Cycles: OpenCL Separate Compilation Debug Flag

OpenCL Parallel compilation only works inside Blender. When using cycles in a different setup (standaline or other software) it failed compiling kernels as they don't have the appropriate Python API and command line arguments.

This change introduces a `running_inside_blender` debug flag, that triggers out of process compilation of the kernels. Compilation still happens in subthread that enabled the preview kernels and compilation of the kernels during BVH building

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5439

intern/cycles/blender/CMakeLists.txt

@@ -68,7 +68,7 @@ set(ADDON_FILES
 add_definitions(${GL_DEFINITIONS})
 
 if(WITH_CYCLES_DEVICE_OPENCL)
-    add_definitions(-DWITH_OPENCL)
+  add_definitions(-DWITH_OPENCL)
 endif()
 
 if(WITH_CYCLES_NETWORK)

intern/cycles/blender/blender_python.cpp

@@ -177,6 +177,8 @@ static PyObject *init_func(PyObject * /*self*/, PyObject *args)
 
   BlenderSession::headless = headless;
 
+  DebugFlags().running_inside_blender = true;
+
   VLOG(2) << "Debug flags initialized to:\n" << DebugFlags();
 
   Py_RETURN_NONE;

intern/cycles/device/opencl/opencl_split.cpp

@@ -676,7 +676,7 @@ OpenCLDevice::OpenCLDevice(DeviceInfo &info, Stats &stats, Profiler &profiler, b
   device_initialized = true;
 
   split_kernel = new OpenCLSplitKernel(this);
-  if (!background) {
+  if (use_preview_kernels) {
     load_preview_kernels();
   }
 }

intern/cycles/device/opencl/opencl_util.cpp

@@ -619,15 +619,16 @@ void OpenCLDevice::OpenCLProgram::compile()
       debug_src = &clsrc;
     }
 
-    /* If binary kernel exists already, try use it. */
-    if (compile_separate(clbin)) {
+    if (DebugFlags().running_inside_blender && compile_separate(clbin)) {
       add_log(string("Built and loaded program from ") + clbin + ".", true);
       loaded = true;
     }
     else {
-      add_log(string("Separate-process building of ") + clbin +
-                  " failed, will fall back to regular building.",
-              true);
+      if (DebugFlags().running_inside_blender) {
+        add_log(string("Separate-process building of ") + clbin +
+                    " failed, will fall back to regular building.",
+                true);
+      }
 
       /* If does not exist or loading binary failed, compile kernel. */
       if (!compile_kernel(debug_src)) {

intern/cycles/util/util_debug.cpp

@@ -120,7 +120,7 @@ void DebugFlags::OpenCL::reset()
   debug = (getenv("CYCLES_OPENCL_DEBUG") != NULL);
 }
 
-DebugFlags::DebugFlags() : viewport_static_bvh(false)
+DebugFlags::DebugFlags() : viewport_static_bvh(false), running_inside_blender(false)
 {
   /* Nothing for now. */
 }

intern/cycles/util/util_debug.h

@@ -33,6 +33,8 @@ class DebugFlags {
   /* Use static BVH in viewport, to match final render exactly. */
   bool viewport_static_bvh;
 
+  bool running_inside_blender;
+
   /* Descriptor of CPU feature-set to be used. */
   struct CPU {
     CPU();