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b80741e5b9
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 <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
57 lines
986 B
C
57 lines
986 B
C
#include "git-compat-util.h"
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/*
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* A merge sort implementation, simplified from the qsort implementation
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* by Mike Haertel, which is a part of the GNU C Library.
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*/
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static void msort_with_tmp(void *b, size_t n, size_t s,
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int (*cmp)(const void *, const void *),
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char *t)
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{
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char *tmp;
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char *b1, *b2;
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size_t n1, n2;
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if (n <= 1)
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return;
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n1 = n / 2;
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n2 = n - n1;
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b1 = b;
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b2 = (char *)b + (n1 * s);
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msort_with_tmp(b1, n1, s, cmp, t);
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msort_with_tmp(b2, n2, s, cmp, t);
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tmp = t;
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while (n1 > 0 && n2 > 0) {
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if (cmp(b1, b2) <= 0) {
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memcpy(tmp, b1, s);
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tmp += s;
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b1 += s;
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--n1;
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} else {
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memcpy(tmp, b2, s);
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tmp += s;
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b2 += s;
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--n2;
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}
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}
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if (n1 > 0)
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memcpy(tmp, b1, n1 * s);
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memcpy(b, t, (n - n2) * s);
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}
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void git_stable_qsort(void *b, size_t n, size_t s,
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int (*cmp)(const void *, const void *))
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{
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const size_t size = st_mult(n, s);
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char *tmp;
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tmp = xmalloc(size);
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msort_with_tmp(b, n, s, cmp, tmp);
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free(tmp);
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}
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