Merge branch 'rs/ls-files-partial-optim'

"ls-files" run with pathspec has been micro-optimized to avoid
having to memmove(3) unnecessary bytes.

* rs/ls-files-partial-optim:
  ls-files: move only kept cache entries in prune_cache()
  ls-files: pass prefix length explicitly to prune_cache()

builtin/ls-files.c

@@ -369,28 +369,30 @@ static void show_files(struct dir_struct *dir)
 /*
  * Prune the index to only contain stuff starting with "prefix"
  */
-static void prune_cache(const char *prefix)
+static void prune_cache(const char *prefix, size_t prefixlen)
 {
-	int pos = cache_name_pos(prefix, max_prefix_len);
+	int pos;
 	unsigned int first, last;
 
+	if (!prefix)
+		return;
+	pos = cache_name_pos(prefix, prefixlen);
 	if (pos < 0)
 		pos = -pos-1;
-	memmove(active_cache, active_cache + pos,
-		(active_nr - pos) * sizeof(struct cache_entry *));
-	active_nr -= pos;
-	first = 0;
+	first = pos;
 	last = active_nr;
 	while (last > first) {
 		int next = (last + first) >> 1;
 		const struct cache_entry *ce = active_cache[next];
-		if (!strncmp(ce->name, prefix, max_prefix_len)) {
+		if (!strncmp(ce->name, prefix, prefixlen)) {
 			first = next+1;
 			continue;
 		}
 		last = next;
 	}
-	active_nr = last;
+	memmove(active_cache, active_cache + pos,
+		(last - pos) * sizeof(struct cache_entry *));
+	active_nr = last - pos;
 }
 
 /*
@@ -641,8 +643,7 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 	      show_killed || show_modified || show_resolve_undo))
 		show_cached = 1;
 
-	if (max_prefix)
-		prune_cache(max_prefix);
+	prune_cache(max_prefix, max_prefix_len);
 	if (with_tree) {
 		/*
 		 * Basic sanity check; show-stages and show-unmerged