeSampledImage %7 |
| // %_ptr_UniformConstant_8 = OpTypePointer UniformConstant %8 |
| // %tex = OpVariable %_ptr_UniformConstant_8 UniformConstant |
| const char* shader = R"( |
| OpCapability Shader |
| %1 = OpExtInstImport "GLSL.std.450" |
| OpMemoryModel Logical GLSL450 |
| OpEntryPoint Fragment %main "main" |
| OpExecutionMode %main OriginUpperLeft |
| OpSource GLSL 450 |
| OpName %main "main" |
| OpName %tex "tex" |
| OpDecorate %tex DescriptorSet 0 |
| OpDecorate %tex Binding 0 |
| %void = OpTypeVoid |
| %3 = OpTypeFunction %void |
| %float = OpTypeFloat 32 |
| %7 = OpTypeImage %float 2D 0 0 0 1 Unknown |
| %8 = OpTypeSampledImage %7 |
| %_ptr_UniformConstant_8 = OpTypePointer UniformConstant %8 |
| %tex = OpVariable %_ptr_UniformConstant_8 UniformConstant |
| %main = OpFunction %void None %3 |
| %5 = OpLabel |
| OpReturn |
| OpFunctionEnd |
| )"; |
| |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModuleFromASM(device, shader)); |
| } |
| |
| // Test that it is not allowed to declare a multisampled-array interface texture. |
| // TODO(enga): Also test multisampled cube, cube array, and 3D. These have no GLSL keywords. |
| TEST_F(ShaderModuleValidationTest, MultisampledArrayTexture) { |
| // SPIR-V ASM produced by glslang for the following fragment shader: |
| // |
| // #version 450 |
| // layout(set=0, binding=0) uniform texture2DMSArray tex; |
| // void main () {}} |
| // |
| // Note that the following defines an interface array multisampled texture which is not allowed |
| // in Dawn / WebGPU. |
| // |
| // %7 = OpTypeImage %float 2D 0 1 1 1 Unknown |
| // %_ptr_UniformConstant_7 = OpTypePointer UniformConstant %7 |
| // %tex = OpVariable %_ptr_UniformConstant_7 UniformConstant |
| const char* shader = R"( |
| OpCapability Shader |
| %1 = OpExtInstImport "GLSL.std.450" |
| OpMemoryModel Logical GLSL450 |
| OpEntryPoint Fragment %main "main" |
| OpExecutionMode %main OriginUpperLeft |
| OpSource GLSL 450 |
| OpName %main "main" |
| OpName %tex "tex" |
| OpDecorate %tex DescriptorSet 0 |
| OpDecorate %tex Binding 0 |
| %void = OpTypeVoid |
| %3 = OpTypeFunction %void |
| %float = OpTypeFloat 32 |
| %7 = OpTypeImage %float 2D 0 1 1 1 Unknown |
| %_ptr_UniformConstant_7 = OpTypePointer UniformConstant %7 |
| %tex = OpVariable %_ptr_UniformConstant_7 UniformConstant |
| %main = OpFunction %void None %3 |
| %5 = OpLabel |
| OpReturn |
| OpFunctionEnd |
| )"; |
| |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModuleFromASM(device, shader)); |
| } |
| |
| // Tests that shader module compilation messages can be queried. |
| TEST_F(ShaderModuleValidationTest, GetCompilationMessages) { |
| // This test works assuming ShaderModule is backed by a dawn_native::ShaderModuleBase, which |
| // is not the case on the wire. |
| DAWN_SKIP_TEST_IF(UsesWire()); |
| |
| wgpu::ShaderModule shaderModule = utils::CreateShaderModule(device, R"( |
| [[stage(fragment)]] fn main() -> [[location(0)]] vec4<f32> { |
| return vec4<f32>(0.0, 1.0, 0.0, 1.0); |
| })"); |
| |
| dawn_native::ShaderModuleBase* shaderModuleBase = |
| reinterpret_cast<dawn_native::ShaderModuleBase*>(shaderModule.Get()); |
| dawn_native::OwnedCompilationMessages* messages = shaderModuleBase->GetCompilationMessages(); |
| messages->ClearMessages(); |
| messages->AddMessageForTesting("Info Message"); |
| messages->AddMessageForTesting("Warning Message", wgpu::CompilationMessageType::Warning); |
| messages->AddMessageForTesting("Error Message", wgpu::CompilationMessageType::Error, 3, 4); |
| messages->AddMessageForTesting("Complete Message", wgpu::CompilationMessageType::Info, 3, 4, 5, |
| 6); |
| |
| auto callback = [](WGPUCompilationInfoRequestStatus status, const WGPUCompilationInfo* info, |
| void* userdata) { |
| ASSERT_EQ(WGPUCompilationInfoRequestStatus_Success, status); |
| ASSERT_NE(nullptr, info); |
| ASSERT_EQ(4u, info->messageCount); |
| |
| const WGPUCompilationMessage* message = &info->messages[0]; |
| ASSERT_STREQ("Info Message", message->message); |
| ASSERT_EQ(WGPUCompilationMessageType_Info, message->type); |
| ASSERT_EQ(0u, message->lineNum); |
| ASSERT_EQ(0u, message->linePos); |
| |
| message = &info->messages[1]; |
| ASSERT_STREQ("Warning Message", message->message); |
| ASSERT_EQ(WGPUCompilationMessageType_Warning, message->type); |
| ASSERT_EQ(0u, message->lineNum); |
| ASSERT_EQ(0u, message->linePos); |
| |
| message = &info->messages[2]; |
| ASSERT_STREQ("Error Message", message->message); |
| ASSERT_EQ(WGPUCompilationMessageType_Error, message->type); |
| ASSERT_EQ(3u, message->lineNum); |
| ASSERT_EQ(4u, message->linePos); |
| |
| message = &info->messages[3]; |
| ASSERT_STREQ("Complete Message", message->message); |
| ASSERT_EQ(WGPUCompilationMessageType_Info, message->type); |
| ASSERT_EQ(3u, message->lineNum); |
| ASSERT_EQ(4u, message->linePos); |
| ASSERT_EQ(5u, message->offset); |
| ASSERT_EQ(6u, message->length); |
| }; |
| |
| shaderModule.GetCompilationInfo(callback, nullptr); |
| } |
| |
| // Validate the maximum location of effective inter-stage variables cannot be greater than 14 |
| // (kMaxInterStageShaderComponents / 4 - 1). |
| TEST_F(ShaderModuleValidationTest, MaximumShaderIOLocations) { |
| auto generateShaderForTest = [](uint32_t maximumOutputLocation, wgpu::ShaderStage shaderStage) { |
| std::ostringstream stream; |
| stream << "struct ShaderIO {" << std::endl; |
| for (uint32_t location = 1; location <= maximumOutputLocation; ++location) { |
| stream << "[[location(" << location << ")]] var" << location << ": f32;" << std::endl; |
| } |
| switch (shaderStage) { |
| case wgpu::ShaderStage::Vertex: { |
| stream << R"( |
| [[builtin(position)]] pos: vec4<f32>; |
| }; |
| [[stage(vertex)]] fn main() -> ShaderIO { |
| var shaderIO : ShaderIO; |
| shaderIO.pos = vec4<f32>(0.0, 0.0, 0.0, 1.0); |
| return shaderIO; |
| })"; |
| } break; |
| |
| case wgpu::ShaderStage::Fragment: { |
| stream << R"( |
| }; |
| [[stage(fragment)]] fn main(shaderIO: ShaderIO) -> [[location(0)]] vec4<f32> { |
| return vec4<f32>(0.0, 0.0, 0.0, 1.0); |
| })"; |
| } break; |
| |
| case wgpu::ShaderStage::Compute: |
| default: |
| UNREACHABLE(); |
| } |
| |
| return stream.str(); |
| }; |
| |
| constexpr uint32_t kMaxInterShaderIOLocation = kMaxInterStageShaderComponents / 4 - 1; |
| |
| // It is allowed to create a shader module with the maximum active vertex output location == 14; |
| { |
| std::string vertexShader = |
| generateShaderForTest(kMaxInterShaderIOLocation, wgpu::ShaderStage::Vertex); |
| utils::CreateShaderModule(device, vertexShader.c_str()); |
| } |
| |
| // It isn't allowed to create a shader module with the maximum active vertex output location > |
| // 14; |
| { |
| std::string vertexShader = |
| generateShaderForTest(kMaxInterShaderIOLocation + 1, wgpu::ShaderStage::Vertex); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, vertexShader.c_str())); |
| } |
| |
| // It is allowed to create a shader module with the maximum active fragment input location == |
| // 14; |
| { |
| std::string fragmentShader = |
| generateShaderForTest(kMaxInterShaderIOLocation, wgpu::ShaderStage::Fragment); |
| utils::CreateShaderModule(device, fragmentShader.c_str()); |
| } |
| |
| // It is allowed to create a shader module with the maximum active vertex output location > 14; |
| { |
| std::string fragmentShader = |
| generateShaderForTest(kMaxInterShaderIOLocation + 1, wgpu::ShaderStage::Fragment); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, fragmentShader.c_str())); |
| } |
| } |
| |
| // Validate the maximum number of total inter-stage user-defined variable component count and |
| // built-in variables cannot exceed kMaxInterStageShaderComponents. |
| TEST_F(ShaderModuleValidationTest, MaximumInterStageShaderComponents) { |
| auto generateShaderForTest = [](uint32_t totalUserDefinedInterStageShaderComponentCount, |
| wgpu::ShaderStage shaderStage, |
| const char* builtInDeclarations) { |
| std::ostringstream stream; |
| stream << "struct ShaderIO {" << std::endl << builtInDeclarations << std::endl; |
| uint32_t vec4InputLocations = totalUserDefinedInterStageShaderComponentCount / 4; |
| |
| for (uint32_t location = 0; location < vec4InputLocations; ++location) { |
| stream << "[[location(" << location << ")]] var" << location << ": vec4<f32>;" |
| << std::endl; |
| } |
| |
| uint32_t lastComponentCount = totalUserDefinedInterStageShaderComponentCount % 4; |
| if (lastComponentCount > 0) { |
| stream << "[[location(" << vec4InputLocations << ")]] var" << vec4InputLocations |
| << ": "; |
| if (lastComponentCount == 1) { |
| stream << "f32;"; |
| } else { |
| stream << " vec" << lastComponentCount << "<f32>;"; |
| } |
| stream << std::endl; |
| } |
| |
| switch (shaderStage) { |
| case wgpu::ShaderStage::Vertex: { |
| stream << R"( |
| [[builtin(position)]] pos: vec4<f32>; |
| }; |
| [[stage(vertex)]] fn main() -> ShaderIO { |
| var shaderIO : ShaderIO; |
| shaderIO.pos = vec4<f32>(0.0, 0.0, 0.0, 1.0); |
| return shaderIO; |
| })"; |
| } break; |
| |
| case wgpu::ShaderStage::Fragment: { |
| stream << R"( |
| }; |
| [[stage(fragment)]] fn main(shaderIO: ShaderIO) -> [[location(0)]] vec4<f32> { |
| return vec4<f32>(0.0, 0.0, 0.0, 1.0); |
| })"; |
| } break; |
| |
| case wgpu::ShaderStage::Compute: |
| default: |
| UNREACHABLE(); |
| } |
| |
| return stream.str(); |
| }; |
| |
| // Verify when there is no input builtin variable in a fragment shader, the total user-defined |
| // input component count must be less than kMaxInterStageShaderComponents. |
| { |
| constexpr uint32_t kInterStageShaderComponentCount = kMaxInterStageShaderComponents; |
| std::string correctFragmentShader = |
| generateShaderForTest(kInterStageShaderComponentCount, wgpu::ShaderStage::Fragment, ""); |
| utils::CreateShaderModule(device, correctFragmentShader.c_str()); |
| |
| std::string errorFragmentShader = generateShaderForTest(kInterStageShaderComponentCount + 1, |
| wgpu::ShaderStage::Fragment, ""); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, errorFragmentShader.c_str())); |
| } |
| |
| // [[position]] should be counted into the maximum inter-stage component count. |
| // Note that in vertex shader we always have [[position]] so we don't need to specify it |
| // again in the parameter "builtInDeclarations" of generateShaderForTest(). |
| { |
| constexpr uint32_t kInterStageShaderComponentCount = kMaxInterStageShaderComponents - 4; |
| std::string vertexShader = |
| generateShaderForTest(kInterStageShaderComponentCount, wgpu::ShaderStage::Vertex, ""); |
| utils::CreateShaderModule(device, vertexShader.c_str()); |
| |
| std::string fragmentShader = |
| generateShaderForTest(kInterStageShaderComponentCount, wgpu::ShaderStage::Fragment, |
| "[[builtin(position)]] fragCoord: vec4<f32>;"); |
| utils::CreateShaderModule(device, fragmentShader.c_str()); |
| } |
| |
| { |
| constexpr uint32_t kInterStageShaderComponentCount = kMaxInterStageShaderComponents - 3; |
| std::string vertexShader = |
| generateShaderForTest(kInterStageShaderComponentCount, wgpu::ShaderStage::Vertex, ""); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, vertexShader.c_str())); |
| |
| std::string fragmentShader = |
| generateShaderForTest(kInterStageShaderComponentCount, wgpu::ShaderStage::Fragment, |
| "[[builtin(position)]] fragCoord: vec4<f32>;"); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, fragmentShader.c_str())); |
| } |
| |
| // [[front_facing]] should be counted into the maximum inter-stage component count. |
| { |
| const char* builtinDeclaration = "[[builtin(front_facing)]] frontFacing : bool;"; |
| |
| { |
| std::string fragmentShader = |
| generateShaderForTest(kMaxInterStageShaderComponents - 1, |
| wgpu::ShaderStage::Fragment, builtinDeclaration); |
| utils::CreateShaderModule(device, fragmentShader.c_str()); |
| } |
| |
| { |
| std::string fragmentShader = generateShaderForTest( |
| kMaxInterStageShaderComponents, wgpu::ShaderStage::Fragment, builtinDeclaration); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, fragmentShader.c_str())); |
| } |
| } |
| |
| // [[sample_index]] should be counted into the maximum inter-stage component count. |
| { |
| const char* builtinDeclaration = "[[builtin(sample_index)]] sampleIndex: u32;"; |
| |
| { |
| std::string fragmentShader = |
| generateShaderForTest(kMaxInterStageShaderComponents - 1, |
| wgpu::ShaderStage::Fragment, builtinDeclaration); |
| utils::CreateShaderModule(device, fragmentShader.c_str()); |
| } |
| |
| { |
| std::string fragmentShader = generateShaderForTest( |
| kMaxInterStageShaderComponents, wgpu::ShaderStage::Fragment, builtinDeclaration); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, fragmentShader.c_str())); |
| } |
| } |
| |
| // [[sample_mask]] should be counted into the maximum inter-stage component count. |
| { |
| const char* builtinDeclaration = "[[builtin(front_facing)]] frontFacing : bool;"; |
| |
| { |
| std::string fragmentShader = |
| generateShaderForTest(kMaxInterStageShaderComponents - 1, |
| wgpu::ShaderStage::Fragment, builtinDeclaration); |
| utils::CreateShaderModule(device, fragmentShader.c_str()); |
| } |
| |
| { |
| std::string fragmentShader = generateShaderForTest( |
| kMaxInterStageShaderComponents, wgpu::ShaderStage::Fragment, builtinDeclaration); |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, fragmentShader.c_str())); |
| } |
| } |
| } |
| |
| // Tests that we validate workgroup size limits. |
| TEST_F(ShaderModuleValidationTest, ComputeWorkgroupSizeLimits) { |
| DAWN_SKIP_TEST_IF(!HasToggleEnabled("use_tint_generator")); |
| |
| auto MakeShaderWithWorkgroupSize = [this](uint32_t x, uint32_t y, uint32_t z) { |
| std::ostringstream ss; |
| ss << "[[stage(compute), workgroup_size(" << x << "," << y << "," << z |
| << ")]] fn main() {}"; |
| utils::CreateShaderModule(device, ss.str().c_str()); |
| }; |
| |
| wgpu::Limits supportedLimits = GetSupportedLimits().limits; |
| |
| MakeShaderWithWorkgroupSize(1, 1, 1); |
| MakeShaderWithWorkgroupSize(supportedLimits.maxComputeWorkgroupSizeX, 1, 1); |
| MakeShaderWithWorkgroupSize(1, supportedLimits.maxComputeWorkgroupSizeY, 1); |
| MakeShaderWithWorkgroupSize(1, 1, supportedLimits.maxComputeWorkgroupSizeZ); |
| |
| ASSERT_DEVICE_ERROR( |
| MakeShaderWithWorkgroupSize(supportedLimits.maxComputeWorkgroupSizeX + 1, 1, 1)); |
| ASSERT_DEVICE_ERROR( |
| MakeShaderWithWorkgroupSize(1, supportedLimits.maxComputeWorkgroupSizeY + 1, 1)); |
| ASSERT_DEVICE_ERROR( |
| MakeShaderWithWorkgroupSize(1, 1, supportedLimits.maxComputeWorkgroupSizeZ + 1)); |
| |
| // No individual dimension exceeds its limit, but the combined size should definitely exceed the |
| // total invocation limit. |
| ASSERT_DEVICE_ERROR(MakeShaderWithWorkgroupSize(supportedLimits.maxComputeWorkgroupSizeX, |
| supportedLimits.maxComputeWorkgroupSizeY, |
| supportedLimits.maxComputeWorkgroupSizeZ)); |
| } |
| |
| // Tests that we validate workgroup storage size limits. |
| TEST_F(ShaderModuleValidationTest, ComputeWorkgroupStorageSizeLimits) { |
| DAWN_SKIP_TEST_IF(!HasToggleEnabled("use_tint_generator")); |
| |
| wgpu::Limits supportedLimits = GetSupportedLimits().limits; |
| |
| constexpr uint32_t kVec4Size = 16; |
| const uint32_t maxVec4Count = supportedLimits.maxComputeWorkgroupStorageSize / kVec4Size; |
| constexpr uint32_t kMat4Size = 64; |
| const uint32_t maxMat4Count = supportedLimits.maxComputeWorkgroupStorageSize / kMat4Size; |
| |
| auto MakeShaderWithWorkgroupStorage = [this](uint32_t vec4_count, uint32_t mat4_count) { |
| std::ostringstream ss; |
| std::ostringstream body; |
| if (vec4_count > 0) { |
| ss << "var<workgroup> vec4_data: array<vec4<f32>, " << vec4_count << ">;"; |
| body << "ignore(vec4_data);"; |
| } |
| if (mat4_count > 0) { |
| ss << "var<workgroup> mat4_data: array<mat4x4<f32>, " << mat4_count << ">;"; |
| body << "ignore(mat4_data);"; |
| } |
| ss << "[[stage(compute), workgroup_size(1)]] fn main() { " << body.str() << " }"; |
| utils::CreateShaderModule(device, ss.str().c_str()); |
| }; |
| |
| MakeShaderWithWorkgroupStorage(1, 1); |
| MakeShaderWithWorkgroupStorage(maxVec4Count, 0); |
| MakeShaderWithWorkgroupStorage(0, maxMat4Count); |
| MakeShaderWithWorkgroupStorage(maxVec4Count - 4, 1); |
| MakeShaderWithWorkgroupStorage(4, maxMat4Count - 1); |
| ASSERT_DEVICE_ERROR(MakeShaderWithWorkgroupStorage(maxVec4Count + 1, 0)); |
| ASSERT_DEVICE_ERROR(MakeShaderWithWorkgroupStorage(maxVec4Count - 3, 1)); |
| ASSERT_DEVICE_ERROR(MakeShaderWithWorkgroupStorage(0, maxMat4Count + 1)); |
| ASSERT_DEVICE_ERROR(MakeShaderWithWorkgroupStorage(4, maxMat4Count)); |
| } |
| |
| // Test that numeric ID must be unique |
| TEST_F(ShaderModuleValidationTest, OverridableConstantsNumericIDConflicts) { |
| ASSERT_DEVICE_ERROR(utils::CreateShaderModule(device, R"( |
| [[override(1234)]] let c0: u32; |
| [[override(1234)]] let c1: u32; |
| |
| [[block]] struct Buf { |
| data : array<u32, 2>; |
| }; |
| |
| [[group(0), binding(0)]] var<storage, read_write> buf : Buf; |
| |
| [[stage(compute), workgroup_size(1)]] fn main() { |
| // make sure the overridable constants are not optimized out |
| buf.data[0] = c0; |
| buf.data[1] = c1; |
| })")); |
| } |