Add kernel and kernel writer skeletons

* Add the skeleton for kernel, kernel writer and their respective
  OpenCL implementation.
* Add method to write code comment and its test.

Resolves: COMPMID-6343
Signed-off-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Change-Id: Ib986228154f7a00da7a5fd3b7105941325fe13b1
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/9889
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>

13 files changed, 712 insertions, 6 deletions

diff --git a/compute_kernel_writer/CMakeLists.txt b/compute_kernel_writer/CMakeLists.txt
index 3bc2aeda63..d763bc6de5 100644
--- a/compute_kernel_writer/CMakeLists.txt
+++ b/compute_kernel_writer/CMakeLists.txt
@@ -124,6 +124,8 @@ target_sources(ckw PRIVATE
     src/TensorUtils.cpp
     src/TileInfo.cpp
     src/ITileOperand.cpp
+    src/Kernel.cpp
+    src/KernelWriter.cpp
 )
 
 if(CKW_ENABLE_OPENCL)
@@ -132,6 +134,7 @@ if(CKW_ENABLE_OPENCL)
         src/cl/CLHelpers.cpp
         src/cl/CLTile.cpp
         src/cl/ICLTile.cpp
+        src/cl/CLKernelWriter.cpp
     )
 endif()
 
@@ -145,9 +148,6 @@ target_include_directories(ckw
 
 if(CKW_BUILD_TESTING)
     add_executable(ckw_validation
-        validation/tests/common/Common.h
-        validation/tests/TensorBitMaskTest.hpp
-        validation/tests/UtilsTest.hpp
         validation/Validation.cpp
     )
     if(CKW_ENABLE_OPENCL)
diff --git a/compute_kernel_writer/include/ckw/Error.h b/compute_kernel_writer/include/ckw/Error.h
index 2793791802..100bdc48fe 100644
--- a/compute_kernel_writer/include/ckw/Error.h
+++ b/compute_kernel_writer/include/ckw/Error.h
@@ -21,8 +21,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-#ifndef COMPUTE_KERNEL_WRITER_INCLUDE_CKW_ERROR_H
-#define COMPUTE_KERNEL_WRITER_INCLUDE_CKW_ERROR_H
+#ifndef CKW_INCLUDE_CKW_ERROR_H
+#define CKW_INCLUDE_CKW_ERROR_H
 
 #include <stdexcept>
 #include <string>
@@ -55,6 +55,65 @@ create_error_msg(const std::string &file, const std::string &func, const std::st
         std::runtime_error(create_error_msg(arg0, arg1, arg2, arg3)); \
     } while(false)
 
+/** Mark the variables as unused.
+ *
+ * @param[in] ... Variables which are unused.
+ */
+#define CKW_UNUSED(...) ckw::ignore_unused(__VA_ARGS__) // NOLINT
+
+/** Mark the variables as unused.
+ *
+ * @param[in] ... Variables which are unused.
+ */
+template <typename... T>
+inline void ignore_unused(T &&...)
+{
+}
+
+/** Throw an std::runtime_error with the specified message.
+ *
+ * @param[in] msg The error message.
+ */
+#define CKW_THROW_MSG(msg)                                                              \
+    do                                                                                  \
+    {                                                                                   \
+        const std::string file(__FILE__);                                               \
+        const std::string func(__func__);                                               \
+        const std::string line(std::to_string(__LINE__));                               \
+        const std::string message(msg);                                                 \
+                                                                                        \
+        throw std::runtime_error(ckw::create_error_msg(file, func, line, message)); \
+    } while(false)
+
+#ifdef COMPUTE_KERNEL_WRITER_ASSERTS_ENABLED
+
+/** If the condition is not met, throw an std::runtime_error with the specified message.
+ *
+ * @param[in] cond The condition that is expected to be true.
+ * @param[in] msg  The error message when the condition is not met.
+ */
+#define CKW_ASSERT_MSG(cond, msg) \
+    do                            \
+    {                             \
+        if(!(cond))               \
+        {                         \
+            CKW_THROW_MSG(msg);   \
+        }                         \
+    } while(false)
+
+/** If the condition is not met, throw an std::runtime_error.
+ *
+ * @param[in] cond The condition that is expected to be true.
+ */
+#define CKW_ASSERT(cond) CKW_ASSERT_MSG(cond, #cond)
+
+#else // COMPUTE_KERNEL_WRITER_ASSERTS_ENABLED
+
+#define CKW_ASSERT_MSG(cond, msg)
+#define CKW_ASSERT(cond)
+
+#endif // COMPUTE_KERNEL_WRITER_ASSERTS_ENABLED
+
 } // namespace ckw
 
-#endif /* COMPUTE_KERNEL_WRITER_INCLUDE_CKW_ERROR_H */
+#endif // CKW_INCLUDE_CKW_ERROR_H
diff --git a/compute_kernel_writer/include/ckw/Kernel.h b/compute_kernel_writer/include/ckw/Kernel.h
new file mode 100644
index 0000000000..0cab713c48
--- /dev/null
+++ b/compute_kernel_writer/include/ckw/Kernel.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CKW_INCLUDE_CKW_KERNEL_H
+#define CKW_INCLUDE_CKW_KERNEL_H
+
+#include "ckw/types/TargetLanguage.h"
+#include <string>
+
+namespace ckw
+{
+
+/** The kernel that has been emitted by the kernel writer.
+ *
+ * It contains all the necessary information to compile and execute the kernel.
+ */
+class Kernel
+{
+public:
+    /** Initialize a new instance of @ref Kernel class with all emitted kernel information.
+     *
+     * @param[in] language    The target language of the kernel.
+     * @param[in] source_code The source code of the kernel.
+     */
+    Kernel(TargetLanguage language, const std::string &source_code);
+
+    /** Get the target language. */
+    TargetLanguage target_language() const;
+
+    /** Get the source code. */
+    const std::string &source_code() const;
+
+private:
+    TargetLanguage _language;
+    std::string    _source_code;
+};
+
+} // namespace ckw
+
+#endif // CKW_INCLUDE_CKW_KERNEL_H
diff --git a/compute_kernel_writer/include/ckw/KernelWriter.h b/compute_kernel_writer/include/ckw/KernelWriter.h
new file mode 100644
index 0000000000..ba8a6015e6
--- /dev/null
+++ b/compute_kernel_writer/include/ckw/KernelWriter.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CKW_INCLUDE_CKW_KERNELWRITER_H
+#define CKW_INCLUDE_CKW_KERNELWRITER_H
+
+#include "ckw/types/TargetArchitecture.h"
+#include "ckw/types/TargetLanguage.h"
+#include <memory>
+#include <string>
+
+namespace ckw
+{
+
+class Kernel;
+
+/** A kernel writer.
+ *
+ * This class is used to construct a new kernel by defining arguments, declaring variable and writing code.
+ *
+ * Use @ref KernelWriter::create_instance method to create the kernel writer for the specific target architecture and language.
+ *
+ * After having finished constructing the kernel, call @ref KernelWriter::emit_kernel to get the kernel object.
+ */
+class KernelWriter
+{
+public:
+    // =============================================================================================
+    // Construtors and destructor
+    // =============================================================================================
+
+    /** Initialize a new instance of @ref KernelWriter class for the specific architecture and language.
+     *
+     * Supported target architectures and languages:
+     *
+     * Architecture                  | Languages                    |
+     * ------------------------------|------------------------------|
+     * GpuArmMaliValhall             | OpenCL                       |
+     *
+     * @param[in] architecture The architecture on which the kernel is executed.
+     * @param[in] language     The language to write the kernel.
+     */
+    static std::unique_ptr<KernelWriter> create_instance(TargetArchitecture architecture, TargetLanguage language);
+
+    /** Destructor */
+    virtual ~KernelWriter();
+
+    // =============================================================================================
+    // Misc
+    // =============================================================================================
+
+    /** Write the line comment in debug build.
+     * This function does not take effect on release build.
+     *
+     * The comment must only contain one line (i.e. no newline character is allowed).
+     *
+     * @param[in] text The comment to be written.
+     */
+    virtual void comment(const std::string &text) = 0;
+
+    // =============================================================================================
+    // Code generation
+    // =============================================================================================
+
+    /** Emit the kernel object.
+     *
+     * @param[in] name The name of the kernel object to be generated.
+     */
+    virtual std::unique_ptr<Kernel> emit_kernel(const std::string &name) = 0;
+};
+
+} // namespace ckw
+
+#endif // CKW_INCLUDE_CKW_KERNELWRITER_H
diff --git a/compute_kernel_writer/include/ckw/types/TargetArchitecture.h b/compute_kernel_writer/include/ckw/types/TargetArchitecture.h
new file mode 100644
index 0000000000..25662a01f0
--- /dev/null
+++ b/compute_kernel_writer/include/ckw/types/TargetArchitecture.h
@@ -0,0 +1,40 @@
+/*
+* Copyright (c) 2023 Arm Limited.
+*
+* SPDX-License-Identifier: MIT
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to
+* deal in the Software without restriction, including without limitation the
+* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+* sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all
+* copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+* SOFTWARE.
+*/
+
+#ifndef CKW_INCLUDE_CKW_TYPES_TARGETARCHITECTURE_H
+#define CKW_INCLUDE_CKW_TYPES_TARGETARCHITECTURE_H
+
+namespace ckw
+{
+
+/** Target platform architecture. */
+enum class TargetArchitecture
+{
+    Unknown,
+    GpuArmMaliValhall,
+};
+
+} // namespace ckw
+
+#endif // CKW_INCLUDE_CKW_TYPES_TARGETARCHITECTURE_H
diff --git a/compute_kernel_writer/include/ckw/types/TargetLanguage.h b/compute_kernel_writer/include/ckw/types/TargetLanguage.h
new file mode 100644
index 0000000000..1f507573dd
--- /dev/null
+++ b/compute_kernel_writer/include/ckw/types/TargetLanguage.h
@@ -0,0 +1,40 @@
+/*
+* Copyright (c) 2023 Arm Limited.
+*
+* SPDX-License-Identifier: MIT
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to
+* deal in the Software without restriction, including without limitation the
+* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+* sell copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in all
+* copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+* SOFTWARE.
+*/
+
+#ifndef CKW_INCLUDE_CKW_TYPES_TARGETLANGUAGE_H
+#define CKW_INCLUDE_CKW_TYPES_TARGETLANGUAGE_H
+
+namespace ckw
+{
+
+/** Target language. */
+enum class TargetLanguage
+{
+    Unknown,
+    OpenCL
+};
+
+} // namespace ckw
+
+#endif // CKW_INCLUDE_CKW_TYPES_TARGETLANGUAGE_H
diff --git a/compute_kernel_writer/src/Kernel.cpp b/compute_kernel_writer/src/Kernel.cpp
new file mode 100644
index 0000000000..ccc68ecefb
--- /dev/null
+++ b/compute_kernel_writer/src/Kernel.cpp
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "ckw/Kernel.h"
+
+namespace ckw
+{
+
+Kernel::Kernel(TargetLanguage language, const std::string &source_code)
+    : _language(language), _source_code(source_code)
+{
+}
+
+TargetLanguage Kernel::target_language() const
+{
+    return _language;
+}
+
+const std::string &Kernel::source_code() const
+{
+    return _source_code;
+}
+
+} // namespace ckw
diff --git a/compute_kernel_writer/src/KernelWriter.cpp b/compute_kernel_writer/src/KernelWriter.cpp
new file mode 100644
index 0000000000..eb8399a7ef
--- /dev/null
+++ b/compute_kernel_writer/src/KernelWriter.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "ckw/KernelWriter.h"
+#include "ckw/Error.h"
+#include "src/cl/CLKernelWriter.h"
+
+namespace ckw
+{
+
+std::unique_ptr<KernelWriter> KernelWriter::create_instance(TargetArchitecture architecture, TargetLanguage language)
+{
+    switch(language)
+    {
+        case TargetLanguage::OpenCL:
+            // Currently this is the oldest and the only supported GPU architecture.
+            CKW_ASSERT(architecture == TargetArchitecture::GpuArmMaliValhall);
+            return std::make_unique<CLKernelWriter>();
+
+        default:
+            CKW_THROW_MSG("Language not supported!");
+    }
+}
+
+KernelWriter::~KernelWriter() = default;
+
+} // namespace ckw
diff --git a/compute_kernel_writer/src/cl/CLKernelWriter.cpp b/compute_kernel_writer/src/cl/CLKernelWriter.cpp
new file mode 100644
index 0000000000..231d321c22
--- /dev/null
+++ b/compute_kernel_writer/src/cl/CLKernelWriter.cpp
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "src/cl/CLKernelWriter.h"
+#include "ckw/Error.h"
+
+namespace ckw
+{
+
+CLKernelWriter::CLKernelWriter()
+{
+}
+
+CLKernelWriter::~CLKernelWriter() = default;
+
+std::unique_ptr<Kernel> CLKernelWriter::emit_kernel(const std::string &name)
+{
+    CKW_UNUSED(name);
+    CKW_THROW_MSG("Not implemented!");
+}
+
+void CLKernelWriter::comment(const std::string &text)
+{
+#ifdef COMPUTE_KERNEL_WRITER_DEBUG_ENABLED
+
+    CKW_ASSERT(text.find("\n") == text.npos);
+    CKW_ASSERT(text.find("\r") == text.npos);
+
+    append_code("// ", text, "\n");
+
+#else // COMPUTE_KERNEL_WRITER_DEBUG_ENABLED
+
+    CKW_UNUSED(text);
+
+#endif // COMPUTE_KERNEL_WRITER_DEBUG_ENABLED
+}
+
+const std::string &CLKernelWriter::body_source_code() const
+{
+    return _body_source_code;
+}
+
+} // namespace ckw
diff --git a/compute_kernel_writer/src/cl/CLKernelWriter.h b/compute_kernel_writer/src/cl/CLKernelWriter.h
new file mode 100644
index 0000000000..e6f0641538
--- /dev/null
+++ b/compute_kernel_writer/src/cl/CLKernelWriter.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CKW_SRC_CL_CLKERNELWRITER_H
+#define CKW_SRC_CL_CLKERNELWRITER_H
+
+#include "ckw/KernelWriter.h"
+#include <utility>
+
+namespace ckw
+{
+
+/** OpenCL kernel writer. */
+class CLKernelWriter : public KernelWriter
+{
+public:
+    // =============================================================================================
+    // Construtors and destructor
+    // =============================================================================================
+
+    /** Initialize a new instance of @ref CLKernelWriter class. */
+    CLKernelWriter();
+
+    /** Destructor */
+    ~CLKernelWriter();
+
+    // =============================================================================================
+    // Misc
+    // =============================================================================================
+
+    void comment(const std::string &text) override;
+
+    // =============================================================================================
+    // Code generation
+    // =============================================================================================
+
+    std::unique_ptr<Kernel> emit_kernel(const std::string &name) override;
+
+protected:
+    /** Append the specified code to the kernel body source code. */
+    template <typename T, typename... TArgs>
+    void append_code(T &&code, TArgs &&...args)
+    {
+        append_code(std::forward<T>(code));
+        append_code(std::forward<TArgs>(args)...);
+    }
+
+    /** Append the specified code to the kernel body source code. */
+    template <typename T>
+    void append_code(T &&code)
+    {
+        _body_source_code += std::forward<T>(code);
+    }
+
+    /** Get the current kernel body source code. */
+    const std::string &body_source_code() const;
+
+private:
+    /** This string contains the kernel body source code, not the full CL source code.
+     * The full source code will only be generated when the user calls @ref KernelWriter::emit_kernel.
+     *
+     * In order to add code to this, use @ref CLKernelWriter::append_code.
+     * Do not attempt to concatenate and alter this string directly.
+     */
+    std::string _body_source_code{};
+};
+
+} // namespace ckw
+
+#endif // CKW_SRC_CL_CLKERNELWRITER_H
diff --git a/compute_kernel_writer/validation/Validation.cpp b/compute_kernel_writer/validation/Validation.cpp
index 16c0d7696d..c0bdaaa0dc 100644
--- a/compute_kernel_writer/validation/Validation.cpp
+++ b/compute_kernel_writer/validation/Validation.cpp
@@ -26,6 +26,7 @@
 #include "tests/CLTileTest.hpp"
 #include "tests/TensorBitMaskTest.hpp"
 #include "tests/UtilsTest.hpp"
+#include "tests/CLKernelWriterTest.h"
 
 #include <memory>
 #include <vector>
@@ -59,6 +60,7 @@ int32_t main()
     const auto test12 = std::make_unique<CLConstantTileAccessScalarVariableBroadcastYTest>();
     const auto test13 = std::make_unique<CLConstantTileAccessVectorVariablesTest>();
     const auto test14 = std::make_unique<CLConstantTileAccessSubVectorVariablesTest>();
+    const auto test15 = std::make_unique<CLKernelWriterCommentTest>();
 
     tests.push_back(test3.get());
     tests.push_back(test4.get());
@@ -72,6 +74,7 @@ int32_t main()
     tests.push_back(test12.get());
     tests.push_back(test13.get());
     tests.push_back(test14.get());
+    tests.push_back(test15.get());
 #endif /* COMPUTE_KERNEL_WRITER_OPENCL_ENABLED */
 
     bool all_test_passed = true;
diff --git a/compute_kernel_writer/validation/tests/CLKernelWriterTest.h b/compute_kernel_writer/validation/tests/CLKernelWriterTest.h
new file mode 100644
index 0000000000..ff09ea8073
--- /dev/null
+++ b/compute_kernel_writer/validation/tests/CLKernelWriterTest.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CKW_VALIDATION_TESTS_CLKERNELTEST_H
+#define CKW_VALIDATION_TESTS_CLKERNELTEST_H
+
+#include "src/cl/CLKernelWriter.h"
+#include "validation/tests/common/Common.h"
+#include "validation/tests/common/KernelWriterInterceptor.h"
+
+namespace ckw
+{
+
+class CLKernelWriterCommentTest : public ITest
+{
+public:
+    CLKernelWriterCommentTest()
+    {
+    }
+
+    bool run() override
+    {
+        bool all_tests_passed = true;
+
+        KernelWriterInterceptor<CLKernelWriter> writer;
+
+        writer.comment("previous code");
+
+        writer.start_capture_code();
+
+        writer.comment("code under test 0");
+        writer.comment("code under test 1");
+
+        constexpr auto expected_code = "// code under test 0\n// code under test 1\n";
+
+        VALIDATE_TEST(writer.check_added_code(expected_code), all_tests_passed, 0);
+
+        return all_tests_passed;
+    }
+
+    std::string name() override
+    {
+        return "CLKernelWriterCommentTest";
+    }
+};
+
+} // namespace ckw
+
+#endif // CKW_VALIDATION_TESTS_CLKERNELTEST_H
diff --git a/compute_kernel_writer/validation/tests/common/KernelWriterInterceptor.h b/compute_kernel_writer/validation/tests/common/KernelWriterInterceptor.h
new file mode 100644
index 0000000000..89bb76e37f
--- /dev/null
+++ b/compute_kernel_writer/validation/tests/common/KernelWriterInterceptor.h
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2023 Arm Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CKW_VALIDATION_TESTS_COMMON_KERNELWRITERINTERCEPTOR_H
+#define CKW_VALIDATION_TESTS_COMMON_KERNELWRITERINTERCEPTOR_H
+
+#include <string>
+#include <utility>
+
+namespace ckw
+{
+
+/** This class provides the ability to capture only the code changed after a point
+ * and compares that part of code with the expected value.
+ *
+ * It is useful for testing purpose when a particular sequence of instructions is interested
+ * while the rest of the initialization code is out of scope.
+ */
+template <typename T>
+class KernelWriterInterceptor : public T
+{
+public:
+    template <typename... TArgs>
+    KernelWriterInterceptor(const TArgs &&...args)
+        : T(std::forward<TArgs>(args)...)
+    {
+    }
+
+    /** Mark this point in the source code as the start position to capture.
+     * Only source code added after this function is considered when check_add_code is called.
+     */
+    void start_capture_code()
+    {
+        _start_code = this->body_source_code();
+    }
+
+    /** Compare the source code added after start_capture_code is called the the specified expected code. */
+    bool check_added_code(const std::string &expected_added_code)
+    {
+        const auto &end_code = this->body_source_code();
+
+        // Code can only grow over time.
+        if(end_code.length() < _start_code.length())
+        {
+            return false;
+        }
+
+        // New code must be added to the source code without changing the already existed code.
+        if(end_code.substr(0, _start_code.length()) != _start_code)
+        {
+            return false;
+        }
+
+        // The newly added code must match the expected value.
+        if(end_code.substr(_start_code.length(), end_code.length() - _start_code.length()) != expected_added_code)
+        {
+            return false;
+        }
+
+        return true;
+    }
+
+private:
+    std::string _start_code{};
+};
+
+} // namespace ckw
+
+#endif // CKW_VALIDATION_TESTS_COMMON_KERNELWRITERINTERCEPTOR_H