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Revert removal of multi-match discard heuristic in 27af01

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27af01d (xdiff/xprepare: improve O(n*m) performance in
xdl_cleanup_records(), 2011-08-17) was supposed to be a performance
boost only. However, it unexpectedly changed the behaviour of diff.

Revert a part of 27af01d that removes logic that mark lines as
"multi-match" (ie. dis[i] == 2). This was preventing the multi-match
discard heuristic (performed in xdl_cleanup_records() and
xdl_clean_mmatch()) from executing.

Reported-by: Alexander Pepper <pepper@inf.fu-berlin.de>
Signed-off-by: René Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
René Scharfe 2011-09-25 21:39:08 +08:00 committed by Junio C Hamano
parent 27af01d552
commit c5aa90682f
1 changed files with 7 additions and 3 deletions
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10
xdiff/xprepare.c
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@ -398,7 +398,7 @@ static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
* might be potentially discarded if they happear in a run of discardable. * might be potentially discarded if they happear in a run of discardable.
*/ */
static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) { static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
long i, nm, nreff; long i, nm, nreff, mlim;
xrecord_t **recs; xrecord_t **recs;
xdlclass_t *rcrec; xdlclass_t *rcrec;
char *dis, *dis1, *dis2; char *dis, *dis1, *dis2;
@ -411,16 +411,20 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
dis1 = dis; dis1 = dis;
dis2 = dis1 + xdf1->nrec + 1; dis2 = dis1 + xdf1->nrec + 1;
if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
mlim = XDL_MAX_EQLIMIT;
for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) { for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
rcrec = cf->rcrecs[(*recs)->ha]; rcrec = cf->rcrecs[(*recs)->ha];
nm = rcrec ? rcrec->len2 : 0; nm = rcrec ? rcrec->len2 : 0;
dis1[i] = (nm == 0) ? 0: 1; dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
} }
if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
mlim = XDL_MAX_EQLIMIT;
for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) { for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
rcrec = cf->rcrecs[(*recs)->ha]; rcrec = cf->rcrecs[(*recs)->ha];
nm = rcrec ? rcrec->len1 : 0; nm = rcrec ? rcrec->len1 : 0;
dis2[i] = (nm == 0) ? 0: 1; dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
} }
for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];