stable-qsort: avoid using potentially unaligned access

2022-01-07T23:48:40Z

Like in the previous patch for compat/qsort_s.c, remove the optimization of using an on-stack buffer to avoid small allocations. This ensures maximum alignment for the array elements and simplifies the code a bit. The performance impact for the current callers is unlikely to be noticeable: * compat/mingw.c::make_environment_block() uses ALLOC_ARRAY and ALLOC_GROW several times already, so another allocation of up to 1KB should not matter much. * diffcore-rename.c::diffcore_rename_extended() is called once per diff or twice per merge, and those require allocations for each object and more already. * merge-ort.c::detect_and_process_renames() is called once per merge. It's responsible for the two per-merge diffcore_rename_extended() calls mentioned above as well, though. So this is possibly the most impacted caller. Per-object allocations are likely to dwarf the additional small allocations in git_stable_qsort(), though. Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

Move git_sort(), a stable sort, into into libgit.a

2019-10-02T05:44:51Z

The `qsort()` function is not guaranteed to be stable, i.e. it does not promise to maintain the order of items it is told to consider equal. In contrast, the `git_sort()` function we carry in `compat/qsort.c` _is_ stable, by virtue of implementing a merge sort algorithm. In preparation for using a stable sort in Git's rename detection, move the stable sort into `libgit.a` so that it is compiled in unconditionally, and rename it to `git_stable_qsort()`. Note: this also makes the hack obsolete that was introduced in fe21c6b285d (mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8), 2018-10-30), where we included `compat/qsort.c` directly in `compat/mingw.c` to use the stable sort. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano

git/stable-qsort.c, branch jch

stable-qsort: avoid using potentially unaligned access

Move git_sort(), a stable sort, into into libgit.a