fix typo and register frontend

cmake/Dependencies.cmake

@@ -1154,7 +1154,7 @@ endif()
 if(USE_XCCL)
   if(NOT USE_XPU)
     message(WARNING
-        "Not using XPU, so disabling USE_NUSE_XCCLCCL. Suppress this warning with "
+        "Not using XPU, so disabling USE_XCCL. Suppress this warning with "
         "-DUSE_XCCL=OFF.")
     caffe2_update_option(USE_XCCL OFF)
   elseif(NOT CMAKE_SYSTEM_NAME STREQUAL "Linux")

cmake/Modules/FindXCCL.cmake

@@ -27,7 +27,7 @@ find_file(
   NO_DEFAULT_PATH
 )
 
-# Find include/sycl path from include path.
+# Find include/oneapi path from include path.
 find_file(
   XCCL_INCLUDE_ONEAPI_DIR
   NAMES oneapi

torch/distributed/distributed_c10d.py

@@ -130,6 +130,7 @@
 _NCCL_AVAILABLE = True
 _GLOO_AVAILABLE = True
 _UCC_AVAILABLE = True
+_XCCL_AVAILABLE = True
 
 _pickler = pickle.Pickler
 _unpickler = pickle.Unpickler
@@ -193,6 +194,14 @@ def _export_c_types() -> None:
 except ImportError:
     _UCC_AVAILABLE = False
 
+try:
+    from torch._C._distributed_c10d import ProcessGroupXCCL
+
+    ProcessGroupXCCL.__module__ = "torch.distributed.distributed_c10d"
+    __all__ += ["ProcessGroupXCCL"]
+except ImportError:
+    _XCCL_AVAILABLE = False
+
 logger = logging.getLogger(__name__)
 
 PG_WRAPPER_STORE_PREFIX = "pg_wrapper"
@@ -222,7 +231,7 @@ class Backend(str):
     """
     An enum-like class for backends.
 
-    Available backends: GLOO, NCCL, UCC, MPI, and other registered backends.
+    Available backends: GLOO, NCCL, UCC, MPI, XCCL, and other registered backends.
 
     The values of this class are lowercase strings, e.g., ``"gloo"``. They can
     be accessed as attributes, e.g., ``Backend.NCCL``.
@@ -242,6 +251,7 @@ class Backend(str):
     NCCL = "nccl"
     UCC = "ucc"
     MPI = "mpi"
+    XCCL = "XCCL"
 
     _BackendPlugin = namedtuple("_BackendPlugin", ["creator_fn", "extended_api"])
 
@@ -1097,6 +1107,9 @@ def is_ucc_available() -> bool:
     """Check if the UCC backend is available."""
     return _UCC_AVAILABLE
 
+def is_xccl_available() -> bool:
+    """Check if the XCCL backend is available."""
+    return _XCCL_AVAILABLE
 
 def is_backend_available(backend: str) -> bool:
     """
@@ -1385,7 +1398,7 @@ def init_process_group(
 
     Args:
         backend (str or Backend, optional): The backend to use. Depending on
-            build-time configurations, valid values include ``mpi``, ``gloo``,
+            build-time configurations, valid values include ``mpi``, ``gloo``, ``xccl``,
             ``nccl``, and ``ucc``. If the backend is not provided, then both a ``gloo``
             and ``nccl`` backend will be created, see notes below for how multiple
             backends are managed. This field can be given as a lowercase string
@@ -1762,7 +1775,6 @@ def _new_process_group_helper(
                 pg_options = ProcessGroupNCCL.Options()
                 pg_options.is_high_priority_stream = False
             pg_options._timeout = timeout
-
             if split_from:
                 pg_options.split_from = split_from
                 pg_options.split_color = _process_group_color(global_ranks_in_group)
@@ -1781,6 +1793,17 @@ def _new_process_group_helper(
                 backend_prefix_store, group_rank, group_size, timeout=timeout
             )
             backend_type = ProcessGroup.BackendType.UCC
+        elif backend_str == Backend.XCCL:
+            if not is_xccl_available():
+                raise RuntimeError("Distributed package doesn't have XCCL built in")
+            if pg_options is not None:
+                assert isinstance(
+                    pg_options, ProcessGroupXCCL.Options
+                ), "Expected pg_options argument to be of type ProcessGroupXCCL.Options"
+            backend_class = ProcessGroupXCCL(
+                backend_prefix_store, group_rank, group_size
+            )
+            backend_type = ProcessGroup.BackendType.XCCL
         else:
             assert (
                 backend_str.upper() in Backend._plugins