Fixed caching of OpenCL.dll

Author: mmzakhar

.azure-pipelines.yml

@@ -121,17 +121,25 @@ jobs:
       key: '"install" | "$(WINDOWS_BASEKIT_URL)" | "$(WINDOWS_DPCPP_COMPONENTS)" | "tbb" | scripts/cache_exclude_windows.sh'
   - task: Cache@2
     inputs:
-      path: C:\Windows\System32\OpenCL.dll
-      key: '"install" | "$(WINDOWS_BASEKIT_URL)" | "$(WINDOWS_DPCPP_COMPONENTS)" | "opencl" | scripts/cache_exclude_windows.sh'
+      path: opencl # caching of individual files is not supported, caching OpenCL.dll in a folder as a workaround.
+      key: '"install" | "$(WINDOWS_BASEKIT_URL)" | "$(WINDOWS_DPCPP_COMPONENTS)" | "opencl_folder" | scripts/cache_exclude_windows.sh'
       cacheHitVar: CACHE_RESTORED
   - script: scripts/install_windows.bat $(WINDOWS_BASEKIT_URL) $(WINDOWS_DPCPP_COMPONENTS)
     displayName: install
     condition: ne(variables.CACHE_RESTORED, 'true')
+  - bash: cp opencl/OpenCL.dll C:/Windows/System32/
+    displayName: restore OpenCL.dll from cache
+    condition: eq(variables.CACHE_RESTORED, 'true')
   - script: scripts/build_windows.bat dpc++
     displayName: build
   - bash: scripts/cache_exclude_windows.sh
     displayName: exclude unused files from cache
     condition: ne(variables.CACHE_RESTORED, 'true')
+  - bash: |
+      mkdir -p opencl
+      cp C:/Windows/System32/OpenCL.dll opencl/
+    displayName: copy OpenCL.dll to a folder for caching
+    condition: ne(variables.CACHE_RESTORED, 'true')
 
   # Delete the following if you don't want to save install logs
   - task: CopyFiles@2