mirror of https://github.com/postgres/postgres
Per recent work by Peter Geoghegan, it's significantly faster to tuplesort on a single sortkey if ApplySortComparator is inlined into quicksort rather reached via a function pointer. It's also faster in general to have a version of quicksort which is specialized for sorting SortTuple objects rather than objects of arbitrary size and type. This requires a couple of additional copies of the quicksort logic, which in this patch are generate using a Perl script. There might be some benefit in adding further specializations here too, but thus far it's not clear that those gains are worth their weight in code footprint.pull/1/head
Robert Haas
14 years ago
parent
ac9100f8cf
commit
337b6f5ecf
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/qsort_tuple.c |
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#!/usr/bin/perl -w |
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|
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# |
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# gen_qsort_tuple.pl |
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# |
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# This script generates specialized versions of the quicksort algorithm for |
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# tuple sorting. The quicksort code is derived from the NetBSD code. The |
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# code generated by this script runs significantly faster than vanilla qsort |
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# when used to sort tuples. This speedup comes from a number of places. |
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# The major effects are (1) inlining simple tuple comparators is much faster |
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# than jumping through a function pointer and (2) swap and vecswap operations |
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# specialized to the particular data type of interest (in this case, SortTuple) |
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# are faster than the generic routines. |
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# |
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# Modifications from vanilla NetBSD source: |
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# Add do ... while() macro fix |
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# Remove __inline, _DIAGASSERTs, __P |
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# Remove ill-considered "swap_cnt" switch to insertion sort, |
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# in favor of a simple check for presorted input. |
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# Instead of sorting arbitrary objects, we're always sorting SortTuples |
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# Add CHECK_FOR_INTERRUPTS() |
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# |
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# CAUTION: if you change this file, see also qsort.c and qsort_arg.c |
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# |
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use strict; |
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my $SUFFIX; |
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my $EXTRAARGS; |
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my $EXTRAPARAMS; |
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my $CMPPARAMS; |
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emit_qsort_boilerplate(); |
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$SUFFIX = 'tuple'; |
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$EXTRAARGS = ', SortTupleComparator cmp_tuple, Tuplesortstate *state'; |
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$EXTRAPARAMS = ', cmp_tuple, state'; |
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$CMPPARAMS = ', state'; |
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emit_qsort_implementation(); |
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|
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$SUFFIX = 'ssup'; |
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$EXTRAARGS = ', SortSupport ssup'; |
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$EXTRAPARAMS = ', ssup'; |
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$CMPPARAMS = ', ssup'; |
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print <<'EOM'; |
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#define cmp_ssup(a, b, ssup) \ |
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ApplySortComparator((a)->datum1, (a)->isnull1, \ |
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(b)->datum1, (b)->isnull1, ssup) |
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EOM |
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emit_qsort_implementation(); |
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|
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sub emit_qsort_boilerplate |
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{ |
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print <<'EOM'; |
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/* |
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* autogenerated by src/backend/utils/sort/gen_qsort_tuple.pl, do not edit |
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* This file is included by tuplesort.c, rather than compiled separately. |
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*/ |
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|
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/* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $ */ |
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|
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/*- |
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* Copyright (c) 1992, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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|
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/* |
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* Qsort routine based on J. L. Bentley and M. D. McIlroy, |
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* "Engineering a sort function", |
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* Software--Practice and Experience 23 (1993) 1249-1265. |
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* We have modified their original by adding a check for already-sorted input, |
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* which seems to be a win per discussions on pgsql-hackers around 2006-03-21. |
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*/ |
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static void |
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swapfunc(SortTuple *a, SortTuple *b, size_t n) |
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{ |
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do |
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{ |
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SortTuple t = *a; |
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*a++ = *b; |
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*b++ = t; |
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} while (--n > 0); |
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} |
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|
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#define swap(a, b) \ |
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do { \ |
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SortTuple t = *(a); \ |
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*(a) = *(b); \ |
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*(b) = t; \ |
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} while (0); |
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#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n)) |
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EOM |
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} |
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sub emit_qsort_implementation |
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{ |
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print <<EOM; |
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static SortTuple * |
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med3_$SUFFIX(SortTuple *a, SortTuple *b, SortTuple *c$EXTRAARGS) |
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{ |
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return cmp_$SUFFIX(a, b$CMPPARAMS) < 0 ? |
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(cmp_$SUFFIX(b, c$CMPPARAMS) < 0 ? b : |
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(cmp_$SUFFIX(a, c$CMPPARAMS) < 0 ? c : a)) |
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: (cmp_$SUFFIX(b, c$CMPPARAMS) > 0 ? b : |
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(cmp_$SUFFIX(a, c$CMPPARAMS) < 0 ? a : c)); |
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} |
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|
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static void |
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qsort_$SUFFIX(SortTuple *a, size_t n$EXTRAARGS) |
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{ |
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SortTuple *pa, |
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*pb, |
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*pc, |
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*pd, |
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*pl, |
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*pm, |
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*pn; |
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int d, |
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r, |
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presorted; |
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loop: |
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CHECK_FOR_INTERRUPTS(); |
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if (n < 7) |
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{ |
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for (pm = a + 1; pm < a + n; pm++) |
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for (pl = pm; pl > a && cmp_$SUFFIX(pl - 1, pl$CMPPARAMS) > 0; pl--) |
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swap(pl, pl - 1); |
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return; |
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} |
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presorted = 1; |
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for (pm = a + 1; pm < a + n; pm++) |
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{ |
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CHECK_FOR_INTERRUPTS(); |
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if (cmp_$SUFFIX(pm - 1, pm$CMPPARAMS) > 0) |
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{ |
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presorted = 0; |
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break; |
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} |
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} |
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if (presorted) |
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return; |
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pm = a + (n / 2); |
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if (n > 7) |
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{ |
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pl = a; |
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pn = a + (n - 1); |
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if (n > 40) |
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{ |
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d = (n / 8); |
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pl = med3_$SUFFIX(pl, pl + d, pl + 2 * d$EXTRAPARAMS); |
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pm = med3_$SUFFIX(pm - d, pm, pm + d$EXTRAPARAMS); |
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pn = med3_$SUFFIX(pn - 2 * d, pn - d, pn$EXTRAPARAMS); |
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} |
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pm = med3_$SUFFIX(pl, pm, pn$EXTRAPARAMS); |
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} |
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swap(a, pm); |
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pa = pb = a + 1; |
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pc = pd = a + (n - 1); |
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for (;;) |
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{ |
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while (pb <= pc && (r = cmp_$SUFFIX(pb, a$CMPPARAMS)) <= 0) |
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{ |
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CHECK_FOR_INTERRUPTS(); |
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if (r == 0) |
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{ |
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swap(pa, pb); |
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pa++; |
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} |
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pb++; |
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} |
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while (pb <= pc && (r = cmp_$SUFFIX(pc, a$CMPPARAMS)) >= 0) |
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{ |
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CHECK_FOR_INTERRUPTS(); |
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if (r == 0) |
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{ |
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swap(pc, pd); |
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pd--; |
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} |
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pc--; |
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} |
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if (pb > pc) |
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break; |
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swap(pb, pc); |
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pb++; |
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pc--; |
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} |
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pn = a + n; |
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r = Min(pa - a, pb - pa); |
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vecswap(a, pb - r, r); |
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r = Min(pd - pc, pn - pd - 1); |
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vecswap(pb, pn - r, r); |
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if ((r = pb - pa) > 1) |
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qsort_$SUFFIX(a, r$EXTRAPARAMS); |
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if ((r = pd - pc) > 1) |
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{ |
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/* Iterate rather than recurse to save stack space */ |
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a = pn - r; |
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n = r; |
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goto loop; |
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} |
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/* qsort_$SUFFIX(pn - r, r$EXTRAPARAMS);*/ |
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} |
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EOM |
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} |
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