Revert removal of multi-match discard heuristic in 27af01
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>
René Scharfe committed
Sep 25, 2011 at 21:39 UTC
c5aa90682f82fe0dabdc0280be93568d52efddfc
1 file changed
+7
-3
xdiff/xprepare.c
+7
-3
@@ -398,7 +398,7 @@ static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
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* might be potentially discarded if they happear in a run of discardable.
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*/
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static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
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- long i, nm, nreff;
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+ long i, nm, nreff, mlim;
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xrecord_t **recs;
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xdlclass_t *rcrec;
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char *dis, *dis1, *dis2;
@@ -411,16 +411,20 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
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dis1 = dis;
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dis2 = dis1 + xdf1->nrec + 1;
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+ if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
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+ mlim = XDL_MAX_EQLIMIT;
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for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
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rcrec = cf->rcrecs[(*recs)->ha];
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nm = rcrec ? rcrec->len2 : 0;
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- dis1[i] = (nm == 0) ? 0: 1;
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+ dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
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}
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+ if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
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+ mlim = XDL_MAX_EQLIMIT;
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for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
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rcrec = cf->rcrecs[(*recs)->ha];
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nm = rcrec ? rcrec->len1 : 0;
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- dis2[i] = (nm == 0) ? 0: 1;
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+ dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
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}
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for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];