Upgrade faiss to 1.14.2

[aamijar]

Faiss has released v1.14.2 which includes an upgrade to cuVS 26.02. We can now remove the corresponding patches from cuvs and bump the faiss version that we are building against.

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between fc84a82 and 9487121.

📒 Files selected for processing (1)

• cpp/cmake/patches/faiss-1.14-cuvs-26.04.diff

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📝 Walkthrough

Summary by CodeRabbit

• Chores

  • Bumped FAISS GPU to 1.14.2; standardized on C++20.
  • Modernized cuVS integration and RMM pinned/managed/device memory usage, switching to synchronized allocation/deallocation patterns and updated pinned-host memory resource.

• Bug Fixes

  • Improved stability and correctness of GPU index operations, including centroid/rotation handling, neighbor list layouts, and query/update paths.
  • Adjusted includes and platform macros for more reliable compilation across toolchains.

Walkthrough

This PR modernizes FAISS cuVS integration: migrate to cuvs::distance::DistanceType, update RMM pinned/managed/device memory APIs and includes, refactor IVFPQ center/rotation writeback and inverted-list handling, enforce C++20, and pin FAISS to 1.14.2.

Changes

FAISS cuVS Modernization Patches

Layer / File(s)	Summary
Distance type and header updates cpp/cmake/patches/faiss-1.14-cuvs-25.12.diff, cpp/cmake/patches/faiss-1.14-cuvs-26.04.diff	Switch cuVS include to distance.hpp; metricFaissToCuvs returns cuvs::distance::DistanceType. Query sites use auto for the cuVS distance variable; add missing Thrust include.
RMM memory-resource & allocation API modernization cpp/cmake/patches/faiss-1.14-cuvs-25.12.diff	Update RMM header paths and change StandardGpuResourcesImpl::pmr_ to rmm::mr::pinned_host_memory_resource. Replace async allocation/deallocation calls with the updated sync/positional RMM APIs for pinned, device/unified, and managed paths.
CMake C++ standard cpp/cmake/patches/faiss-1.14-cuvs-26.02.diff	Unconditionally set CMAKE_CXX_STANDARD to 20.
IVFPQ center & rotation writeback cpp/cmake/patches/faiss-1.14-cuvs-26.02.diff	CuvsIVFPQ::updateQuantizer writes PQ centers and rotation matrices via mutable device-matrix views, pads centers with norms, then applies rotate_padded_centers instead of helpers::set_centers.
IVFPQ inverted-list spec and helpers cpp/cmake/patches/faiss-1.14-cuvs-26.02.diff	copyInvertedListsFrom uses ivf_pq::list_spec_interleaved and cuvs::neighbors::ivf_pq::helpers::resize_list; setPQCentroids_ adds a const_cast<float*> for raft::copy.
FAISS version override cpp/cmake/patches/faiss_override.json	Pin faiss package version to 1.14.2 so the patches target the updated release baseline.

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

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Possibly related PRs

• rapidsai/cuvs#1796: Both PRs modify the build CMake configuration to enforce C++20 (unconditionally setting CMAKE_CXX_STANDARD=20).

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Suggested reviewers

• cjnolet

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Upgrade faiss to 1.14.2' clearly and specifically summarizes the main change in the changeset.
Description check	✅ Passed	The description directly relates to the changeset by explaining the rationale for upgrading faiss to 1.14.2 and removing associated patches.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[cjnolet]

Why are we maintaining so many diffs? Can't we just use the most recent version?

[tarang-jain]

yes that is what I was thinking as well. @aamijar lets just maintain a single patch per release. The pinned faiss version is always fixed and the patch should be only tied to that and the current cuvs build.

[tarang-jain]

we'd probably want to rename the suffix to -cuvs-26.08.diff here for the current release.