#include "cache.h"
 #include "tag.h"
 #include "commit.h"
+#include "commit-graph.h"
 #include "pkt-line.h"
 #include "utf8.h"
 #include "diff.h"
        if (!ret) {
                enum object_type type;
                unsigned long size;
-               ret = read_sha1_file(commit->object.oid.hash, &type, &size);
+               ret = read_object_file(&commit->object.oid, &type, &size);
                if (!ret)
                        die("cannot read commit object %s",
                            oid_to_hex(&commit->object.oid));
                return -1;
        if (item->object.parsed)
                return 0;
-       buffer = read_sha1_file(item->object.oid.hash, &type, &size);
+       if (parse_commit_in_graph(item))
+               return 0;
+       buffer = read_object_file(&item->object.oid, &type, &size);
        if (!buffer)
                return quiet_on_missing ? -1 :
                        error("Could not read %s",
        desc = merge_remote_util(parent);
        if (!desc || !desc->obj)
                return;
-       buf = read_sha1_file(desc->obj->oid.hash, &type, &size);
+       buf = read_object_file(&desc->obj->oid, &type, &size);
        if (!buf || type != OBJ_TAG)
                goto free_return;
        len = parse_signature(buf, size);
        int encoding_is_utf8;
        struct strbuf buffer;
 
-       assert_sha1_type(tree->hash, OBJ_TREE);
+       assert_oid_type(tree, OBJ_TREE);
 
        if (memchr(msg, '\0', msg_len))
                return error("a NUL byte in commit log message not allowed.");