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qsort(3): enhance to handle 32-bit aligned data on 64-bit systems

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Implement a small enhancement to the original qsort implementation:
If the data is 32 bit aligned we can side-step the long type
version and use int instead.

The change brings a modest but significant improvement in
32 bit workloads.

Relnotes:	yes

PR:		135718
Taken from:	ache
This commit is contained in:
Pedro F. Giffuni 2015-03-05 17:00:39 +00:00
parent 2d678f1f4f
commit 9382fabf1f
1 changed files with 21 additions and 12 deletions
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33
lib/libc/stdlib/qsort.c
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@ -41,7 +41,7 @@ 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 *, int, int);
static inline void swapfunc(char *, char *, int, int, int);
#define min(a, b) (a) < (b) ? a : b
@ -59,29 +59,37 @@ static inline void swapfunc(char *, char *, int, int);
} while (--i > 0); \
}
#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
#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(a, b, n, swaptype)
swapfunc(a, b, n, swaptype_long, swaptype_int)
char *a, *b;
int n, swaptype;
int n, swaptype_long, swaptype_int;
{
if(swaptype <= 1)
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)
}
#define swap(a, b) \
if (swaptype == 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)
swapfunc(a, b, es, swaptype_long, swaptype_int)
#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
#define vecswap(a, b, n) \
if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int)
#ifdef I_AM_QSORT_R
#define CMP(t, x, y) (cmp((t), (x), (y)))
@ -113,9 +121,10 @@ qsort(void *a, size_t n, size_t es, cmp_t *cmp)
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
size_t d, r;
int cmp_result;
int swaptype, swap_cnt;
int swaptype_long, swaptype_int, swap_cnt;
loop: SWAPINIT(a, es);
loop: SWAPINIT(long, a, es);
SWAPINIT(int, a, es);
swap_cnt = 0;
if (n < 7) {
for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)