BUG: Fix INT_MIN % -1 to return 0 for all signed integer types (#29893)#29921
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charris merged 1 commit intonumpy:maintenance/2.3.xfrom Oct 10, 2025
Merged
BUG: Fix INT_MIN % -1 to return 0 for all signed integer types (#29893)#29921charris merged 1 commit intonumpy:maintenance/2.3.xfrom
charris merged 1 commit intonumpy:maintenance/2.3.xfrom
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…#29893) * BUG: Fix INT_MIN % -1 to return 0 for all signed integer types - Explicitly check for INT_MIN % -1 in scalar tail loops for fmod and remainder kernels. - Set result to 0 to avoid undefined behavior and match NumPy/Python expectations. - Ensures correct, portable behavior on all platforms (e.g., PPC64LE). * Apply suggestion from @seberg --------- Co-authored-by: Sebastian Berg <[email protected]>
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Backport of #29893.
Summary of changes
Explicitly handle the case INT_MIN % -1 in scalar tail loops for fmod and remainder kernels.
Set the result to 0 to avoid undefined behavior and align with NumPy/Python expected semantics.
Ensures portable, correct behavior across all architectures, including POWER10 (ppc64le).
Background / Motivation
On POWER10 systems, several SIMD tests were failing due to integer overflow when evaluating INT_MIN % -1, an undefined operation in C.
Python defines this operation to return 0, and this change updates NumPy’s low-level implementation to match that behavior.
Issue Reference
Fixes: #29731 — [POWER10] SIMD tests failing with integer overflow (previously skipped)
cc: @seiko2plus @rgommers @ghatwala