feat(opencl): add optional OpenCL backend support via Cargo feature

llama-cpp-2/Cargo.toml

@@ -32,6 +32,7 @@ sampler = []
 # Only has an impact on Android.
 android-shared-stdcxx = ["llama-cpp-sys-2/shared-stdcxx"]
 mtmd = ["llama-cpp-sys-2/mtmd"]
+opencl = ["llama-cpp-sys-2/opencl"]
 
 
 [target.'cfg(all(target_os = "macos", any(target_arch = "aarch64", target_arch = "arm64")))'.dependencies]

llama-cpp-sys-2/Cargo.toml

@@ -39,6 +39,7 @@ include = [
     "/llama.cpp/ggml/src/ggml-cuda/**/*",
     "/llama.cpp/ggml/src/ggml-metal/**/*",
     "/llama.cpp/ggml/src/ggml-vulkan/**/*",
+    "/llama.cpp/ggml/src/ggml-opencl/**/*",
 
     "/llama.cpp/ggml/src/llamafile/sgemm.h",
     "/llama.cpp/ggml/src/llamafile/sgemm.cpp",
@@ -81,3 +82,4 @@ openmp = []
 # Only has an impact on Android.
 shared-stdcxx = []
 mtmd = []
+opencl = []

llama-cpp-sys-2/README.md

@@ -1,5 +1,5 @@
 # llama-cpp-sys
 
-Raw bindings to llama.cpp with cuda support.
+Raw bindings to llama.cpp with cuda and opencl support.
 
 See [llama-cpp-2](https://crates.io/crates/llama-cpp-2) for a safe API.

llama-cpp-sys-2/build.rs

@@ -625,6 +625,27 @@ fn main() {
         }
     }
 
+    // OpenCL backend
+    if cfg!(feature = "opencl") {
+        config.define("GGML_OPENCL", "ON");
+        // Explicit for clarity; upstream defaults are ON
+        config.define("GGML_OPENCL_USE_ADRENO_KERNELS", "ON");
+        config.define("GGML_OPENCL_EMBED_KERNELS", "ON");
+
+        match target_os {
+            TargetOs::Apple(_) => {
+                println!("cargo:rustc-link-lib=framework=OpenCL");
+            }
+            TargetOs::Windows(_) => {
+                println!("cargo:rustc-link-lib=OpenCL");
+            }
+            TargetOs::Linux | TargetOs::Android => {
+                println!("cargo:rustc-link-lib=OpenCL");
+            }
+            _ => (),
+        }
+    }
+
     // Android doesn't have OpenMP support AFAICT and openmp is a default feature. Do this here
     // rather than modifying the defaults in Cargo.toml just in case someone enables the OpenMP feature
     // and tries to build for Android anyway.