D2686: xdiff: add a preprocessing step that trims files
quark (Jun Wu)
phabricator at mercurial-scm.org
Fri Mar 9 22:54:27 UTC 2018
quark updated this revision to Diff 6797.
REPOSITORY
rHG Mercurial
CHANGES SINCE LAST UPDATE
https://phab.mercurial-scm.org/D2686?vs=6708&id=6797
REVISION DETAIL
https://phab.mercurial-scm.org/D2686
AFFECTED FILES
mercurial/thirdparty/xdiff/xdiffi.c
mercurial/thirdparty/xdiff/xprepare.c
mercurial/thirdparty/xdiff/xtypes.h
CHANGE DETAILS
diff --git a/mercurial/thirdparty/xdiff/xtypes.h b/mercurial/thirdparty/xdiff/xtypes.h
--- a/mercurial/thirdparty/xdiff/xtypes.h
+++ b/mercurial/thirdparty/xdiff/xtypes.h
@@ -60,6 +60,10 @@
typedef struct s_xdfenv {
xdfile_t xdf1, xdf2;
+
+ /* number of lines for common prefix and suffix that are removed
+ * from xdf1 and xdf2 as a preprocessing step */
+ long nprefix, nsuffix;
} xdfenv_t;
diff --git a/mercurial/thirdparty/xdiff/xprepare.c b/mercurial/thirdparty/xdiff/xprepare.c
--- a/mercurial/thirdparty/xdiff/xprepare.c
+++ b/mercurial/thirdparty/xdiff/xprepare.c
@@ -156,6 +156,87 @@
}
+/*
+ * Trim common prefix from files.
+ *
+ * Note: trimming could affect hunk shifting. But the performance benefit
+ * outweighs the shift change. A diff result with suboptimal shifting is still
+ * valid.
+ */
+static void xdl_trim_files(mmfile_t *mf1, mmfile_t *mf2, long reserved,
+ xdfenv_t *xe, mmfile_t *out_mf1, mmfile_t *out_mf2) {
+ mmfile_t msmall, mlarge;
+ /* prefix lines, prefix bytes, suffix lines, suffix bytes */
+ long plines = 0, pbytes = 0, slines = 0, sbytes = 0, i;
+ /* prefix char pointer for msmall and mlarge */
+ const char *pp1, *pp2;
+ /* suffix char pointer for msmall and mlarge */
+ const char *ps1, *ps2;
+
+ /* reserved must >= 0 for the line boundary adjustment to work */
+ if (reserved < 0)
+ reserved = 0;
+
+ if (mf1->size < mf2->size) {
+ memcpy(&msmall, mf1, sizeof(mmfile_t));
+ memcpy(&mlarge, mf2, sizeof(mmfile_t));
+ } else {
+ memcpy(&msmall, mf2, sizeof(mmfile_t));
+ memcpy(&mlarge, mf1, sizeof(mmfile_t));
+ }
+
+ pp1 = msmall.ptr, pp2 = mlarge.ptr;
+ for (i = 0; i < msmall.size && *pp1 == *pp2; ++i) {
+ plines += (*pp1 == '\n');
+ pp1++, pp2++;
+ }
+
+ ps1 = msmall.ptr + msmall.size - 1, ps2 = mlarge.ptr + mlarge.size - 1;
+ while (ps1 > pp1 && *ps1 == *ps2) {
+ slines += (*ps1 == '\n');
+ ps1--, ps2--;
+ }
+
+ /* Retract common prefix and suffix boundaries for reserved lines */
+ if (plines <= reserved + 1) {
+ plines = 0;
+ } else {
+ i = 0;
+ while (i <= reserved) {
+ pp1--;
+ i += (*pp1 == '\n');
+ }
+ /* The new mmfile starts at the next char just after '\n' */
+ pbytes = pp1 - msmall.ptr + 1;
+ plines -= reserved;
+ }
+
+ if (slines <= reserved + 1) {
+ slines = 0;
+ } else {
+ /* Note: with compiler SIMD support (ex. -O3 -mavx2), this
+ * might perform better than memchr. */
+ i = 0;
+ while (i <= reserved) {
+ ps1++;
+ i += (*ps1 == '\n');
+ }
+ /* The new mmfile includes this '\n' */
+ sbytes = msmall.ptr + msmall.size - ps1 - 1;
+ slines -= reserved;
+ if (msmall.ptr[msmall.size - 1] == '\n')
+ slines -= 1;
+ }
+
+ xe->nprefix = plines;
+ xe->nsuffix = slines;
+ out_mf1->ptr = mf1->ptr + pbytes;
+ out_mf1->size = mf1->size - pbytes - sbytes;
+ out_mf2->ptr = mf2->ptr + pbytes;
+ out_mf2->size = mf2->size - pbytes - sbytes;
+}
+
+
static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
xdlclassifier_t *cf, xdfile_t *xdf) {
unsigned int hbits;
@@ -254,10 +335,13 @@
xdl_cha_free(&xdf->rcha);
}
+/* Reserved lines for trimming, to leave room for shifting */
+#define TRIM_RESERVED_LINES 100
int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
xdfenv_t *xe) {
long enl1, enl2, sample;
+ mmfile_t tmf1, tmf2;
xdlclassifier_t cf;
memset(&cf, 0, sizeof(cf));
@@ -270,12 +354,14 @@
if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
return -1;
- if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
+ xdl_trim_files(mf1, mf2, TRIM_RESERVED_LINES, xe, &tmf1, &tmf2);
+
+ if (xdl_prepare_ctx(1, &tmf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
xdl_free_classifier(&cf);
return -1;
}
- if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
+ if (xdl_prepare_ctx(2, &tmf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
xdl_free_ctx(&xe->xdf1);
xdl_free_classifier(&cf);
diff --git a/mercurial/thirdparty/xdiff/xdiffi.c b/mercurial/thirdparty/xdiff/xdiffi.c
--- a/mercurial/thirdparty/xdiff/xdiffi.c
+++ b/mercurial/thirdparty/xdiff/xdiffi.c
@@ -1062,6 +1062,7 @@
static int xdl_call_hunk_func(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
xdemitconf_t const *xecfg)
{
+ long p = xe->nprefix, s = xe->nsuffix;
xdchange_t *xch, *xche;
if (!xecfg->hunk_func)
@@ -1073,23 +1074,29 @@
xche = xdl_get_hunk(&xch, xecfg);
if (!xch)
break;
+ if (xch != xche)
+ xdl_bug("xch != xche");
+ xch->i1 += p;
+ xch->i2 += p;
if (xch->i1 > i1 || xch->i2 > i2) {
if (xecfg->hunk_func(i1, xch->i1, i2, xch->i2, ecb->priv) < 0)
return -1;
}
i1 = xche->i1 + xche->chg1;
i2 = xche->i2 + xche->chg2;
}
- if (xecfg->hunk_func(i1, n1, i2, n2, ecb->priv) < 0)
+ if (xecfg->hunk_func(i1, n1 + p + s, i2, n2 + p + s,
+ ecb->priv) < 0)
return -1;
} else {
for (xch = xscr; xch; xch = xche->next) {
xche = xdl_get_hunk(&xch, xecfg);
if (!xch)
break;
- if (xecfg->hunk_func(
- xch->i1, xche->i1 + xche->chg1 - xch->i1,
- xch->i2, xche->i2 + xche->chg2 - xch->i2,
+ if (xecfg->hunk_func(xch->i1 + p,
+ xche->i1 + xche->chg1 - xch->i1,
+ xch->i2 + p,
+ xche->i2 + xche->chg2 - xch->i2,
ecb->priv) < 0)
return -1;
}
To: quark, #hg-reviewers, indygreg
Cc: indygreg, mercurial-devel
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