Deprecate AgentMergeSortPolicy and AgentAdjacentDifferencePolicy

[bernhardmgruber]

Left over from #9218 and #8600.

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Reviewing files that changed from the base of the PR and between d2286ed and 24aaaa2.

📒 Files selected for processing (2)

• cub/cub/agent/agent_adjacent_difference.cuh
• cub/cub/device/dispatch/tuning/tuning_merge_sort.cuh

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Overview

This pull request deprecates AgentMergeSortPolicy and AgentAdjacentDifferencePolicy by moving their implementations into internal detail:: agent policy structs and exposing the original names as deprecated aliases. The change completes cleanup left over from PRs #9218 and #8600 and preserves behavior while steering users toward the tuning API.

Changes

Adjacent Difference Policy

• cub/cub/agent/agent_adjacent_difference.cuh

  • Added internal detail::agent_adjacent_difference_policy template (encapsulates block/tiling and load/store algorithm constants).
  • Replaced the former struct definition of AgentAdjacentDifferencePolicy with a deprecated using alias to detail::agent_adjacent_difference_policy (keeps CCCL_DEPRECATED_BECAUSE("Use the tuning API for DeviceAdjacentDifference")).

• cub/cub/device/dispatch/dispatch_adjacent_difference.cuh

  • Device kernel now instantiates the internal agent_adjacent_difference_policy instead of AgentAdjacentDifferencePolicy. No control flow or kernel logic changes.

• cub/cub/device/dispatch/tuning/tuning_adjacent_difference.cuh

  • Tuning policy_hub::Policy500 now references detail::agent_adjacent_difference_policy (same template arguments preserved).

Merge Sort Policy

• cub/cub/device/dispatch/tuning/tuning_merge_sort.cuh
  • Introduced detail::agent_merge_sort_policy template and replaced direct implementation use with it.
  • Exposed AgentMergeSortPolicy as a deprecated using alias to detail::agent_merge_sort_policy with CCCL_DEPRECATED_BECAUSE("Use the tuning API for DeviceMergeSort").
  • Updated tuning policy hub specializations (Policy500, Policy520/Policy600) to instantiate the internal agent_merge_sort_policy while preserving existing template arguments and NVHPC conditional behavior.

API / ABI impact

• Public names AgentAdjacentDifferencePolicy and AgentMergeSortPolicy remain available but now are deprecated aliases to internal detail:: types; no signature changes to exported functions or kernels.
• Deprecation attributes are preserved on the public aliases to guide users to the tuning API.

Review notes

• Changes are refactor-only for policy indirection; behavioral and functional code paths are unchanged.
• Suggested reviewers should pay attention to the deprecated alias attributes and any references elsewhere in the codebase to ensure consistency when fully removing these aliases in the future.

suggestion:

Walkthrough

Refactors adjacent-difference and merge-sort agent policies by introducing internal detail::agent_*_policy structs and replacing the former public policy structs with deprecated using aliases; dispatch and tuning code now instantiate the internal policy types directly.

Changes

Policy Type Abstraction Refactoring

Layer / File(s)	Summary
Adjacent-difference policy abstraction cub/cub/agent/agent_adjacent_difference.cuh, cub/cub/device/dispatch/dispatch_adjacent_difference.cuh, cub/cub/device/dispatch/tuning/tuning_adjacent_difference.cuh	Defines detail::agent_adjacent_difference_policy, replaces public AgentAdjacentDifferencePolicy with a deprecated alias, and updates dispatch and tuning aliases to instantiate the internal policy type.
Merge-sort policy abstraction cub/cub/device/dispatch/tuning/tuning_merge_sort.cuh	Adds detail::agent_merge_sort_policy, exposes AgentMergeSortPolicy as a deprecated alias to the internal type, and updates Policy500/Policy520/Policy600 tuning aliases to instantiate the internal policy type.

Possibly related PRs

• NVIDIA/cccl#9218: Related adjacent-difference dispatch/tuning policy changes that interact with the refactored AgentAdjacentDifferencePolicy type.

Suggested reviewers

• shwina
• srinivasyadav18
• NaderAlAwar

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