Adding support for Ascend NPU (#372)

* Adding support for Ascend NPU

* remove the unnecessary hack code

* test more dtype

* npu doesn't support calling torch.allclose with bf16 for now

bindings/python/src/lib.rs

@@ -220,6 +220,7 @@ enum Device {
     Cpu,
     Cuda(usize),
     Mps,
+    Npu(usize),
 }
 
 impl<'source> FromPyObject<'source> for Device {
@@ -229,6 +230,7 @@ impl<'source> FromPyObject<'source> for Device {
                 "cpu" => Ok(Device::Cpu),
                 "cuda" => Ok(Device::Cuda(0)),
                 "mps" => Ok(Device::Mps),
+                "npu" => Ok(Device::Npu(0)),
                 name if name.starts_with("cuda:") => {
                     let tokens: Vec<_> = name.split(':').collect();
                     if tokens.len() == 2 {
@@ -240,6 +242,17 @@ impl<'source> FromPyObject<'source> for Device {
                         )))
                     }
                 }
+                name if name.starts_with("npu:") => {
+                    let tokens: Vec<_> = name.split(':').collect();
+                    if tokens.len() == 2 {
+                        let device: usize = tokens[1].parse()?;
+                        Ok(Device::Npu(device))
+                    } else {
+                        Err(SafetensorError::new_err(format!(
+                            "device {name} is invalid"
+                        )))
+                    }
+                }
                 name => Err(SafetensorError::new_err(format!(
                     "device {name} is invalid"
                 ))),
@@ -258,6 +271,7 @@ impl IntoPy<PyObject> for Device {
             Device::Cpu => "cpu".into_py(py),
             Device::Cuda(n) => format!("cuda:{n}").into_py(py),
             Device::Mps => "mps".into_py(py),
+            Device::Npu(n) => format!("npu:{n}").into_py(py),
         }
     }
 }

bindings/python/tests/test_pt_comparison.py

@@ -7,6 +7,14 @@
 from safetensors.torch import load, load_file, save, save_file
 
 
+try:
+    import torch_npu  # noqa
+
+    npu_present = True
+except Exception:
+    npu_present = False
+
+
 class TorchTestCase(unittest.TestCase):
     def test_serialization(self):
         data = torch.zeros((2, 2), dtype=torch.int32)
@@ -119,6 +127,19 @@ def test_gpu(self):
         reloaded = load_file(local)
         self.assertTrue(torch.equal(torch.arange(4).view((2, 2)), reloaded["test"]))
 
+    @unittest.skipIf(not npu_present, "Npu is not available")
+    def test_npu(self):
+        data = {
+            "test1": torch.zeros((2, 2), dtype=torch.float32).to("npu:0"),
+            "test2": torch.zeros((2, 2), dtype=torch.float16).to("npu:0"),
+        }
+        local = "./tests/data/out_safe_pt_mmap_small_npu.safetensors"
+        save_file(data, local)
+
+        reloaded = load_file(local, device="npu:0")
+        for k, v in reloaded.items():
+            self.assertTrue(torch.allclose(data[k], reloaded[k]))
+
     def test_sparse(self):
         data = {"test": torch.sparse_coo_tensor(size=(2, 3))}
         local = "./tests/data/out_safe_pt_sparse.safetensors"