Refactor CUB util_device

Author: bernhardmgruber

cub/cub/util_device.cuh

@@ -155,9 +155,10 @@ CUB_RUNTIME_FUNCTION inline int DeviceCountUncached()
 
 /**
  * \brief Cache for an arbitrary value produced by a nullary function.
+ * deprecated [Since 2.6.0]
  */
 template <typename T, T (*Function)()>
-struct ValueCache
+struct CUB_DEPRECATED ValueCache
 {
   T const value;
 
@@ -170,13 +171,11 @@ struct ValueCache
   {}
 };
 
-// Host code, only safely usable in C++11 or newer, where thread-safe
-// initialization of static locals is guaranteed.  This is a separate function
-// to avoid defining a local static in a host/device function.
+// Host code. This is a separate function to avoid defining a local static in a host/device function.
 _CCCL_HOST inline int DeviceCountCachedValue()
 {
-  static ValueCache<int, DeviceCountUncached> cache;
-  return cache.value;
+  static int count = DeviceCountUncached();
+  return count;
 }
 
 /**
@@ -211,7 +210,7 @@ struct PerDeviceAttributeCache
   // Each entry starts in the `DeviceEntryEmpty` state, then proceeds to the
   // `DeviceEntryInitializing` state, and then proceeds to the
   // `DeviceEntryReady` state. These are the only state transitions allowed;
-  // e.g. a linear sequence of transitions.
+  // i.e. a linear sequence of transitions.
   enum DeviceEntryStatus
   {
     DeviceEntryEmpty = 0,
@@ -372,7 +371,6 @@ _CCCL_HOST inline cudaError_t PtxVersionUncached(int& ptx_version, int device)
 template <typename Tag>
 _CCCL_HOST inline PerDeviceAttributeCache& GetPerDeviceAttributeCache()
 {
-  // C++11 guarantees that initialization of static locals is thread safe.
   static PerDeviceAttributeCache cache;
   return cache;
 }
@@ -392,8 +390,7 @@ struct SmVersionCacheTag
 _CCCL_HOST inline cudaError_t PtxVersion(int& ptx_version, int device)
 {
   auto const payload = GetPerDeviceAttributeCache<PtxVersionCacheTag>()(
-    // If this call fails, then we get the error code back in the payload,
-    // which we check with `CubDebug` below.
+    // If this call fails, then we get the error code back in the payload, which we check with `CubDebug` below.
     [=](int& pv) {
       return PtxVersionUncached(pv, device);
     },
@@ -417,23 +414,10 @@ _CCCL_HOST inline cudaError_t PtxVersion(int& ptx_version, int device)
 CUB_RUNTIME_FUNCTION inline cudaError_t PtxVersion(int& ptx_version)
 {
   cudaError_t result = cudaErrorUnknown;
-  NV_IF_TARGET(
-    NV_IS_HOST,
-    (auto const device  = CurrentDevice();
-     auto const payload = GetPerDeviceAttributeCache<PtxVersionCacheTag>()(
-       // If this call fails, then we get the error code back in the payload,
-       // which we check with `CubDebug` below.
-       [=](int& pv) {
-         return PtxVersionUncached(pv, device);
-       },
-       device);
-
-     if (!CubDebug(payload.error)) { ptx_version = payload.attribute; }
-
-     result = payload.error;),
-    ( // NV_IS_DEVICE:
-      result = PtxVersionUncached(ptx_version);));
-
+  NV_IF_TARGET(NV_IS_HOST,
+               (result = PtxVersion(ptx_version, CurrentDevice());),
+               ( // NV_IS_DEVICE:
+                 result = PtxVersionUncached(ptx_version);));
   return result;
 }
 
@@ -477,8 +461,7 @@ CUB_RUNTIME_FUNCTION inline cudaError_t SmVersion(int& sm_version, int device =
   NV_IF_TARGET(
     NV_IS_HOST,
     (auto const payload = GetPerDeviceAttributeCache<SmVersionCacheTag>()(
-       // If this call fails, then we get the error code back in
-       // the payload, which we check with `CubDebug` below.
+       // If this call fails, then we get the error code back in the payload, which we check with `CubDebug` below.
        [=](int& pv) {
          return SmVersionUncached(pv, device);
        },
@@ -565,9 +548,8 @@ CUB_RUNTIME_FUNCTION inline cudaError_t DebugSyncStream(cudaStream_t stream)
 CUB_RUNTIME_FUNCTION inline cudaError_t HasUVA(bool& has_uva)
 {
   has_uva           = false;
-  cudaError_t error = cudaSuccess;
   int device        = -1;
-  error             = CubDebug(cudaGetDevice(&device));
+  cudaError_t error = CubDebug(cudaGetDevice(&device));
   if (cudaSuccess != error)
   {
     return error;