Fix create view usm offset - #3037
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_create_view() (introduced in IntelPython#2815) rebuilds the view with dpt.usm_ndarray(shape, dtype, buffer=self._array_obj, strides=...), and the constructor rebases such a view onto the whole underlying USM allocation with a default offset of 0. Any source array that does not start at the base of its allocation (e.g. a slice) therefore got a view onto the wrong memory, silently returning values from the base of the parent buffer. This is the same class of bug as the ones fixed in IntelPython#2651 (ndarray constructor with buffer=) and IntelPython#2812 (.data.ptr on views), but for the _create_view() helper added later for ndarray subclassing support. The impact is not limited to explicit .view() calls: dpnp.einsum() takes a "returns_view" fast path for a single operand with no summed index (any pure permutation, including the identity 'abc->abc') and calls .view() on each operand, so einsum over a sliced operand silently returned wrong values. The fix forwards the source array's element offset (converted to units of the view's dtype) to the usm_ndarray constructor, and raises a clear ValueError in the one case a usm_ndarray cannot represent: a byte offset that is not a multiple of the new itemsize. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Parametrize over all supported dtypes and several slice patterns (positive/negative steps, empty result), and add cases for 0-d views, chained views with accumulated offsets, memory sharing / write-through, complex<->real reinterpretation with an offset, and a second misaligned-offset error case. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
abagusetty
requested review from
antonwolfy,
ndgrigorian and
vlad-perevezentsev
as code owners
August 21, 2026 17:14
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Can one of the admins verify this patch? |
Widen the dtype sweep to 1- and 2-byte integer types and float16, which exercise the byte-offset / itemsize arithmetic far more than the default dtype list (4, 8 and 16-byte types only). Add cases for 3-D slices, F-ordered arrays, non-contiguous sources (transposed and column slices, including the numpy-compatible refusal to change the itemsize when the last axis is not contiguous), usm_type and sycl_queue preservation, write-through via a dtype-changing view, arithmetic and reduction kernels reading through an offset view, and an array built with both a `buffer=` offset and a constructor `offset=`. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
…setty/dpnp into fix-create-view-usm-offset
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Fixes #3036