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xdiff: delete redundant array xdfile_t.ha

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When 0 <= i < xdfile_t.nreff the following is true:
xdfile_t.ha[i] == xdfile_t.recs[xdfile_t.rindex[i]]

This makes the code about 5% slower. The fields rindex and ha are
specific to the classic diff (myers and minimal). I plan on creating a
struct for classic diff, but there's a lot of cleanup that needs to be
done before that can happen and leaving ha in would make those cleanups
harder to follow.

A subsequent commit will delete the chastore cha from xdfile_t. That
later commit will investigate deleting ha and cha independently and
together.

Signed-off-by: Ezekiel Newren <ezekielnewren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ezekiel Newren 2025-09-26 22:41:54 +00:00 committed by Junio C Hamano
parent f4ea812b2d
commit 5c294dceb2
3 changed files with 16 additions and 21 deletions
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24
xdiff/xdiffi.c
View File

@ -22,6 +22,11 @@
#include "xinclude.h"
static unsigned long get_hash(xdfile_t *xdf, long index)
{
return xdf->recs[xdf->rindex[index]]->ha;
}
#define XDL_MAX_COST_MIN 256
#define XDL_HEUR_MIN_COST 256
#define XDL_LINE_MAX (long)((1UL << (CHAR_BIT * sizeof(long) - 1)) - 1)
@ -42,8 +47,8 @@ typedef struct s_xdpsplit {
* using this algorithm, so a little bit of heuristic is needed to cut the
* search and to return a suboptimal point.
*/
static long xdl_split(unsigned long const *ha1, long off1, long lim1,
unsigned long const *ha2, long off2, long lim2,
static long xdl_split(xdfile_t *xdf1, long off1, long lim1,
xdfile_t *xdf2, long off2, long lim2,
long *kvdf, long *kvdb, int need_min, xdpsplit_t *spl,
xdalgoenv_t *xenv) {
long dmin = off1 - lim2, dmax = lim1 - off2;
@ -87,7 +92,7 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
i1 = kvdf[d + 1];
prev1 = i1;
i2 = i1 - d;
for (; i1 < lim1 && i2 < lim2 && ha1[i1] == ha2[i2]; i1++, i2++);
for (; i1 < lim1 && i2 < lim2 && get_hash(xdf1, i1) == get_hash(xdf2, i2); i1++, i2++);
if (i1 - prev1 > xenv->snake_cnt)
got_snake = 1;
kvdf[d] = i1;
@ -124,7 +129,7 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
i1 = kvdb[d + 1] - 1;
prev1 = i1;
i2 = i1 - d;
for (; i1 > off1 && i2 > off2 && ha1[i1 - 1] == ha2[i2 - 1]; i1--, i2--);
for (; i1 > off1 && i2 > off2 && get_hash(xdf1, i1 - 1) == get_hash(xdf2, i2 - 1); i1--, i2--);
if (prev1 - i1 > xenv->snake_cnt)
got_snake = 1;
kvdb[d] = i1;
@ -159,7 +164,7 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
if (v > XDL_K_HEUR * ec && v > best &&
off1 + xenv->snake_cnt <= i1 && i1 < lim1 &&
off2 + xenv->snake_cnt <= i2 && i2 < lim2) {
for (k = 1; ha1[i1 - k] == ha2[i2 - k]; k++)
for (k = 1; get_hash(xdf1, i1 - k) == get_hash(xdf2, i2 - k); k++)
if (k == xenv->snake_cnt) {
best = v;
spl->i1 = i1;
@ -183,7 +188,7 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
if (v > XDL_K_HEUR * ec && v > best &&
off1 < i1 && i1 <= lim1 - xenv->snake_cnt &&
off2 < i2 && i2 <= lim2 - xenv->snake_cnt) {
for (k = 0; ha1[i1 + k] == ha2[i2 + k]; k++)
for (k = 0; get_hash(xdf1, i1 + k) == get_hash(xdf2, i2 + k); k++)
if (k == xenv->snake_cnt - 1) {
best = v;
spl->i1 = i1;
@ -260,13 +265,12 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
int xdl_recs_cmp(xdfile_t *xdf1, long off1, long lim1,
xdfile_t *xdf2, long off2, long lim2,
long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) {
unsigned long const *ha1 = xdf1->ha, *ha2 = xdf2->ha;
/*
* Shrink the box by walking through each diagonal snake (SW and NE).
*/
for (; off1 < lim1 && off2 < lim2 && ha1[off1] == ha2[off2]; off1++, off2++);
for (; off1 < lim1 && off2 < lim2 && ha1[lim1 - 1] == ha2[lim2 - 1]; lim1--, lim2--);
for (; off1 < lim1 && off2 < lim2 && get_hash(xdf1, off1) == get_hash(xdf2, off2); off1++, off2++);
for (; off1 < lim1 && off2 < lim2 && get_hash(xdf1, lim1 - 1) == get_hash(xdf2, lim2 - 1); lim1--, lim2--);
/*
* If one dimension is empty, then all records on the other one must
@ -285,7 +289,7 @@ int xdl_recs_cmp(xdfile_t *xdf1, long off1, long lim1,
/*
* Divide ...
*/
if (xdl_split(ha1, off1, lim1, ha2, off2, lim2, kvdf, kvdb,
if (xdl_split(xdf1, off1, lim1, xdf2, off2, lim2, kvdf, kvdb,
need_min, &spl, xenv) < 0) {
return -1;

12
xdiff/xprepare.c
View File

@ -133,7 +133,6 @@ static void xdl_free_ctx(xdfile_t *xdf)
{
xdl_free(xdf->rindex);
xdl_free(xdf->rchg - 1);
xdl_free(xdf->ha);
xdl_free(xdf->recs);
xdl_cha_free(&xdf->rcha);
}
@ -146,7 +145,6 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
char const *blk, *cur, *top, *prev;
xrecord_t *crec;
xdf->ha = NULL;
xdf->rindex = NULL;
xdf->rchg = NULL;
xdf->recs = NULL;
@ -181,8 +179,6 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
if (!XDL_ALLOC_ARRAY(xdf->rindex, xdf->nrec + 1))
goto abort;
if (!XDL_ALLOC_ARRAY(xdf->ha, xdf->nrec + 1))
goto abort;
}
xdf->rchg += 1;
@ -300,9 +296,7 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
i <= xdf1->dend; i++, recs++) {
if (dis1[i] == 1 ||
(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
xdf1->rindex[nreff] = i;
xdf1->ha[nreff] = (*recs)->ha;
nreff++;
xdf1->rindex[nreff++] = i;
} else
xdf1->rchg[i] = 1;
}
@ -312,9 +306,7 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
i <= xdf2->dend; i++, recs++) {
if (dis2[i] == 1 ||
(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
xdf2->rindex[nreff] = i;
xdf2->ha[nreff] = (*recs)->ha;
nreff++;
xdf2->rindex[nreff++] = i;
} else
xdf2->rchg[i] = 1;
}

1
xdiff/xtypes.h
View File

@ -52,7 +52,6 @@ typedef struct s_xdfile {
char *rchg;
long *rindex;
long nreff;
unsigned long *ha;
} xdfile_t;
typedef struct s_xdfenv {