[Clang-tidy] Fix warning for uninitialized vars in fallbackReduction.hpp

[Akos299]

note: Calling 'FallbackReduction::sum'
672 | T sum = shamalgs::reduction::details::FallbackReduction::sum(
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
673 | shamsys::instance::get_compute_queue(), buf, 0, sz);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/__w/Shamrock/Shamrock/src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:95:16: note: Calling '_int_sum'
95 | return _int_sum(q, buf1, start_id, end_id);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/__w/Shamrock/Shamrock/src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:36:9: note: 'accum' declared without an initial value
36 | T accum;
| ^~~~~~~
/__w/Shamrock/Shamrock/src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:41:38: note: Assuming 'idx' is >= 'end_id'
41 | for (u32 idx = start_id; idx < end_id; idx++) {
| ^~~~~~~~~~~~
/__w/Shamrock/Shamrock/src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:41:13: note: Loop condition is false. Execution continues on line 50
41 | for (u32 idx = start_id; idx < end_id; idx++) {
| ^
/__w/Shamrock/Shamrock/src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:50:9: note: Undefined or garbage value returned to caller
50 | return accum;

[gemini-code-assist]

Summary of Changes

Hello @Akos299, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves Clang-tidy warnings related to uninitialized variables within the FallbackReduction implementation. By explicitly initializing accumulator variables in the _int_sum, _int_min, and _int_max functions, the changes prevent potential undefined behavior and enhance the robustness of the reduction algorithms.

Highlights

• Clang-tidy Warning Fix: Addressed Clang-tidy warnings regarding uninitialized variables in FallbackReduction functions by providing explicit initial values for accumulator variables.
• Accumulator Initialization: Ensured accum variables in _int_sum, _int_min, and _int_max functions are correctly initialized to prevent undefined behavior.
• Header Dependencies: Included necessary headers (shambase/numeric_limits.hpp, <cassert>, <limits>) to support the new initialization logic for min/max operations.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a critical bug identified by clang-tidy where accumulator variables in reduction functions could be uninitialized, leading to undefined behavior for empty ranges. By initializing accum in _int_sum, _int_min, and _int_max to the appropriate identity value, the code is now safer and more correct. I've added one comment regarding unnecessary header includes that can be cleaned up. Additionally, it's worth noting that with these initializations in place, the if (idx == start_id) checks within the reduction loops are now redundant. Removing this conditional logic would simplify the code and improve performance by eliminating a branch inside the loop. This could be a good candidate for a follow-up refactoring.

[github-actions]

Workflow report

workflow report corresponding to commit 8fe2f06
Commiter email is timothee.davidcleris@proton.me
GitHub page artifact URL GitHub page artifact link (can expire)

Pre-commit check report

Pre-commit check: ✅

trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check for merge conflicts................................................Passed
check that executables have shebangs.....................................Passed
check that scripts with shebangs are executable..........................Passed
check for added large files..............................................Passed
check for case conflicts.................................................Passed
check for broken symlinks................................................Passed
check yaml...............................................................Passed
detect private key.......................................................Passed
No-tabs checker..........................................................Passed
Tabs remover.............................................................Passed
Validate GitHub Workflows................................................Passed
clang-format.............................................................Passed
black....................................................................Passed
ruff check...............................................................Passed
Check doxygen headers....................................................Passed
Check license headers....................................................Passed
Check #pragma once.......................................................Passed
Check SYCL #include......................................................Passed
No ssh in git submodules remote..........................................Passed

Test pipeline can run.

Clang-tidy diff report

No relevant changes found.
Well done!

You should now go back to your normal life and enjoy a hopefully sunny day while waiting for the review.

Doxygen diff with main

Removed warnings : 7
New warnings : 7
Warnings count : 7417 → 7417 (0.0%)

Detailed changes :

- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:25: warning: Compound shamalgs::reduction::details::FallbackReduction is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:27: warning: Compound shamalgs::reduction::details::FallbackReduction is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:27: warning: Member sum(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:29: warning: Member min(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:29: warning: Member sum(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:31: warning: Member max(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:31: warning: Member min(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:33: warning: Member max(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of struct shamalgs::reduction::details::FallbackReduction is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:35: warning: Member _int_sum(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:37: warning: Member _int_sum(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:54: warning: Member _int_min(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:56: warning: Member _int_min(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.
- src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:73: warning: Member _int_max(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.
+ src/shamalgs/include/shamalgs/details/reduction/fallbackReduction.hpp:75: warning: Member _int_max(sycl::queue &q, sycl::buffer< T > &buf1, u32 start_id, u32 end_id) (function) of namespace shamalgs::reduction::details is not documented.