OpenCL rules for Bazel

Bazel rules for compiling OpenCL source files (.cl) to C++ header files (.cl.h).

Overview

rules_opencl provides Bazel rules for compiling OpenCL source files into C++ header files. The generated header files include:

• OpenCL source code as C++ string constants
• Automatically extracted kernel name arrays
• Preserved original comments (optional)

Installation

Using Bazel MODULE.bazel (Recommended)

Add the following to your MODULE.bazel file:

bazel_dep(name = "rules_opencl", version = "1.0.0")

# Use git_override to point to GitHub repository
git_override(
    module_name = "rules_opencl",
    remote = "https://github.com/SilvesterHsu/rules_opencl.git",
    commit = "your-commit-hash",  # Replace with actual commit hash
)

# Or use archive_override (recommended for releases)
# archive_override(
#     module_name = "rules_opencl",
#     urls = ["https://github.com/SilvesterHsu/rules_opencl/archive/v1.0.0.tar.gz"],
#     strip_prefix = "rules_opencl-1.0.0",
#     integrity = "sha256-...",  # Calculate actual sha256
# )

Usage

Basic Usage

In your BUILD.bazel file:

load("@rules_opencl//:opencl.bzl", "opencl_library")

opencl_library(
    name = "my_kernel_cl",
    srcs = ["my_kernel.cl"],
)

cc_library(
    name = "my_kernel_cl_hdr",
    hdrs = [":my_kernel_cl"],
)

cc_binary(
    name = "my_program",
    srcs = ["my_program.cc"],
    deps = [":my_kernel_cl_hdr"],
)

Advanced Usage

Using Include Directories

opencl_library(
    name = "my_kernel_cl",
    srcs = ["my_kernel.cl"],
    include_dirs = ["kernels/common", "kernels/utils"],
    hdrs = ["kernels/common/definitions.cl"],
)

Specifying Variable Name

opencl_library(
    name = "my_kernel_cl",
    srcs = ["my_kernel.cl"],
    var = "my_custom_kernel_source",
)

Using in C++ Code

The generated header file will contain:

// Auto-generated variable name (based on filename)
constexpr const char* my_kernel = "...";  // OpenCL source code

// Kernel name array (if kernel functions are detected)
constexpr const char* my_kernel_kernels[] = {
    "kernel_name_1",
    "kernel_name_2"
};
constexpr unsigned int my_kernel_kernel_count = 2;

Requirements

• Bazel 6.0 or higher (with MODULE.bazel support)
• rules_python (automatically included as a dependency)

Rule Reference

opencl_library

Compiles OpenCL source files to C++ header files.

Parameters:

• name (required): Target name
• srcs (required): List of OpenCL source files (.cl files), must contain exactly one file
• include_dirs (optional): List of include directories for #include directives
• var (optional): C++ variable name, derived from filename if not specified
• hdrs (optional): List of .cl header files that may be included by the source file

Output:

• Generates .cl.h header file containing OpenCL source code as C++ string constants

Examples

See test cases in the project for complete examples.