add option to force to build in a separate thread

README.md

@@ -527,6 +527,11 @@ using the name of the corresponding environment variable.
 * `CLVK_DEVICE_EXTENSIONS` specifies extensions to be added to the list of
   exposed extensions. It expects a whitespace separated list of extensions.
 
+* `CLVK_BUILD_IN_SEPARATE_THREAD` force to build kernels in a separate thread
+  (default: false). It brings a slight overhead when creating the thread, but
+  can be a work-around when having issues with clang compiling in the
+  application thread.
+
 # Limitations
 
 * Only one device per CL context

src/config.def

@@ -29,6 +29,8 @@ OPTION(uint32_t, printf_buffer_size, 1024*1024u)
 
 OPTION(uint32_t, opencl_version, (uint32_t)CL_MAKE_VERSION(3, 0, 0))
 
+OPTION(bool, build_in_separate_thread, false)
+
 #if COMPILER_AVAILABLE
 OPTION(std::string, clspv_options, "")
 #if !CLSPV_ONLINE_COMPILER

src/program.cpp

@@ -1515,8 +1515,6 @@ bool cvk_program::check_capabilities(const cvk_device* device) const {
 }
 
 void cvk_program::do_build() {
-    cvk_set_current_thread_name_if_supported("clvk-build");
-
     // Destroy entry points from previous build
     m_entry_points.clear();
 
@@ -1682,12 +1680,24 @@ cl_int cvk_program::build(build_operation operation, cl_uint num_devices,
     m_operation_callback_data = data;
 
     cl_int ret = CL_SUCCESS;
-    if (cb) {
+    bool build_in_separate_thread = config.build_in_separate_thread() || cb;
+    bool wait_for_completion = !cb;
+    if (build_in_separate_thread) {
         // Kick off build
-        m_thread = std::make_unique<std::thread>(&cvk_program::do_build, this);
-        m_thread->detach();
+        m_thread = std::make_unique<std::thread>(
+            &cvk_program::do_build_in_separate_thread, this);
+        if (!wait_for_completion) {
+            m_thread->detach();
+        }
     } else {
         do_build();
+    }
+
+    if (wait_for_completion) {
+        if (build_in_separate_thread) {
+            CVK_ASSERT(m_thread->joinable());
+            m_thread->join();
+        }
         if (build_status() != CL_BUILD_SUCCESS) {
             switch (operation) {
             case build_operation::link:

src/program.hpp

@@ -34,6 +34,7 @@
 #include "memory.hpp"
 #include "objects.hpp"
 #include "printf.hpp"
+#include "utils.hpp"
 
 const int SPIR_WORD_SIZE = 4;
 
@@ -855,6 +856,10 @@ struct cvk_program : public _cl_program, api_object<object_magic::program> {
 
 private:
     void do_build();
+    void do_build_in_separate_thread() {
+        cvk_set_current_thread_name_if_supported("clvk-build");
+        do_build();
+    };
     std::string prepare_build_options(const cvk_device* device) const;
     CHECK_RETURN cl_build_status do_build_inner(const cvk_device* device);