Implement Portable bucketize

[Gallinator]

Fixes #20270

Summary

Add portable scalar and tensor bucketize operator, based on the PyTorch implementation.
Key differences from the PyTorch implementation:

• Implemented only bucketize, no searchsorted
• Boundaries tensor size is not checked against output type, as SizesType is an int32_t and must be 1D
• In the original implementation the input scalar is wrapped into a tensor, here two sets of functions are used instead
• Supports both NHWC and NCHW as it is a pointwise kernel and there is no sorter argument. This avoids creating contiguous tensors

Release notes: ops & kernels

Test plan

C++ tests are extensive and include failure and edge cases tests.
Python tests compare the output of an exported module to the PyTorch implementation only for normal and edge cases, similar to #15893.

cc @larryliu0820 @manuelcandales

[pytorch-bot]

🔗 Helpful Links

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[Gallinator]

@pytorchbot label "release notes: ops & kernels"

[Gasoonjia]

@claude review this PR

[claude]

Claude finished @Gasoonjia's task in 5m 32s —— View job

---

PR Review: Implement Portable bucketize

• Read changed files (op_bucketize.cpp, tests, functions.yaml, build files)
• Analyze correctness, conventions, and tests

Nice work — the kernel is clean, the C++ test coverage is genuinely thorough (edge cases, inf, empty, dtype matrix, failure paths), and the choice to support both NHWC/NCHW via the matching-dim-order check is correct: since self and out are required to have the same shape and the same dim order, iterating linear physical indices i for both loads and stores maps to the same logical element, so no contiguous copy is needed. Below are the issues I found.

Bugs

1. test_bucketize_scalar_out_int32 doesn't test int32 — kernels/test/test_bucketize.py:126-131
The "int32" test constructs BucketizeModule(out_int32=False, ...), so it's an exact duplicate of the int64 test and never exercises the int32 path. Set out_int32=True.

def test_bucketize_scalar_out_int32(self):
    model = BucketizeModule(out_int32=False, right=False)  # should be True

Fix this →

Conventions

2. Missing BSD license header — op_bucketize.cpp, op_bucketize_test.cpp, test_bucketize.py
All three new files start directly with includes/code. Every other file under kernels/portable/cpu/ and kernels/test/ carries the standard Copyright (c) Meta Platforms, Inc. and affiliates. ... BSD-style license header. Please add it.

3. bucketize_tensor_out requires a pre-sized out instead of resizing it — op_bucketize.cpp:177-180
The kernel checks tensors_have_same_shape(self, out) but never calls resize_tensor(out, self.sizes()). Most portable out-variant kernels (e.g. op_clamp.cpp:129) resize out to the input size so they work with dynamic / upper-bound shapes where the planner allocates out at a max size. With a hard same-shape check this op will fail under dynamic shapes. Consider:

ET_KERNEL_CHECK(
    context, resize_tensor(out, self.sizes()) == Error::Ok, InvalidArgument, out);

(For the scalar variant, the out.dim() == 0 check is fine as-is.)

Minor / style

• op_bucketize.cpp:69,108 — const bool& right passes a bool by const reference; pass by value (bool right).
• op_bucketize.cpp:80,116 — boundaries.sizes().back() can be boundaries.numel() since boundaries is already validated as 1D; slightly clearer.
• test_bucketize.py — every test docstring says "Test bucketize.Tensor_out", including the scalar tests (lines 120, 126, etc.). Worth correcting the scalar ones.

Things I checked that look correct

• Compute-type promotion (promote_type_with_scalar for scalar, promoteTypes for tensor) and the REALHBF16 dtype switch.
• out_int32 ↔ output dtype validation, complex-type and N-D-boundaries rejection paths.
• Binary-search cus_lower_bound/cus_upper_bound for right/left semantics, empty boundaries (returns 0), and out-of-range / inf inputs — all covered by tests.
• Build registration in functions.yaml, targets.bzl, and CMakeLists.txt.

Overall this is close to merge-ready; only item #1 is a real functional gap, and #2 is required for CI conventions.
· branch bucketize

[Gasoonjia]

Thanks for contribution! I have a question left in the issue mind check that?

[Gasoonjia]

plz do not put export test script under kernels/test. Only the runtime test should be fine.

[Gallinator]

@Gasoonjia So I have to remove test_bucketize.py ? I see that in #15893 they added an export test as well