xdiff/xmerge.c: use memset() instead of explicit for-loop

memset() is heavily optimized, and resulting assembler code
is about 150 lines less for that file.

Signed-off-by: Alexey Mahotkin <squadette@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

xdiff/xmerge.c

@@ -152,7 +152,6 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 	int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 	int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 	int marker3_size = (name3 ? strlen(name3) + 1 : 0);
-	int j;
 
 	if (marker_size <= 0)
 		marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
@@ -164,8 +163,8 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 	if (!dest) {
 		size += marker_size + 1 + marker1_size;
 	} else {
-		for (j = 0; j < marker_size; j++)
-			dest[size++] = '<';
+		memset(dest + size, '<', marker_size);
+		size += marker_size;
 		if (marker1_size) {
 			dest[size] = ' ';
 			memcpy(dest + size + 1, name1, marker1_size - 1);
@@ -183,8 +182,8 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 		if (!dest) {
 			size += marker_size + 1 + marker3_size;
 		} else {
-			for (j = 0; j < marker_size; j++)
-				dest[size++] = '|';
+			memset(dest + size, '|', marker_size);
+			size += marker_size;
 			if (marker3_size) {
 				dest[size] = ' ';
 				memcpy(dest + size + 1, name3, marker3_size - 1);
@@ -199,8 +198,8 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 	if (!dest) {
 		size += marker_size + 1;
 	} else {
-		for (j = 0; j < marker_size; j++)
-			dest[size++] = '=';
+		memset(dest + size, '=', marker_size);
+		size += marker_size;
 		dest[size++] = '\n';
 	}
 
@@ -210,8 +209,8 @@ static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 	if (!dest) {
 		size += marker_size + 1 + marker2_size;
 	} else {
-		for (j = 0; j < marker_size; j++)
-			dest[size++] = '>';
+		memset(dest + size, '>', marker_size);
+		size += marker_size;
 		if (marker2_size) {
 			dest[size] = ' ';
 			memcpy(dest + size + 1, name2, marker2_size - 1);