* Modifications from vanilla NetBSD source:
* Add do ... while() macro fix
* Remove __inline, _DIAGASSERTs, __P
+ * Remove ill-considered "swap_cnt" switch to insertion sort,
+ * in favor of a simple check for presorted input.
*
- * $PostgreSQL: pgsql/src/port/qsort.c,v 1.8 2005/10/15 02:49:51 momjian Exp $
+ * $PostgreSQL: pgsql/src/port/qsort.c,v 1.9 2006/03/21 19:49:15 tgl Exp $
*/
/* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $ */
#define min(a, b) ((a) < (b) ? (a) : (b))
/*
- * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
+ * Qsort routine based on J. L. Bentley and M. D. McIlroy,
+ * "Engineering a sort function",
+ * Software--Practice and Experience 23 (1993) 1249-1265.
+ * We have modified their original by adding a check for already-sorted input,
+ * which seems to be a win per discussions on pgsql-hackers around 2006-03-21.
*/
#define swapcode(TYPE, parmi, parmj, n) \
do { \
int d,
r,
swaptype,
- swap_cnt;
+ presorted;
loop:SWAPINIT(a, es);
- swap_cnt = 0;
if (n < 7)
{
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
swap(pl, pl - es);
return;
}
+ presorted = 1;
+ for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
+ {
+ if (cmp(pm - es, pm) > 0)
+ {
+ presorted = 0;
+ break;
+ }
+ }
+ if (presorted)
+ return;
pm = (char *) a + (n / 2) * es;
if (n > 7)
{
}
swap(a, pm);
pa = pb = (char *) a + es;
-
pc = pd = (char *) a + (n - 1) * es;
for (;;)
{
{
if (r == 0)
{
- swap_cnt = 1;
swap(pa, pb);
pa += es;
}
{
if (r == 0)
{
- swap_cnt = 1;
swap(pc, pd);
pd -= es;
}
if (pb > pc)
break;
swap(pb, pc);
- swap_cnt = 1;
pb += es;
pc -= es;
}
- if (swap_cnt == 0)
- { /* Switch to insertion sort */
- for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
- for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
- pl -= es)
- swap(pl, pl - es);
- return;
- }
-
pn = (char *) a + n * es;
r = min(pa - (char *) a, pb - pa);
vecswap(a, pb - r, r);