dpm.as_usm_memory(X[i]) returns unexpected value

[densmirn]

Reproducer:

import dpctl
print(dpctl.__version__)
import dpctl.tensor as dpt
import dpctl.memory as dpm
X = dpt.usm_ndarray(10, dtype="|f8")
Y = np.arange(X.size, dtype=X.dtype)
X.usm_data.copy_from_host(Y.view("|u1"))
print("X =", dpm.as_usm_memory(X).copy_to_host().view(X.dtype))
print("X[0] =", dpm.as_usm_memory(X[0]).copy_to_host().view(X.dtype))
print("X[1] =", dpm.as_usm_memory(X[1]).copy_to_host().view(X.dtype))
print("X[2] =", dpm.as_usm_memory(X[2]).copy_to_host().view(X.dtype))

Output:

0.10.0dev0+44.gb60ce2a.dirty
X = [0. 1. 2. 3. 4. 5. 6. 7. 8. 9.]
X[0] = [0.]
X[1] = [2.]
X[2] = [4.]

[oleksandr-pavlyk]

Thanks for the report @densmirn

The sycl USM array interface produced by the slice gives the actual memory address, and also sets offset which specifies the location of this memory address from the start of the underlying allocation.

The dpm.as_memory interprets offset as saying start at this additional displacement relative to the provided pointer. The fix should not be complicated, but I need to trace through the code to understand what is the correct way to handle offset.