[CK TILE] Refactor sequence_reverse_inclusive_scan

[CongMa13]

Proposed changes

Refactor ck tile sequence_reverse_inclusive_scan from recursive to for-loop.

Tracking issue: #3575

This pull request introduces a new lightweight array type, trivial_array, and refactors the sequence utilities to use it for improved constexpr support and simplicity. The changes also include updates to the build system to add container-related tests.

Core Library Improvements:

• Added a new header trivial_array.hpp that defines the trivial_array type, a constexpr-friendly array with basic accessors and no custom constructors.
• Updated includes in core.hpp and sequence.hpp to import trivial_array. [1] [2]

Refactoring to Use trivial_array:

• Refactored sequence utilities in sequence.hpp to use trivial_array instead of the previously forward-declared array type, including in histogram and array generation logic. [1] [2]
• Rewrote the implementation of sequence_reverse_inclusive_scan to use trivial_array for intermediate storage, improving constexpr evaluation and clarity.

Build System and Testing:

• Added a new test subdirectory for container tests and a GoogleTest executable for unit_sequence.cpp to the CMake build configuration. [1] [2]

[tenpercent]

Thanks! Could you also measure the build metrics improvements, e.g. number of templates instantiated, or wall time improvement for some target?

[tenpercent]

re: implementation, would it help to have separate compile-time functions for sequence reversal (constexpr function with c-array initialized with variadic indices and then reverse using a for-loop logic) and scan (with a similar structure)?

[CongMa13]

Refactor the code and added a reverse function

[Copilot]

Pull request overview

This PR refactors the sequence_reverse_inclusive_scan implementation in the CK TILE library from a recursive template-based approach to an iterative for-loop implementation. The changes improve compilation efficiency by reducing template instantiation depth.

Changes:

• Refactored sequence_reverse_inclusive_scan from recursive to iterative implementation using trivial_array
• Added comprehensive unit tests for sequence operations
• Introduced trivial_array container for constexpr operations

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
include/ck_tile/core/container/sequence.hpp	Refactored sequence_reverse_inclusive_scan to use iterative approach with trivial_array, replaced array with trivial_array in utility functions
include/ck_tile/core/container/trivial_array.hpp	New file introducing trivial_array container for constexpr aggregate initialization
include/ck_tile/core.hpp	Added include for new trivial_array.hpp header
test/ck_tile/core/container/unit_sequence.cpp	New comprehensive test suite covering sequence operations including scan, transform, reduce, and utility functions
test/ck_tile/core/container/CMakeLists.txt	Build configuration for new sequence unit tests
test/ck_tile/core/CMakeLists.txt	Added container subdirectory to test build

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[Copilot]

The variable result is referenced but never defined. This condition will always fail. The add_gtest_executable macro likely needs to set a return value variable, or this check should reference a variable that the macro actually sets.

Suggested change

	if(result EQUAL 0)
	target_link_libraries(ck_tile_unit_sequence PRIVATE utility)
	endif()
	target_link_libraries(ck_tile_unit_sequence PRIVATE utility)