Add gpu sniffing program to OpenCL platform cmake configuration process,

to avoid running OpenCL tests on build machines with OpenCL installed, but no GPU.

platforms/opencl/CMakeLists.txt

@@ -19,7 +19,52 @@ IF (APPLE)
    SET (CMAKE_C_FLAGS "-arch i386")
 ENDIF (APPLE)
 
-SUBDIRS (tests)
+# Only run tests if this machine has a OpenCL-capable GPU
+# So run a little test program at configuration time to sniff for GPUs
+# But first, we need to set DYLD_LIBRARY_PATH here.
+get_filename_component(OPENCL_LIB_DIR "${OPENCL_LIBRARY}" PATH)
+file(TO_NATIVE_PATH "${OPENCL_LIB_DIR}" OPENCL_LIB_NATIVE_DIR)
+if(APPLE)
+        set(ENV{DYLD_LIBRARY_PATH} "$ENV{DYLD_LIBRARY_PATH}:${OPENCL_LIB_NATIVE_DIR}")
+elseif(UNIX)
+        set(ENV{LD_LIBRARY_PATH} "$ENV{LD_LIBRARY_PATH}:${OPENCL_LIB_NATIVE_DIR}")
+elseif(MSVC)
+        set(ENV{PATH} "$ENV{PATH};${OPENCL_LIB_NATIVE_DIR}")
+endif(APPLE)
+try_run(RUN_RESULT_VAR COMPILE_RESULT_VAR
+    ${CMAKE_BINARY_DIR} 
+    ${CMAKE_CURRENT_SOURCE_DIR}/tests/has_opencl_gpu.c
+    CMAKE_FLAGS 
+        -DINCLUDE_DIRECTORIES:STRING=${OPENCL_INCLUDE_DIR}
+        -DLINK_LIBRARIES:STRING=${OPENCL_LIBRARY}
+    COMPILE_OUTPUT_VARIABLE COMPILE_OUTPUT_VAR
+    RUN_OUTPUT_VARIABLE RUN_OUTPUT_VAR
+)
+# message("${RUN_OUTPUT_VAR}") # Display number of GPUs found
+# COMPILE_RESULT_VAR is TRUE when compile succeeds
+# RUN_RESULT_VAR is zero when a GPU is found
+set(OPENCL_HAVE_GPU_MAYBE TRUE)
+if(NOT COMPILE_RESULT_VAR)
+    set(OPENCL_HAVE_GPU_MAYBE FALSE)
+endif(NOT COMPILE_RESULT_VAR)
+if(RUN_RESULT_VAR)
+    set(OPENCL_HAVE_GPU_MAYBE FALSE)
+endif(RUN_RESULT_VAR)
+if(OPENCL_HAVE_GPU_MAYBE)
+    set(OPENCL_HAVE_GPU TRUE CACHE BOOL "Whether OpenCL-capable GPU is present")
+    # Remain silent in case where GPU is found.
+    # message("GPU check succeeded")
+    # message("${COMPILE_OUTPUT_VAR}")
+    # message("${RUN_OUTPUT_VAR}")
+else(OPENCL_HAVE_GPU_MAYBE)
+    set(OPENCL_HAVE_GPU FALSE CACHE BOOL "Whether OpenCL-capable GPU is present")
+    message("OpenCL GPU check failed")
+    message("${COMPILE_OUTPUT_VAR}")
+    message("${RUN_OUTPUT_VAR}")
+endif(OPENCL_HAVE_GPU_MAYBE)
+if(OPENCL_HAVE_GPU)
+    SUBDIRS (tests)
+endif(OPENCL_HAVE_GPU)
 
 # The source is organized into subdirectories, but we handle them all from
 # this CMakeLists file rather than letting CMake visit them as SUBDIRS.

platforms/opencl/tests/has_opencl_gpu.c

+/* 
+ * file has_opencl_gpu.c 
+ * created May 6, 2010
+ * by Christopher Bruns
+ * Returns zero if an OpenCL-capable GPU is found.
+ * Returns one otherwise.
+ */
+
+#if defined(__APPLE__) || defined(__MACOSX)
+#include <OpenCL/cl.h>
+#else
+#include <CL/cl.h>
+#endif
+
+#include <stdio.h>
+
+/* 
+ * check_devices() looks for a GPU among all OpenCL devices 
+ * in a particular OpenCL platform.
+ * Returns zero if a GPU is found.  Returns one otherwise.
+ */
+int check_devices(cl_platform_id platform_id) 
+{
+    cl_int err;
+    cl_device_id devices[10];
+    cl_uint num_devices;
+    size_t d;
+    char dname[500];
+    size_t namesize;
+    
+    err = clGetDeviceIDs(platform_id, CL_DEVICE_TYPE_GPU, 10, devices, &num_devices);
+    if (err != CL_SUCCESS) {
+        printf("clGetDeviceIDs error: %d", err);
+        switch(err) {
+            case CL_INVALID_PLATFORM :
+                printf(" INVALID_PLATFORM; platform is not a valid platform.\n");
+                break;
+            case CL_INVALID_DEVICE_TYPE :
+                printf(" CL_INVALID_DEVICE_TYPE; device_type is not a valid value.\n");
+                break;
+            case CL_INVALID_VALUE :
+                printf(" CL_INVALID_VALUE; num_entries is equal to zero and device_type is not NULL or if both num_devices and device_type  are NULL.\n");
+                break;
+            case CL_DEVICE_NOT_FOUND :
+                printf(" CL_DEVICE_NOT_FOUND; no OpenCL devices that matched device_type were found.\n");
+                break;
+            default :
+                printf(" unrecognized error code '%d'\n", err);
+                break;
+        }
+        return 1;
+    }
+    printf("%d devices found\n", num_devices);
+    if (num_devices < 1)
+        return 1;
+    for (d = 0; d < num_devices; ++d) {
+        clGetDeviceInfo(devices[d], CL_DEVICE_NAME, 500, dname, &namesize);
+        printf("Device #%d name = %s\n", d, dname);
+    }
+    return 0;
+}
+
+int main(int argc, char** argv) 
+{
+    size_t p;
+    cl_int err;
+    cl_platform_id platforms[10];
+    cl_uint num_platforms;
+    int status;
+
+    /* Investigate all valid platform IDs */
+    err = clGetPlatformIDs(10, platforms, &num_platforms);
+    if (num_platforms < 1) {
+        printf("No OpenCL platforms found.\n");
+        return 1;
+    }
+    for (p = 0; p < num_platforms; ++p) {
+        printf("Checking platform ID %d\n", p);
+        status = check_devices(platforms[p]);
+        if (status == 0)
+            return status; // found GPU
+    }
+    return 1; // did NOT find GPU
+}