}
        if (!oidcmp(&two->object.oid, &shifted))
                return two;
-       return lookup_tree(shifted.hash);
+       return lookup_tree(&shifted);
 }
 
 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
                return NULL;
        }
 
-       result = lookup_tree(active_cache_tree->sha1);
+       result = lookup_tree(&active_cache_tree->oid);
 
        return result;
 }
        opts.show_rename_progress = o->show_rename_progress;
        opts.output_format = DIFF_FORMAT_NO_OUTPUT;
        diff_setup_done(&opts);
-       diff_tree_sha1(o_tree->object.oid.hash, tree->object.oid.hash, "", &opts);
+       diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
        diffcore_std(&opts);
        if (opts.needed_rename_limit > o->needed_rename_limit)
                o->needed_rename_limit = opts.needed_rename_limit;
                                return ret;
                        result->clean = (merge_status == 0);
                } else if (S_ISGITLINK(a->mode)) {
-                       result->clean = merge_submodule(result->oid.hash,
+                       result->clean = merge_submodule(&result->oid,
                                                       one->path,
-                                                      one->oid.hash,
-                                                      a->oid.hash,
-                                                      b->oid.hash,
+                                                      &one->oid,
+                                                      &a->oid,
+                                                      &b->oid,
                                                       !o->call_depth);
                } else if (S_ISLNK(a->mode)) {
                        oidcpy(&result->oid, &a->oid);
         * performed.  Comparison can be skipped if both files are
         * unchanged since their sha1s have already been compared.
         */
-       if (renormalize_buffer(path, o.buf, o.len, &o) |
-           renormalize_buffer(path, a.buf, a.len, &a))
+       if (renormalize_buffer(&the_index, path, o.buf, o.len, &o) |
+           renormalize_buffer(&the_index, path, a.buf, a.len, &a))
                ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
 
 error_return:
                /* if there is no common ancestor, use an empty tree */
                struct tree *tree;
 
-               tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
+               tree = lookup_tree(&empty_tree_oid);
                merged_common_ancestors = make_virtual_commit(tree, "ancestor");
        }
 
 {
        struct object *object;
 
-       object = deref_tag(parse_object(oid->hash), name, strlen(name));
+       object = deref_tag(parse_object(oid), name, strlen(name));
        if (!object)
                return NULL;
        if (object->type == OBJ_TREE)
                o->xdl_opts |= value;
        }
        else if (!strcmp(s, "ignore-space-change"))
-               o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
+               DIFF_XDL_SET(o, IGNORE_WHITESPACE_CHANGE);
        else if (!strcmp(s, "ignore-all-space"))
-               o->xdl_opts |= XDF_IGNORE_WHITESPACE;
+               DIFF_XDL_SET(o, IGNORE_WHITESPACE);
        else if (!strcmp(s, "ignore-space-at-eol"))
-               o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
+               DIFF_XDL_SET(o, IGNORE_WHITESPACE_AT_EOL);
        else if (!strcmp(s, "renormalize"))
                o->renormalize = 1;
        else if (!strcmp(s, "no-renormalize"))