xdiff/xprepare: use memset()

Use memset() instead of a for loop to initialize. This could give a
performance advantage.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

xdiff/xprepare.c

@@ -64,8 +64,6 @@ static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
 
 
 static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
-	long i;
-
 	cf->flags = flags;
 
 	cf->hbits = xdl_hashbits((unsigned int) size);
@@ -80,8 +78,7 @@ static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
 		xdl_cha_free(&cf->ncha);
 		return -1;
 	}
-	for (i = 0; i < cf->hsize; i++)
-		cf->rchash[i] = NULL;
+	memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
 
 	cf->count = 0;
 
@@ -136,7 +133,7 @@ static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned
 static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 			   xdlclassifier_t *cf, xdfile_t *xdf) {
 	unsigned int hbits;
-	long i, nrec, hsize, bsize;
+	long nrec, hsize, bsize;
 	unsigned long hav;
 	char const *blk, *cur, *top, *prev;
 	xrecord_t *crec;
@@ -164,8 +161,7 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 		xdl_cha_free(&xdf->rcha);
 		return -1;
 	}
-	for (i = 0; i < hsize; i++)
-		rhash[i] = NULL;
+	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;
 	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {