svn commit: r334928 - head/lib/libc/stdlib
Konstantin Belousov
kib at FreeBSD.org
Sun Jun 10 17:54:45 UTC 2018
Author: kib
Date: Sun Jun 10 17:54:44 2018
New Revision: 334928
URL: https://svnweb.freebsd.org/changeset/base/334928
Log:
libc qsort(3): stop aliasing.
Qsort swap code aliases the sorted array elements to ints and longs in
order to do swap by machine words. Unfortunately this breaks with the
full code optimization, e.g. LTO.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201 which seems to
reference code directly copied from libc/stdlib/qsort.c.
PR: 228780
Reported by: mliska at suse.cz
Reviewed by: brooks
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D15714
Modified:
head/lib/libc/stdlib/qsort.c
Modified: head/lib/libc/stdlib/qsort.c
==============================================================================
--- head/lib/libc/stdlib/qsort.c Sun Jun 10 16:44:18 2018 (r334927)
+++ head/lib/libc/stdlib/qsort.c Sun Jun 10 17:54:44 2018 (r334928)
@@ -43,53 +43,27 @@ typedef int cmp_t(void *, const void *, const void *
typedef int cmp_t(const void *, const void *);
#endif
static inline char *med3(char *, char *, char *, cmp_t *, void *);
-static inline void swapfunc(char *, char *, size_t, int, int);
#define MIN(a, b) ((a) < (b) ? a : b)
/*
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
*/
-#define swapcode(TYPE, parmi, parmj, n) { \
- size_t i = (n) / sizeof (TYPE); \
- TYPE *pi = (TYPE *) (parmi); \
- TYPE *pj = (TYPE *) (parmj); \
- do { \
- TYPE t = *pi; \
- *pi++ = *pj; \
- *pj++ = t; \
- } while (--i > 0); \
-}
-#define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \
- ((char *)a - (char *)0) % sizeof(TYPE) || \
- es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1;
-
static inline void
-swapfunc(char *a, char *b, size_t n, int swaptype_long, int swaptype_int)
+swapfunc(char *a, char *b, size_t es)
{
- if (swaptype_long <= 1)
- swapcode(long, a, b, n)
- else if (swaptype_int <= 1)
- swapcode(int, a, b, n)
- else
- swapcode(char, a, b, n)
+ char t;
+
+ do {
+ t = *a;
+ *a++ = *b;
+ *b++ = t;
+ } while (--es > 0);
}
-#define swap(a, b) \
- if (swaptype_long == 0) { \
- long t = *(long *)(a); \
- *(long *)(a) = *(long *)(b); \
- *(long *)(b) = t; \
- } else if (swaptype_int == 0) { \
- int t = *(int *)(a); \
- *(int *)(a) = *(int *)(b); \
- *(int *)(b) = t; \
- } else \
- swapfunc(a, b, es, swaptype_long, swaptype_int)
-
#define vecswap(a, b, n) \
- if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int)
+ if ((n) > 0) swapfunc(a, b, n)
#ifdef I_AM_QSORT_R
#define CMP(t, x, y) (cmp((t), (x), (y)))
@@ -121,17 +95,16 @@ qsort(void *a, size_t n, size_t es, cmp_t *cmp)
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
size_t d1, d2;
int cmp_result;
- int swaptype_long, swaptype_int, swap_cnt;
+ int swap_cnt;
-loop: SWAPINIT(long, a, es);
- SWAPINIT(int, a, es);
+loop:
swap_cnt = 0;
if (n < 7) {
for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
for (pl = pm;
pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
pl -= es)
- swap(pl, pl - es);
+ swapfunc(pl, pl - es, es);
return;
}
pm = (char *)a + (n / 2) * es;
@@ -147,7 +120,7 @@ loop: SWAPINIT(long, a, es);
}
pm = med3(pl, pm, pn, cmp, thunk);
}
- swap(a, pm);
+ swapfunc(a, pm, es);
pa = pb = (char *)a + es;
pc = pd = (char *)a + (n - 1) * es;
@@ -155,7 +128,7 @@ loop: SWAPINIT(long, a, es);
while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
if (cmp_result == 0) {
swap_cnt = 1;
- swap(pa, pb);
+ swapfunc(pa, pb, es);
pa += es;
}
pb += es;
@@ -163,14 +136,14 @@ loop: SWAPINIT(long, a, es);
while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
if (cmp_result == 0) {
swap_cnt = 1;
- swap(pc, pd);
+ swapfunc(pc, pd, es);
pd -= es;
}
pc -= es;
}
if (pb > pc)
break;
- swap(pb, pc);
+ swapfunc(pb, pc, es);
swap_cnt = 1;
pb += es;
pc -= es;
@@ -180,7 +153,7 @@ loop: SWAPINIT(long, a, es);
for (pl = pm;
pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
pl -= es)
- swap(pl, pl - es);
+ swapfunc(pl, pl - es, es);
return;
}
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