Follow-up fixes

Signed-off-by: Artur Gainullin <artur.gainullin@intel.com>

Author: againull

sycl/doc/EnvironmentVariables.md

@@ -12,7 +12,7 @@ subject to change. Do not rely on these variables in production code.
 | Environment variable | Values | Description |
 | -------------------- | ------ | ----------- |
 | SYCL_PI_TRACE | Described [below](#sycl_pi_trace-options)  | Enable specified level of tracing for PI. |
-| SYCL_BE | PI_OPENCL, PI_CUDA | When SYCL RT is built with PI, force SYCL to consider only devices of the specified backend during the device selection. |
+| SYCL_BE | PI_OPENCL, PI_CUDA | Force SYCL RT to consider only devices of the specified backend during the device selection. |
 | SYCL_DEVICE_TYPE | One of: CPU, GPU, ACC, HOST | Force SYCL to use the specified device type. If unset, default selection rules are applied. If set to any unlisted value, this control has no effect. If the requested device type is not found, a `cl::sycl::runtime_error` exception is thrown. If a non-default device selector is used, a device must satisfy both the selector and this control to be chosen. This control only has effect on devices created with a selector. |
 | SYCL_PROGRAM_COMPILE_OPTIONS | String of valid OpenCL compile options | Override compile options for all programs. |
 | SYCL_PROGRAM_LINK_OPTIONS | String of valid OpenCL link options | Override link options for all programs. |
@@ -41,10 +41,10 @@ SYCL_PRINT_EXECUTION_GRAPH can accept one or more comma separated values from th
 
 ### SYCL_PI_TRACE Options
 
-SYCL_PI_TRACE can accept one of the values from the table below
+SYCL_PI_TRACE accepts a bit-mask. Supported tracing levels are in the table below
 
 | Option | Description |
 | ------ | ----------- |
-| 1 | Enable basic tracing |
+| 1 | Enable basic tracing, which is tracing of PI plugins/devices discovery |
 | 2 | Enable tracing of the PI calls |
-| -1 | Enable all levelis of tracing |
+| -1 | Enable all levels of tracing |

sycl/include/CL/sycl/detail/pi.hpp

@@ -55,8 +55,6 @@ enum TraceLevel {
 // Return true if we want to trace PI related activities.
 bool trace(TraceLevel level);
 
-const char *traceLabel();
-
 #ifdef SYCL_RT_OS_WINDOWS
 #define OPENCL_PLUGIN_NAME "pi_opencl.dll"
 #define CUDA_PLUGIN_NAME "pi_cuda.dll"

sycl/source/detail/config.def

@@ -14,4 +14,4 @@ CONFIG(SYCL_PRINT_EXECUTION_GRAPH, 32, __SYCL_PRINT_EXECUTION_GRAPH)
 CONFIG(SYCL_DISABLE_EXECUTION_GRAPH_CLEANUP, 1, __SYCL_DISABLE_EXECUTION_GRAPH_CLEANUP)
 CONFIG(SYCL_DEVICE_ALLOWLIST, 1024, __SYCL_DEVICE_ALLOWLIST)
 CONFIG(SYCL_BE, 16, __SYCL_BE)
-CONFIG(SYCL_PI_TRACE, 4, __SYCL_PI_TRACE)
+CONFIG(SYCL_PI_TRACE, 16, __SYCL_PI_TRACE)

sycl/source/detail/config.hpp

@@ -106,14 +106,15 @@ template <> class SYCLConfig<SYCL_BE> {
   using BaseT = SYCLConfigBase<SYCL_BE>;
 
 public:
-  static backend get() {
+  static backend *get() {
     static bool Initialized = false;
+    static bool IsSet = false;
     static backend Backend = backend::opencl;
 
     // Configuration parameters are processed only once, like reading a string
     // from environment and converting it into a typed object.
     if (Initialized)
-      return Backend;
+      return IsSet ? &Backend : nullptr;
 
     const char *ValStr = BaseT::getRawValue();
     const std::map<std::string, backend> SyclBeMap{
@@ -124,9 +125,12 @@ template <> class SYCLConfig<SYCL_BE> {
         pi::die("Invalid backend. "
                 "Valid values are PI_OPENCL/PI_CUDA");
       Backend = It->second;
+      Initialized = true;
+      IsSet = true;
+      return &Backend;
     }
     Initialized = true;
-    return Backend;
+    return nullptr;
   }
 };
 

sycl/source/detail/pi.cpp

@@ -195,37 +195,24 @@ bool trace(TraceLevel Level) {
   return (TraceLevelMask & Level) == Level;
 }
 
-const char *traceLabel() {
-  int TraceLevelMask = SYCLConfig<SYCL_PI_TRACE>::get();
-  switch (TraceLevelMask) {
-  case PI_TRACE_BASIC:
-    return "SYCL_PI_TRACE[PI_TRACE_BASIC]: ";
-  case PI_TRACE_CALLS:
-    return "SYCL_PI_TRACE[PI_TRACE_CALLS]: ";
-  case PI_TRACE_ALL:
-    return "SYCL_PI_TRACE[PI_TRACE_ALL]: ";
-  default:
-    assert("Unsupported trace level");
-  }
-  return nullptr;
-}
-
 // Initializes all available Plugins.
 vector_class<plugin> initialize() {
   vector_class<plugin> Plugins;
   vector_class<std::pair<std::string, backend>> PluginNames;
   findPlugins(PluginNames);
 
   if (PluginNames.empty() && trace(PI_TRACE_ALL))
-    std::cerr << traceLabel() << "No Plugins Found." << std::endl;
+    std::cerr << "SYCL_PI_TRACE[all]: "
+              << "No Plugins Found." << std::endl;
 
   PiPlugin PluginInformation;
   for (unsigned int I = 0; I < PluginNames.size(); I++) {
     void *Library = loadPlugin(PluginNames[I].first);
 
     if (!Library) {
       if (trace(PI_TRACE_ALL)) {
-        std::cerr << traceLabel() << "Check if plugin is present. "
+        std::cerr << "SYCL_PI_TRACE[all]: "
+                  << "Check if plugin is present. "
                   << "Failed to load plugin: " << PluginNames[I].first
                   << std::endl;
       }
@@ -234,25 +221,27 @@ vector_class<plugin> initialize() {
 
     if (!bindPlugin(Library, &PluginInformation)) {
       if (trace(PI_TRACE_ALL)) {
-        std::cerr << traceLabel() << "Failed to bind PI APIs to the plugin: "
+        std::cerr << "SYCL_PI_TRACE[all]: "
+                  << "Failed to bind PI APIs to the plugin: "
                   << PluginNames[I].first << std::endl;
       }
       continue;
     }
-    if (SYCLConfig<SYCL_BE>::get() == backend::opencl &&
-        PluginNames[I].first.find("opencl") != std::string::npos) {
+    backend *BE = SYCLConfig<SYCL_BE>::get();
+    if (!BE || (*BE == backend::opencl &&
+                PluginNames[I].first.find("opencl") != std::string::npos)) {
       // Use the OpenCL plugin as the GlobalPlugin
       GlobalPlugin =
           std::make_shared<plugin>(PluginInformation, backend::opencl);
-    }
-    if (SYCLConfig<SYCL_BE>::get() == backend::cuda &&
-        PluginNames[I].first.find("cuda") != std::string::npos) {
+    } else if (*BE == backend::cuda &&
+               PluginNames[I].first.find("cuda") != std::string::npos) {
       // Use the CUDA plugin as the GlobalPlugin
       GlobalPlugin = std::make_shared<plugin>(PluginInformation, backend::cuda);
     }
     Plugins.emplace_back(plugin(PluginInformation, PluginNames[I].second));
     if (trace(TraceLevel::PI_TRACE_BASIC))
-      std::cerr << traceLabel() << "Plugin found and successfully loaded: "
+      std::cerr << "SYCL_PI_TRACE[basic]: "
+                << "Plugin found and successfully loaded: "
                 << PluginNames[I].first << std::endl;
   }
 

sycl/source/device.cpp

@@ -53,12 +53,12 @@ vector_class<device> device::get_devices(info::device_type deviceType) {
     for (const auto &plt : platform::get_platforms()) {
       // If SYCL_BE is set then skip platforms which doesn't have specified
       // backend.
-      if (std::getenv("SYCL_BE")) {
-        if (plt.is_host() ||
-            detail::getSyclObjImpl(plt)->getPlugin().getBackend() !=
-                detail::SYCLConfig<detail::SYCL_BE>::get())
+      backend *ForcedBackend = detail::SYCLConfig<detail::SYCL_BE>::get();
+      if (ForcedBackend)
+        if (!plt.is_host() &&
+            (detail::getSyclObjImpl(plt)->getPlugin().getBackend() !=
+             *ForcedBackend))
           continue;
-      }
       if (includeHost && plt.is_host()) {
         vector_class<device> host_device(
             plt.get_devices(info::device_type::host));

sycl/source/device_selector.cpp

@@ -38,12 +38,12 @@ device device_selector::select_device() const {
       string_class PlatformVersion = dev.get_info<info::device::platform>()
                                          .get_info<info::platform::version>();
       string_class DeviceName = dev.get_info<info::device::name>();
-      std::cout << detail::pi::traceLabel()
+      std::cout << "SYCL_PI_TRACE[all]: "
                 << "select_device(): -> score = " << score << std::endl
-                << detail::pi::traceLabel() << "  platform: " << PlatformVersion
-                << std::endl
-                << detail::pi::traceLabel() << "  device: " << DeviceName
-                << std::endl;
+                << "SYCL_PI_TRACE[all]: "
+                << "  platform: " << PlatformVersion << std::endl
+                << "SYCL_PI_TRACE[all]: "
+                << "  device: " << DeviceName << std::endl;
     }
 
     // SYCL spec says: "If more than one device receives the high score then
@@ -63,11 +63,12 @@ device device_selector::select_device() const {
       string_class PlatformVersion = res->get_info<info::device::platform>()
                                          .get_info<info::platform::version>();
       string_class DeviceName = res->get_info<info::device::name>();
-      std::cout << detail::pi::traceLabel() << "Selected device ->" << std::endl
-                << detail::pi::traceLabel() << "  platform: " << PlatformVersion
-                << std::endl
-                << detail::pi::traceLabel() << "  device: " << DeviceName
-                << std::endl;
+      std::cout << "SYCL_PI_TRACE[all]: "
+                << "Selected device ->" << std::endl
+                << "SYCL_PI_TRACE[all]: "
+                << "  platform: " << PlatformVersion << std::endl
+                << "SYCL_PI_TRACE[all]: "
+                << "  device: " << DeviceName << std::endl;
     }
     return *res;
   }