[SYCL] Do not preload L0 v2 adapter if it's not requested

The adapter sets certain env variables during adapter init.
Preloding it will set those variables and result in
unexpected behavior for the legacy adater.

Author: igchor

sycl/ur_win_proxy_loader/ur_win_proxy_loader.cpp

@@ -107,6 +107,27 @@ void *&getDllHandle() {
   return dllHandle;
 }
 
+static bool shouldLoadL0V2adapter() {
+  auto SyclEnv = std::getenv("SYCL_UR_USE_LEVEL_ZERO_V2");
+  auto UREnv = std::getenv("UR_LOADER_USE_LEVEL_ZERO_V2");
+
+  try {
+    if (SyclEnv && std::stoi(SyclEnv) == 1) {
+      return true;
+    }
+  } catch (...) {
+  }
+
+  try {
+    if (UREnv && std::stoi(UREnv) == 1) {
+      return true;
+    }
+  } catch (...) {
+  }
+
+  return false;
+}
+
 /// Load the adapter libraries
 void preloadLibraries() {
   // Suppress system errors.
@@ -142,7 +163,8 @@ void preloadLibraries() {
   getDllHandle() = loadAdapter(UR_LIBRARY_NAME(loader));
   loadAdapter(UR_LIBRARY_NAME(adapter_opencl));
   loadAdapter(UR_LIBRARY_NAME(adapter_level_zero));
-  loadAdapter(UR_LIBRARY_NAME(adapter_level_zero_v2));
+  if (shouldLoadL0V2adapter())
+    loadAdapter(UR_LIBRARY_NAME(adapter_level_zero_v2));
   loadAdapter(UR_LIBRARY_NAME(adapter_cuda));
   loadAdapter(UR_LIBRARY_NAME(adapter_hip));
   loadAdapter(UR_LIBRARY_NAME(adapter_native_cpu));