[SYCL] Guard access to the cache of device lib programs (#6094)

We cache device library programs (like fallback assertion) in the
context. In multi-threaded applications simultaneous access to the
cache of device lib programs is possible in program_manager::build().
That's why access to the this cache needs to be guarded to avoid data
race.

Author: againull

sycl/source/detail/context_impl.hpp

@@ -140,6 +140,9 @@ class context_impl {
   /// reference.
   const std::vector<device> &getDevices() const { return MDevices; }
 
+  using CachedLibProgramsT =
+      std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram>;
+
   /// In contrast to user programs, which are compiled from user code, library
   /// programs come from the SYCL runtime. They are identified by the
   /// corresponding extension:
@@ -151,10 +154,10 @@ class context_impl {
   /// See `doc/design/DeviceLibExtensions.rst' for
   /// more details.
   ///
-  /// \returns a map with device library programs.
-  std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram> &
-  getCachedLibPrograms() {
-    return MCachedLibPrograms;
+  /// \returns an instance of sycl::detail::Locked which wraps a map with device
+  /// library programs and the corresponding lock for synchronized access.
+  Locked<CachedLibProgramsT> acquireCachedLibPrograms() {
+    return {MCachedLibPrograms, MCachedLibProgramsMutex};
   }
 
   KernelProgramCache &getKernelProgramCache() const;
@@ -179,8 +182,8 @@ class context_impl {
   PlatformImplPtr MPlatform;
   property_list MPropList;
   bool MHostContext;
-  std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram>
-      MCachedLibPrograms;
+  CachedLibProgramsT MCachedLibPrograms;
+  std::mutex MCachedLibProgramsMutex;
   mutable KernelProgramCache MKernelProgramCache;
   mutable PropertySupport MSupportBufferLocationByDevices;
 };

sycl/source/detail/program_manager/program_manager.cpp

@@ -567,8 +567,7 @@ RT::PiProgram ProgramManager::getBuiltPIProgram(
 
     ProgramPtr BuiltProgram =
         build(std::move(ProgramManaged), ContextImpl, CompileOpts, LinkOpts,
-              getRawSyclObjImpl(Device)->getHandleRef(),
-              ContextImpl->getCachedLibPrograms(), DeviceLibReqMask);
+              getRawSyclObjImpl(Device)->getHandleRef(), DeviceLibReqMask);
 
     emitBuiltProgramInfo(BuiltProgram.get(), ContextImpl);
 
@@ -779,13 +778,14 @@ static const char *getDeviceLibExtensionStr(DeviceLibExt Extension) {
                               PI_INVALID_OPERATION);
 }
 
-static RT::PiProgram loadDeviceLibFallback(
-    const ContextImplPtr Context, DeviceLibExt Extension,
-    const RT::PiDevice &Device,
-    std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram>
-        &CachedLibPrograms) {
+static RT::PiProgram loadDeviceLibFallback(const ContextImplPtr Context,
+                                           DeviceLibExt Extension,
+                                           const RT::PiDevice &Device) {
 
   const char *LibFileName = getDeviceLibFilename(Extension);
+
+  auto LockedCache = Context->acquireCachedLibPrograms();
+  auto CachedLibPrograms = LockedCache.get();
   auto CacheResult = CachedLibPrograms.emplace(
       std::make_pair(std::make_pair(Extension, Device), nullptr));
   bool Cached = !CacheResult.second;
@@ -923,11 +923,9 @@ static bool isDeviceLibRequired(DeviceLibExt Ext, uint32_t DeviceLibReqMask) {
   return ((DeviceLibReqMask & Mask) == Mask);
 }
 
-static std::vector<RT::PiProgram> getDeviceLibPrograms(
-    const ContextImplPtr Context, const RT::PiDevice &Device,
-    std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram>
-        &CachedLibPrograms,
-    uint32_t DeviceLibReqMask) {
+static std::vector<RT::PiProgram>
+getDeviceLibPrograms(const ContextImplPtr Context, const RT::PiDevice &Device,
+                     uint32_t DeviceLibReqMask) {
   std::vector<RT::PiProgram> Programs;
 
   std::pair<DeviceLibExt, bool> RequiredDeviceLibExt[] = {
@@ -975,21 +973,18 @@ static std::vector<RT::PiProgram> getDeviceLibPrograms(
     bool DeviceSupports = DevExtList.npos != DevExtList.find(ExtStr);
 
     if (!DeviceSupports || InhibitNativeImpl) {
-      Programs.push_back(
-          loadDeviceLibFallback(Context, Ext, Device, CachedLibPrograms));
+      Programs.push_back(loadDeviceLibFallback(Context, Ext, Device));
       FallbackIsLoaded = true;
     }
   }
   return Programs;
 }
 
-ProgramManager::ProgramPtr ProgramManager::build(
-    ProgramPtr Program, const ContextImplPtr Context,
-    const std::string &CompileOptions, const std::string &LinkOptions,
-    const RT::PiDevice &Device,
-    std::map<std::pair<DeviceLibExt, RT::PiDevice>, RT::PiProgram>
-        &CachedLibPrograms,
-    uint32_t DeviceLibReqMask) {
+ProgramManager::ProgramPtr
+ProgramManager::build(ProgramPtr Program, const ContextImplPtr Context,
+                      const std::string &CompileOptions,
+                      const std::string &LinkOptions,
+                      const RT::PiDevice &Device, uint32_t DeviceLibReqMask) {
 
   if (DbgProgMgr > 0) {
     std::cerr << ">>> ProgramManager::build(" << Program.get() << ", "
@@ -1008,8 +1003,7 @@ ProgramManager::ProgramPtr ProgramManager::build(
 
   std::vector<RT::PiProgram> LinkPrograms;
   if (LinkDeviceLibs) {
-    LinkPrograms = getDeviceLibPrograms(Context, Device, CachedLibPrograms,
-                                        DeviceLibReqMask);
+    LinkPrograms = getDeviceLibPrograms(Context, Device, DeviceLibReqMask);
   }
 
   static const char *ForceLinkEnv = std::getenv("SYCL_FORCE_LINK");
@@ -1899,8 +1893,7 @@ device_image_plain ProgramManager::build(const device_image_plain &DeviceImage,
 
     ProgramPtr BuiltProgram =
         build(std::move(ProgramManaged), ContextImpl, CompileOpts, LinkOpts,
-              getRawSyclObjImpl(Devs[0])->getHandleRef(),
-              ContextImpl->getCachedLibPrograms(), DeviceLibReqMask);
+              getRawSyclObjImpl(Devs[0])->getHandleRef(), DeviceLibReqMask);
 
     emitBuiltProgramInfo(BuiltProgram.get(), ContextImpl);
 

sycl/source/detail/program_manager/program_manager.hpp

@@ -261,8 +261,6 @@ class ProgramManager {
   ProgramPtr build(ProgramPtr Program, const ContextImplPtr Context,
                    const std::string &CompileOptions,
                    const std::string &LinkOptions, const RT::PiDevice &Device,
-                   std::map<std::pair<DeviceLibExt, RT::PiDevice>,
-                            RT::PiProgram> &CachedLibPrograms,
                    uint32_t DeviceLibReqMask);
   /// Provides a new kernel set id for grouping kernel names together
   KernelSetId getNextKernelSetId() const;