[AMD] Speed up DSV4 MoE weight loading from mmap views (#32315)

test/registered/unit/layers/moe/test_copy_weight_views_before_h2d.py

@@ -0,0 +1,50 @@
+import torch
+
+from sglang.srt.layers.moe.fused_moe_triton.layer import (
+    _copy_weight_view_before_h2d,
+)
+from sglang.test.ci.ci_register import register_cpu_ci
+
+register_cpu_ci(est_time=2, suite="base-a-test-cpu")
+
+
+def _assert_independent_copy(source: torch.Tensor, result: torch.Tensor) -> None:
+    assert torch.equal(result, source)
+    assert result is not source
+    assert result.is_contiguous()
+    assert result.storage_offset() == 0
+    assert result.untyped_storage().nbytes() == result.numel() * result.element_size()
+
+
+def test_skips_copy_for_exact_storage():
+    source = torch.arange(16).reshape(4, 4)
+    assert _copy_weight_view_before_h2d(source) is source
+
+
+def test_copies_zero_offset_storage_view():
+    backing = torch.arange(32).reshape(8, 4)
+    source = backing.narrow(0, 0, 2)
+    assert source.storage_offset() == 0
+    assert source.untyped_storage().nbytes() > source.numel() * source.element_size()
+    _assert_independent_copy(source, _copy_weight_view_before_h2d(source))
+
+
+def test_copies_nonzero_offset_storage_view():
+    backing = torch.arange(32).reshape(8, 4)
+    source = backing.narrow(0, 6, 2)
+    assert source.storage_offset() != 0
+    _assert_independent_copy(source, _copy_weight_view_before_h2d(source))
+
+
+def test_copies_noncontiguous_tensor():
+    source = torch.arange(16).reshape(4, 4).transpose(0, 1)
+    assert not source.is_contiguous()
+    _assert_independent_copy(source, _copy_weight_view_before_h2d(source))
+
+
+if __name__ == "__main__":
+    import sys
+
+    import pytest
+
+    sys.exit(pytest.main([__file__, "-v"]))