[SYCL] Allow overriding plugin libraries (#4067)

Motivation for this change is to provide ability to replay PI traces: a fake plugin opens a file with trace recording and replies to PI calls with info, acquired from that file. This can be used for debugging SYCL applications runtime when target hardware is not available. Such design allows the fake plugin rely on the fact that the library is only loaded once, which makes such a plugin stateless.

Author: Alexander Batashev

sycl/source/detail/config.def

@@ -31,3 +31,7 @@ CONFIG(SYCL_CACHE_THRESHOLD, 16, __SYCL_CACHE_THRESHOLD)
 CONFIG(SYCL_CACHE_MIN_DEVICE_IMAGE_SIZE, 16, __SYCL_CACHE_MIN_DEVICE_IMAGE_SIZE)
 CONFIG(SYCL_CACHE_MAX_DEVICE_IMAGE_SIZE, 16, __SYCL_CACHE_MAX_DEVICE_IMAGE_SIZE)
 CONFIG(INTEL_ENABLE_OFFLOAD_ANNOTATIONS, 1, __SYCL_INTEL_ENABLE_OFFLOAD_ANNOTATIONS)
+CONFIG(SYCL_OVERRIDE_PI_OPENCL, 1024, __SYCL_OVERRIDE_PI_OPENCL)
+CONFIG(SYCL_OVERRIDE_PI_LEVEL_ZERO, 1024, __SYCL_OVERRIDE_PI_LEVEL_ZERO)
+CONFIG(SYCL_OVERRIDE_PI_CUDA, 1024, __SYCL_OVERRIDE_PI_CUDA)
+CONFIG(SYCL_OVERRIDE_PI_ROCM, 1024, __SYCL_OVERRIDE_PI_ROCM)

sycl/source/detail/pi.cpp

@@ -263,19 +263,34 @@ std::string memFlagsToString(pi_mem_flags Flags) {
 std::shared_ptr<plugin> GlobalPlugin;
 
 // Find the plugin at the appropriate location and return the location.
-bool findPlugins(std::vector<std::pair<std::string, backend>> &PluginNames) {
+std::vector<std::pair<std::string, backend>> findPlugins() {
+  std::vector<std::pair<std::string, backend>> PluginNames;
+
   // TODO: Based on final design discussions, change the location where the
   // plugin must be searched; how to identify the plugins etc. Currently the
   // search is done for libpi_opencl.so/pi_opencl.dll file in LD_LIBRARY_PATH
   // env only.
   //
+  const char *OpenCLPluginName =
+      SYCLConfig<SYCL_OVERRIDE_PI_OPENCL>::get()
+          ? SYCLConfig<SYCL_OVERRIDE_PI_OPENCL>::get()
+          : __SYCL_OPENCL_PLUGIN_NAME;
+  const char *L0PluginName =
+      SYCLConfig<SYCL_OVERRIDE_PI_LEVEL_ZERO>::get()
+          ? SYCLConfig<SYCL_OVERRIDE_PI_LEVEL_ZERO>::get()
+          : __SYCL_LEVEL_ZERO_PLUGIN_NAME;
+  const char *CUDAPluginName = SYCLConfig<SYCL_OVERRIDE_PI_CUDA>::get()
+                                   ? SYCLConfig<SYCL_OVERRIDE_PI_CUDA>::get()
+                                   : __SYCL_CUDA_PLUGIN_NAME;
+  const char *ROCMPluginName = SYCLConfig<SYCL_OVERRIDE_PI_ROCM>::get()
+                                   ? SYCLConfig<SYCL_OVERRIDE_PI_ROCM>::get()
+                                   : __SYCL_ROCM_PLUGIN_NAME;
   device_filter_list *FilterList = SYCLConfig<SYCL_DEVICE_FILTER>::get();
   if (!FilterList) {
-    PluginNames.emplace_back(__SYCL_OPENCL_PLUGIN_NAME, backend::opencl);
-    PluginNames.emplace_back(__SYCL_LEVEL_ZERO_PLUGIN_NAME,
-                             backend::level_zero);
-    PluginNames.emplace_back(__SYCL_CUDA_PLUGIN_NAME, backend::cuda);
-    PluginNames.emplace_back(__SYCL_ROCM_PLUGIN_NAME, backend::rocm);
+    PluginNames.emplace_back(OpenCLPluginName, backend::opencl);
+    PluginNames.emplace_back(L0PluginName, backend::level_zero);
+    PluginNames.emplace_back(CUDAPluginName, backend::cuda);
+    PluginNames.emplace_back(ROCMPluginName, backend::rocm);
   } else {
     std::vector<device_filter> Filters = FilterList->get();
     bool OpenCLFound = false;
@@ -286,26 +301,25 @@ bool findPlugins(std::vector<std::pair<std::string, backend>> &PluginNames) {
       backend Backend = Filter.Backend;
       if (!OpenCLFound &&
           (Backend == backend::opencl || Backend == backend::all)) {
-        PluginNames.emplace_back(__SYCL_OPENCL_PLUGIN_NAME, backend::opencl);
+        PluginNames.emplace_back(OpenCLPluginName, backend::opencl);
         OpenCLFound = true;
       }
       if (!LevelZeroFound &&
           (Backend == backend::level_zero || Backend == backend::all)) {
-        PluginNames.emplace_back(__SYCL_LEVEL_ZERO_PLUGIN_NAME,
-                                 backend::level_zero);
+        PluginNames.emplace_back(L0PluginName, backend::level_zero);
         LevelZeroFound = true;
       }
       if (!CudaFound && (Backend == backend::cuda || Backend == backend::all)) {
-        PluginNames.emplace_back(__SYCL_CUDA_PLUGIN_NAME, backend::cuda);
+        PluginNames.emplace_back(CUDAPluginName, backend::cuda);
         CudaFound = true;
       }
       if (!RocmFound && (Backend == backend::rocm || Backend == backend::all)) {
-        PluginNames.emplace_back(__SYCL_ROCM_PLUGIN_NAME, backend::rocm);
+        PluginNames.emplace_back(ROCMPluginName, backend::rocm);
         RocmFound = true;
       }
     }
   }
-  return true;
+  return PluginNames;
 }
 
 // Load the Plugin by calling the OS dependent library loading call.
@@ -359,8 +373,7 @@ const std::vector<plugin> &initialize() {
 }
 
 static void initializePlugins(std::vector<plugin> *Plugins) {
-  std::vector<std::pair<std::string, backend>> PluginNames;
-  findPlugins(PluginNames);
+  std::vector<std::pair<std::string, backend>> PluginNames = findPlugins();
 
   if (PluginNames.empty() && trace(PI_TRACE_ALL))
     std::cerr << "SYCL_PI_TRACE[all]: "

sycl/test/basic_tests/pluign_overrides_negative.cpp

@@ -0,0 +1,16 @@
+// RUN: %clangxx -fsycl %s -o %t.out
+// RUN: env SYCL_OVERRIDE_PI_OPENCL=opencl_test env SYCL_OVERRIDE_PI_LEVEL_ZERO=l0_test env SYCL_OVERRIDE_PI_CUDA=cuda_test env SYCL_OVERRIDE_PI_ROCM=rocm_test env SYCL_PI_TRACE=-1 %t.out > %t.log 2>&1
+// RUN: FileCheck %s --input-file %t.log
+
+#include <sycl/sycl.hpp>
+
+int main() {
+  sycl::queue Q;
+
+  return 0;
+}
+
+// CHECK: SYCL_PI_TRACE[all]: Check if plugin is present. Failed to load plugin: opencl_test
+// CHECK: SYCL_PI_TRACE[all]: Check if plugin is present. Failed to load plugin: l0_test
+// CHECK: SYCL_PI_TRACE[all]: Check if plugin is present. Failed to load plugin: cuda_test
+// CHECK: SYCL_PI_TRACE[all]: Check if plugin is present. Failed to load plugin: rocm_test

sycl/test/basic_tests/pluign_overrides_positive.cpp

@@ -0,0 +1,43 @@
+// RUN: %clangxx -fsycl -DFAKE_PLUGIN -shared %s -o %t_fake_plugin.so
+// RUN: %clangxx -fsycl %s -o %t.out
+// RUN: env SYCL_OVERRIDE_PI_OPENCL=%t_fake_plugin.so env SYCL_OVERRIDE_PI_LEVEL_ZERO=%t_fake_plugin.so env SYCL_OVERRIDE_PI_CUDA=%t_fake_plugin.so env SYCL_OVERRIDE_PI_ROCM=%t_fake_plugin.so env SYCL_PI_TRACE=-1 %t.out > %t.log 2>&1
+// RUN: FileCheck %s --input-file %t.log
+// REQUIRES: linux
+
+#ifdef FAKE_PLUGIN
+
+#include <CL/sycl/detail/pi.h>
+
+pi_result piPlatformsGet(pi_uint32 NumEntries, pi_platform *Platforms,
+                         pi_uint32 *NumPlatforms) {
+  return PI_INVALID_OPERATION;
+}
+
+pi_result piTearDown(void *) { return PI_SUCCESS; }
+
+pi_result piPluginInit(pi_plugin *PluginInit) {
+  PluginInit->PiFunctionTable.piPlatformsGet = piPlatformsGet;
+  PluginInit->PiFunctionTable.piTearDown = piTearDown;
+  return PI_SUCCESS;
+}
+
+#else
+
+#include <sycl/sycl.hpp>
+
+int main() {
+  try {
+    sycl::platform P{sycl::default_selector{}};
+  } catch (...) {
+    // NOP
+  }
+
+  return 0;
+}
+
+#endif
+
+// CHECK: SYCL_PI_TRACE[basic]: Plugin found and successfully loaded: {{[0-9a-zA-Z_\/\.-]+}}_fake_plugin.so
+// CHECK: SYCL_PI_TRACE[basic]: Plugin found and successfully loaded: {{[0-9a-zA-Z_\/\.-]+}}_fake_plugin.so
+// CHECK: SYCL_PI_TRACE[basic]: Plugin found and successfully loaded: {{[0-9a-zA-Z_\/\.-]+}}_fake_plugin.so
+// CHECK: SYCL_PI_TRACE[basic]: Plugin found and successfully loaded: {{[0-9a-zA-Z_\/\.-]+}}_fake_plugin.so