Date: Tue, 9 Mar 2021 18:02:13 -0300 From: Érico Nogueira To: musl@...ts.openwall.com Cc: Érico Nogueira Subject: [PATCH v3] add qsort_r and make qsort a wrapper around it we make qsort a wrapper by providing a wrapper_cmp function that uses the extra argument as a function pointer. should be optimized to a tail call on most architectures, as long as it's built with -fomit-frame-pointer, so the performance impact should be minimal. to keep the git history clean, for now qsort_r is implemented in qsort.c and qsort is implemented in qsort_nr.c. qsort.c also received a few trivial cleanups, including replacing (*cmp)() calls with cmp(). qsort_nr.c contains only wrapper_cmp and qsort as a qsort_r wrapper itself. --- Following suggestions from IRC, as few changes as possible to the files, a final clean up commit after this one would involve some git mv's (I won't make a patch for it). Added weak_alias to force qsort to use libc's qsort_r. If this can't be accepted due to the overhead on some archs (ppc, mips, arm in some situations?), maybe we could revisit v2 of the patch? include/stdlib.h | 1 + src/include/stdlib.h | 1 + src/stdlib/qsort.c | 37 ++++++++++++++++++++----------------- src/stdlib/qsort_nr.c | 14 ++++++++++++++ 4 files changed, 36 insertions(+), 17 deletions(-) create mode 100644 src/stdlib/qsort_nr.c diff --git a/include/stdlib.h b/include/stdlib.h index b54a051f..0c0ced5f 100644 --- a/include/stdlib.h +++ b/include/stdlib.h @@ -158,6 +158,7 @@ struct __locale_struct; float strtof_l(const char *__restrict, char **__restrict, struct __locale_struct *); double strtod_l(const char *__restrict, char **__restrict, struct __locale_struct *); long double strtold_l(const char *__restrict, char **__restrict, struct __locale_struct *); +void qsort_r (void *, size_t, size_t, int (*)(const void *, const void *, void *), void *); #endif #if defined(_LARGEFILE64_SOURCE) || defined(_BSD_SOURCE) diff --git a/src/include/stdlib.h b/src/include/stdlib.h index e9da2015..812b04de 100644 --- a/src/include/stdlib.h +++ b/src/include/stdlib.h @@ -8,6 +8,7 @@ hidden void __env_rm_add(char *, char *); hidden int __mkostemps(char *, int, int); hidden int __ptsname_r(int, char *, size_t); hidden char *__randname(char *); +hidden void __qsort_r (void *, size_t, size_t, int (*)(const void *, const void *, void *), void *); hidden void *__libc_malloc(size_t); hidden void *__libc_malloc_impl(size_t); diff --git a/src/stdlib/qsort.c b/src/stdlib/qsort.c index da58fd31..20e40dda 100644 --- a/src/stdlib/qsort.c +++ b/src/stdlib/qsort.c @@ -24,6 +24,7 @@ /* Smoothsort, an adaptive variant of Heapsort. Memory usage: O(1). Run time: Worst case O(n log n), close to O(n) in the mostly-sorted case. */ +#define _BSD_SOURCE #include #include #include @@ -31,7 +32,7 @@ #include "atomic.h" #define ntz(x) a_ctz_l((x)) -typedef int (*cmpfun)(const void *, const void *); +typedef int (*cmpfun)(const void *, const void *, void *); static inline int pntz(size_t p[2]) { int r = ntz(p[0] - 1); @@ -88,7 +89,7 @@ static inline void shr(size_t p[2], int n) p[1] >>= n; } -static void sift(unsigned char *head, size_t width, cmpfun cmp, int pshift, size_t lp[]) +static void sift(unsigned char *head, size_t width, cmpfun cmp, void *arg, int pshift, size_t lp[]) { unsigned char *rt, *lf; unsigned char *ar[14 * sizeof(size_t) + 1]; @@ -99,10 +100,10 @@ static void sift(unsigned char *head, size_t width, cmpfun cmp, int pshift, size rt = head - width; lf = head - width - lp[pshift - 2]; - if((*cmp)(ar[0], lf) >= 0 && (*cmp)(ar[0], rt) >= 0) { + if(cmp(ar[0], lf, arg) >= 0 && cmp(ar[0], rt, arg) >= 0) { break; } - if((*cmp)(lf, rt) >= 0) { + if(cmp(lf, rt, arg) >= 0) { ar[i++] = lf; head = lf; pshift -= 1; @@ -115,7 +116,7 @@ static void sift(unsigned char *head, size_t width, cmpfun cmp, int pshift, size cycle(width, ar, i); } -static void trinkle(unsigned char *head, size_t width, cmpfun cmp, size_t pp[2], int pshift, int trusty, size_t lp[]) +static void trinkle(unsigned char *head, size_t width, cmpfun cmp, void *arg, size_t pp[2], int pshift, int trusty, size_t lp[]) { unsigned char *stepson, *rt, *lf; @@ -130,13 +131,13 @@ static void trinkle(unsigned char *head, size_t width, cmpfun cmp, size_t pp[2], ar[0] = head; while(p[0] != 1 || p[1] != 0) { stepson = head - lp[pshift]; - if((*cmp)(stepson, ar[0]) <= 0) { + if(cmp(stepson, ar[0], arg) <= 0) { break; } if(!trusty && pshift > 1) { rt = head - width; lf = head - width - lp[pshift - 2]; - if((*cmp)(rt, stepson) >= 0 || (*cmp)(lf, stepson) >= 0) { + if(cmp(rt, stepson, arg) >= 0 || cmp(lf, stepson, arg) >= 0) { break; } } @@ -150,11 +151,11 @@ static void trinkle(unsigned char *head, size_t width, cmpfun cmp, size_t pp[2], } if(!trusty) { cycle(width, ar, i); - sift(head, width, cmp, pshift, lp); + sift(head, width, cmp, arg, pshift, lp); } } -void qsort(void *base, size_t nel, size_t width, cmpfun cmp) +void __qsort_r(void *base, size_t nel, size_t width, cmpfun cmp, void *arg) { size_t lp[12*sizeof(size_t)]; size_t i, size = width * nel; @@ -173,16 +174,16 @@ void qsort(void *base, size_t nel, size_t width, cmpfun cmp) while(head < high) { if((p[0] & 3) == 3) { - sift(head, width, cmp, pshift, lp); + sift(head, width, cmp, arg, pshift, lp); shr(p, 2); pshift += 2; } else { if(lp[pshift - 1] >= high - head) { - trinkle(head, width, cmp, p, pshift, 0, lp); + trinkle(head, width, cmp, arg, p, pshift, 0, lp); } else { - sift(head, width, cmp, pshift, lp); + sift(head, width, cmp, arg, pshift, lp); } - + if(pshift == 1) { shl(p, 1); pshift = 0; @@ -191,12 +192,12 @@ void qsort(void *base, size_t nel, size_t width, cmpfun cmp) pshift = 1; } } - + p[0] |= 1; head += width; } - trinkle(head, width, cmp, p, pshift, 0, lp); + trinkle(head, width, cmp, arg, p, pshift, 0, lp); while(pshift != 1 || p[0] != 1 || p[1] != 0) { if(pshift <= 1) { @@ -208,11 +209,13 @@ void qsort(void *base, size_t nel, size_t width, cmpfun cmp) pshift -= 2; p[0] ^= 7; shr(p, 1); - trinkle(head - lp[pshift] - width, width, cmp, p, pshift + 1, 1, lp); + trinkle(head - lp[pshift] - width, width, cmp, arg, p, pshift + 1, 1, lp); shl(p, 1); p[0] |= 1; - trinkle(head - width, width, cmp, p, pshift, 1, lp); + trinkle(head - width, width, cmp, arg, p, pshift, 1, lp); } head -= width; } } + +weak_alias(__qsort_r, qsort_r); diff --git a/src/stdlib/qsort_nr.c b/src/stdlib/qsort_nr.c new file mode 100644 index 00000000..fe408fb1 --- /dev/null +++ b/src/stdlib/qsort_nr.c @@ -0,0 +1,14 @@ +#define _BSD_SOURCE +#include + +typedef int (*cmpfun)(const void *, const void *); + +static int wrapper_cmp(const void *v1, const void *v2, void *cmp) +{ + return ((cmpfun)cmp)(v1, v2); +} + +void qsort(void *base, size_t nel, size_t width, cmpfun cmp) +{ + __qsort_r(base, nel, width, wrapper_cmp, cmp); +} -- 2.30.2