Shrink "struct object" a bit

This shrinks "struct object" by a small amount, by getting rid of the
"struct type *" pointer and replacing it with a 3-bit bitfield instead.

In addition, we merge the bitfields and the "flags" field, which
incidentally should also remove a useless 4-byte padding from the object
when in 64-bit mode.

Now, our "struct object" is still too damn large, but it's now less
obviously bloated, and of the remaining fields, only the "util" (which is
not used by most things) is clearly something that should be eventually
discarded.

This shrinks the "git-rev-list --all" memory use by about 2.5% on the
kernel archive (and, perhaps more importantly, on the larger mozilla
archive). That may not sound like much, but I suspect it's more on a
64-bit platform.

There are other remaining inefficiencies (the parent lists, for example,
probably have horrible malloc overhead), but this was pretty obvious.

Most of the patch is just changing the comparison of the "type" pointer
from one of the constant string pointers to the appropriate new TYPE_xxx
small integer constant.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

21 files changed, 113 insertions, 96 deletions

diff --git a/blob.c b/blob.c
index c1fdd861c3..7377008744 100644
--- a/blob.c
+++ b/blob.c
@@ -10,14 +10,14 @@ struct blob *lookup_blob(const unsigned char *sha1)
 	if (!obj) {
 		struct blob *ret = xcalloc(1, sizeof(struct blob));
 		created_object(sha1, &ret->object);
-		ret->object.type = blob_type;
+		ret->object.type = TYPE_BLOB;
 		return ret;
 	}
 	if (!obj->type)
-		obj->type = blob_type;
-	if (obj->type != blob_type) {
-		error("Object %s is a %s, not a blob", 
-		      sha1_to_hex(sha1), obj->type);
+		obj->type = TYPE_BLOB;
+	if (obj->type != TYPE_BLOB) {
+		error("Object %s is a %s, not a blob",
+		      sha1_to_hex(sha1), typename(obj->type));
 		return NULL;
 	}
 	return (struct blob *) obj;
diff --git a/builtin-diff.c b/builtin-diff.c
index 27451d5613..6ac3d4b8ca 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -303,9 +303,9 @@ int cmd_diff(int argc, const char **argv, char **envp)
 		obj = deref_tag(obj, NULL, 0);
 		if (!obj)
 			die("invalid object '%s' given.", name);
-		if (!strcmp(obj->type, commit_type))
+		if (obj->type == TYPE_COMMIT)
 			obj = &((struct commit *)obj)->tree->object;
-		if (!strcmp(obj->type, tree_type)) {
+		if (obj->type == TYPE_TREE) {
 			if (ARRAY_SIZE(ent) <= ents)
 				die("more than %d trees given: '%s'",
 				    (int) ARRAY_SIZE(ent), name);
@@ -315,7 +315,7 @@ int cmd_diff(int argc, const char **argv, char **envp)
 			ents++;
 			continue;
 		}
-		if (!strcmp(obj->type, blob_type)) {
+		if (obj->type == TYPE_BLOB) {
 			if (2 <= blobs)
 				die("more than two blobs given: '%s'", name);
 			memcpy(blob[blobs].sha1, obj->sha1, 20);
diff --git a/builtin-grep.c b/builtin-grep.c
index 5fac5701e6..9806499263 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -630,10 +630,9 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
 static int grep_object(struct grep_opt *opt, const char **paths,
 		       struct object *obj, const char *name)
 {
-	if (!strcmp(obj->type, blob_type))
+	if (obj->type == TYPE_BLOB)
 		return grep_sha1(opt, obj->sha1, name);
-	if (!strcmp(obj->type, commit_type) ||
-	    !strcmp(obj->type, tree_type)) {
+	if (obj->type == TYPE_COMMIT || obj->type == TYPE_TREE) {
 		struct tree_desc tree;
 		void *data;
 		int hit;
@@ -646,7 +645,7 @@ static int grep_object(struct grep_opt *opt, const char **paths,
 		free(data);
 		return hit;
 	}
-	die("unable to grep from object of type %s", obj->type);
+	die("unable to grep from object of type %s", typename(obj->type));
 }
 
 static const char builtin_grep_usage[] =
diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index e885624255..2b298c4e41 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c
@@ -158,16 +158,16 @@ static void show_commit_list(struct rev_info *revs)
 		const char *name = pending->name;
 		if (obj->flags & (UNINTERESTING | SEEN))
 			continue;
-		if (obj->type == tag_type) {
+		if (obj->type == TYPE_TAG) {
 			obj->flags |= SEEN;
 			p = add_object(obj, p, NULL, name);
 			continue;
 		}
-		if (obj->type == tree_type) {
+		if (obj->type == TYPE_TREE) {
 			p = process_tree((struct tree *)obj, p, NULL, name);
 			continue;
 		}
-		if (obj->type == blob_type) {
+		if (obj->type == TYPE_BLOB) {
 			p = process_blob((struct blob *)obj, p, NULL, name);
 			continue;
 		}
diff --git a/builtin-show-branch.c b/builtin-show-branch.c
index 2895140915..cf9c071a53 100644
--- a/builtin-show-branch.c
+++ b/builtin-show-branch.c
@@ -15,7 +15,7 @@ static const char **default_arg = NULL;
 #define UNINTERESTING	01
 
 #define REV_SHIFT	 2
-#define MAX_REVS	29 /* should not exceed bits_per_int - REV_SHIFT */
+#define MAX_REVS	(FLAG_BITS - REV_SHIFT) /* should not exceed bits_per_int - REV_SHIFT */
 
 static struct commit *interesting(struct commit_list *list)
 {
diff --git a/commit.c b/commit.c
index 94f470b75c..11fca559d8 100644
--- a/commit.c
+++ b/commit.c
@@ -56,10 +56,10 @@ static struct commit *check_commit(struct object *obj,
 				   const unsigned char *sha1,
 				   int quiet)
 {
-	if (obj->type != commit_type) {
+	if (obj->type != TYPE_COMMIT) {
 		if (!quiet)
 			error("Object %s is a %s, not a commit",
-			      sha1_to_hex(sha1), obj->type);
+			      sha1_to_hex(sha1), typename(obj->type));
 		return NULL;
 	}
 	return (struct commit *) obj;
@@ -86,11 +86,11 @@ struct commit *lookup_commit(const unsigned char *sha1)
 	if (!obj) {
 		struct commit *ret = xcalloc(1, sizeof(struct commit));
 		created_object(sha1, &ret->object);
-		ret->object.type = commit_type;
+		ret->object.type = TYPE_COMMIT;
 		return ret;
 	}
 	if (!obj->type)
-		obj->type = commit_type;
+		obj->type = TYPE_COMMIT;
 	return check_commit(obj, sha1, 0);
 }
 
diff --git a/describe.c b/describe.c
index 8a9cd5d52c..aa3434a4cb 100644
--- a/describe.c
+++ b/describe.c
@@ -67,7 +67,7 @@ static int get_name(const char *path, const unsigned char *sha1)
 	 * Otherwise only annotated tags are used.
 	 */
 	if (!strncmp(path, "refs/tags/", 10)) {
-		if (object->type == tag_type)
+		if (object->type == TYPE_TAG)
 			prio = 2;
 		else
 			prio = 1;
diff --git a/fetch-pack.c b/fetch-pack.c
index 8371348556..7d23a8071a 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -46,7 +46,7 @@ static int rev_list_insert_ref(const char *path, const unsigned char *sha1)
 {
 	struct object *o = deref_tag(parse_object(sha1), path, 0);
 
-	if (o && o->type == commit_type)
+	if (o && o->type == TYPE_COMMIT)
 		rev_list_push((struct commit *)o, SEEN);
 
 	return 0;
@@ -251,14 +251,14 @@ static int mark_complete(const char *path, const unsigned char *sha1)
 {
 	struct object *o = parse_object(sha1);
 
-	while (o && o->type == tag_type) {
+	while (o && o->type == TYPE_TAG) {
 		struct tag *t = (struct tag *) o;
 		if (!t->tagged)
 			break; /* broken repository */
 		o->flags |= COMPLETE;
 		o = parse_object(t->tagged->sha1);
 	}
-	if (o && o->type == commit_type) {
+	if (o && o->type == TYPE_COMMIT) {
 		struct commit *commit = (struct commit *)o;
 		commit->object.flags |= COMPLETE;
 		insert_by_date(commit, &complete);
@@ -352,7 +352,7 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
 		 * in sync with the other side at some time after
 		 * that (it is OK if we guess wrong here).
 		 */
-		if (o->type == commit_type) {
+		if (o->type == TYPE_COMMIT) {
 			struct commit *commit = (struct commit *)o;
 			if (!cutoff || cutoff < commit->date)
 				cutoff = commit->date;
@@ -371,7 +371,7 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
 		struct object *o = deref_tag(lookup_object(ref->old_sha1),
 					     NULL, 0);
 
-		if (!o || o->type != commit_type || !(o->flags & COMPLETE))
+		if (!o || o->type != TYPE_COMMIT || !(o->flags & COMPLETE))
 			continue;
 
 		if (!(o->flags & SEEN)) {
diff --git a/fetch.c b/fetch.c
index cf6c99490c..238032b798 100644
--- a/fetch.c
+++ b/fetch.c
@@ -118,27 +118,27 @@ static struct object_list **process_queue_end = &process_queue;
 
 static int process_object(struct object *obj)
 {
-	if (obj->type == commit_type) {
+	if (obj->type == TYPE_COMMIT) {
 		if (process_commit((struct commit *)obj))
 			return -1;
 		return 0;
 	}
-	if (obj->type == tree_type) {
+	if (obj->type == TYPE_TREE) {
 		if (process_tree((struct tree *)obj))
 			return -1;
 		return 0;
 	}
-	if (obj->type == blob_type) {
+	if (obj->type == TYPE_BLOB) {
 		return 0;
 	}
-	if (obj->type == tag_type) {
+	if (obj->type == TYPE_TAG) {
 		if (process_tag((struct tag *)obj))
 			return -1;
 		return 0;
 	}
 	return error("Unable to determine requirements "
 		     "of type %s for %s",
-		     obj->type, sha1_to_hex(obj->sha1));
+		     typename(obj->type), sha1_to_hex(obj->sha1));
 }
 
 static int process(struct object *obj)
@@ -179,9 +179,7 @@ static int loop(void)
 		 */
 		if (! (obj->flags & TO_SCAN)) {
 			if (fetch(obj->sha1)) {
-				report_missing(obj->type
-					       ? obj->type
-					       : "object", obj->sha1);
+				report_missing(typename(obj->type), obj->sha1);
 				return -1;
 			}
 		}
diff --git a/fsck-objects.c b/fsck-objects.c
index 33ce366e99..2b1aab488f 100644
--- a/fsck-objects.c
+++ b/fsck-objects.c
@@ -34,7 +34,7 @@ static void objreport(struct object *obj, const char *severity,
                       const char *err, va_list params)
 {
 	fprintf(stderr, "%s in %s %s: ",
-	        severity, obj->type, sha1_to_hex(obj->sha1));
+	        severity, typename(obj->type), sha1_to_hex(obj->sha1));
 	vfprintf(stderr, err, params);
 	fputs("\n", stderr);
 }
@@ -74,7 +74,7 @@ static void check_connectivity(void)
 				; /* it is in pack */
 			else
 				printf("missing %s %s\n",
-				       obj->type, sha1_to_hex(obj->sha1));
+				       typename(obj->type), sha1_to_hex(obj->sha1));
 			continue;
 		}
 
@@ -87,20 +87,20 @@ static void check_connectivity(void)
 				    (has_sha1_file(ref->sha1)))
 					continue;
 				printf("broken link from %7s %s\n",
-				       obj->type, sha1_to_hex(obj->sha1));
+				       typename(obj->type), sha1_to_hex(obj->sha1));
 				printf("              to %7s %s\n",
-				       ref->type, sha1_to_hex(ref->sha1));
+				       typename(ref->type), sha1_to_hex(ref->sha1));
 			}
 		}
 
 		if (show_unreachable && !(obj->flags & REACHABLE)) {
 			printf("unreachable %s %s\n",
-			       obj->type, sha1_to_hex(obj->sha1));
+			       typename(obj->type), sha1_to_hex(obj->sha1));
 			continue;
 		}
 
 		if (!obj->used) {
-			printf("dangling %s %s\n", obj->type, 
+			printf("dangling %s %s\n", typename(obj->type),
 			       sha1_to_hex(obj->sha1));
 		}
 	}
@@ -282,7 +282,7 @@ static int fsck_tag(struct tag *tag)
 	if (!show_tags)
 		return 0;
 
-	printf("tagged %s %s", tagged->type, sha1_to_hex(tagged->sha1));
+	printf("tagged %s %s", typename(tagged->type), sha1_to_hex(tagged->sha1));
 	printf(" (%s) in %s\n", tag->tag, sha1_to_hex(tag->object.sha1));
 	return 0;
 }
@@ -295,16 +295,16 @@ static int fsck_sha1(unsigned char *sha1)
 	if (obj->flags & SEEN)
 		return 0;
 	obj->flags |= SEEN;
-	if (obj->type == blob_type)
+	if (obj->type == TYPE_BLOB)
 		return 0;
-	if (obj->type == tree_type)
+	if (obj->type == TYPE_TREE)
 		return fsck_tree((struct tree *) obj);
-	if (obj->type == commit_type)
+	if (obj->type == TYPE_COMMIT)
 		return fsck_commit((struct commit *) obj);
-	if (obj->type == tag_type)
+	if (obj->type == TYPE_TAG)
 		return fsck_tag((struct tag *) obj);
 	/* By now, parse_object() would've returned NULL instead. */
-	return objerror(obj, "unknown type '%s' (internal fsck error)", obj->type);
+	return objerror(obj, "unknown type '%d' (internal fsck error)", obj->type);
 }
 
 /*
@@ -470,7 +470,7 @@ static int fsck_cache_tree(struct cache_tree *it)
 		}
 		mark_reachable(obj, REACHABLE);
 		obj->used = 1;
-		if (obj->type != tree_type)
+		if (obj->type != TYPE_TREE)
 			err |= objerror(obj, "non-tree in cache-tree");
 	}
 	for (i = 0; i < it->subtree_nr; i++)
diff --git a/http-push.c b/http-push.c
index 2d9441ec60..ba64f8fff5 100644
--- a/http-push.c
+++ b/http-push.c
@@ -1773,16 +1773,16 @@ static int get_delta(struct rev_info *revs, struct remote_lock *lock)
 
 		if (obj->flags & (UNINTERESTING | SEEN))
 			continue;
-		if (obj->type == tag_type) {
+		if (obj->type == TYPE_TAG) {
 			obj->flags |= SEEN;
 			p = add_object(obj, p, NULL, name);
 			continue;
 		}
-		if (obj->type == tree_type) {
+		if (obj->type == TYPE_TREE) {
 			p = process_tree((struct tree *)obj, p, NULL, name);
 			continue;
 		}
-		if (obj->type == blob_type) {
+		if (obj->type == TYPE_BLOB) {
 			p = process_blob((struct blob *)obj, p, NULL, name);
 			continue;
 		}
@@ -1949,12 +1949,12 @@ static int ref_newer(const unsigned char *new_sha1,
 	 * old.  Otherwise we require --force.
 	 */
 	o = deref_tag(parse_object(old_sha1), NULL, 0);
-	if (!o || o->type != commit_type)
+	if (!o || o->type != TYPE_COMMIT)
 		return 0;
 	old = (struct commit *) o;
 
 	o = deref_tag(parse_object(new_sha1), NULL, 0);
-	if (!o || o->type != commit_type)
+	if (!o || o->type != TYPE_COMMIT)
 		return 0;
 	new = (struct commit *) o;
 
@@ -2033,7 +2033,7 @@ static void add_remote_info_ref(struct remote_ls_ctx *ls)
 	fwrite_buffer(ref_info, 1, len, buf);
 	free(ref_info);
 
-	if (o->type == tag_type) {
+	if (o->type == TYPE_TAG) {
 		o = deref_tag(o, ls->dentry_name, 0);
 		if (o) {
 			len = strlen(ls->dentry_name) + 45;
diff --git a/name-rev.c b/name-rev.c
index bad8a53777..1f0135f5ab 100644
--- a/name-rev.c
+++ b/name-rev.c
@@ -84,14 +84,14 @@ static int name_ref(const char *path, const unsigned char *sha1)
 	if (tags_only && strncmp(path, "refs/tags/", 10))
 		return 0;
 
-	while (o && o->type == tag_type) {
+	while (o && o->type == TYPE_TAG) {
 		struct tag *t = (struct tag *) o;
 		if (!t->tagged)
 			break; /* broken repository */
 		o = parse_object(t->tagged->sha1);
 		deref = 1;
 	}
-	if (o && o->type == commit_type) {
+	if (o && o->type == TYPE_COMMIT) {
 		struct commit *commit = (struct commit *)o;
 
 		if (!strncmp(path, "refs/heads/", 11))
@@ -167,7 +167,7 @@ int main(int argc, char **argv)
 		}
 
 		o = deref_tag(parse_object(sha1), *argv, 0);
-		if (!o || o->type != commit_type) {
+		if (!o || o->type != TYPE_COMMIT) {
 			fprintf(stderr, "Could not get commit for %s. Skipping.\n",
 					*argv);
 			continue;
diff --git a/object.c b/object.c
index 9adc87479b..0f70890a45 100644
--- a/object.c
+++ b/object.c
@@ -9,6 +9,10 @@ struct object **objs;
 static int nr_objs;
 int obj_allocs;
 
+const char *type_names[] = {
+	"none", "blob", "tree", "commit", "bad"
+};
+
 int track_object_refs = 0;
 
 static int hashtable_index(const unsigned char *sha1)
@@ -50,7 +54,7 @@ void created_object(const unsigned char *sha1, struct object *obj)
 
 	obj->parsed = 0;
 	memcpy(obj->sha1, sha1, 20);
-	obj->type = NULL;
+	obj->type = TYPE_NONE;
 	obj->refs = NULL;
 	obj->used = 0;
 
@@ -179,7 +183,7 @@ struct object *lookup_unknown_object(const unsigned char *sha1)
 	if (!obj) {
 		union any_object *ret = xcalloc(1, sizeof(*ret));
 		created_object(sha1, &ret->object);
-		ret->object.type = NULL;
+		ret->object.type = TYPE_NONE;
 		return &ret->object;
 	}
 	return obj;
diff --git a/object.h b/object.h
index e08afbd29f..a0762b6672 100644
--- a/object.h
+++ b/object.h
@@ -12,12 +12,22 @@ struct object_refs {
 	struct object *ref[FLEX_ARRAY]; /* more */
 };
 
+#define TYPE_BITS   3
+#define FLAG_BITS  27
+
+#define TYPE_NONE   0
+#define TYPE_BLOB   1
+#define TYPE_TREE   2
+#define TYPE_COMMIT 3
+#define TYPE_TAG    4
+#define TYPE_BAD    5
+
 struct object {
 	unsigned parsed : 1;
 	unsigned used : 1;
-	unsigned int flags;
+	unsigned type : TYPE_BITS;
+	unsigned flags : FLAG_BITS;
 	unsigned char sha1[20];
-	const char *type;
 	struct object_refs *refs;
 	void *util;
 };
@@ -25,6 +35,12 @@ struct object {
 extern int track_object_refs;
 extern int obj_allocs;
 extern struct object **objs;
+extern const char *type_names[];
+
+static inline const char *typename(unsigned int type)
+{
+	return type_names[type > TYPE_TAG ? TYPE_BAD : type];
+}
 
 /** Internal only **/
 struct object *lookup_object(const unsigned char *sha1);
diff --git a/revision.c b/revision.c
index 75c648c13c..82214eb71a 100644
--- a/revision.c
+++ b/revision.c
@@ -140,7 +140,7 @@ static struct commit *handle_commit(struct rev_info *revs, struct object *object
 	/*
 	 * Tag object? Look what it points to..
 	 */
-	while (object->type == tag_type) {
+	while (object->type == TYPE_TAG) {
 		struct tag *tag = (struct tag *) object;
 		if (revs->tag_objects && !(flags & UNINTERESTING))
 			add_pending_object(revs, object, tag->tag);
@@ -153,7 +153,7 @@ static struct commit *handle_commit(struct rev_info *revs, struct object *object
 	 * Commit object? Just return it, we'll do all the complex
 	 * reachability crud.
 	 */
-	if (object->type == commit_type) {
+	if (object->type == TYPE_COMMIT) {
 		struct commit *commit = (struct commit *)object;
 		if (parse_commit(commit) < 0)
 			die("unable to parse commit %s", name);
@@ -169,7 +169,7 @@ static struct commit *handle_commit(struct rev_info *revs, struct object *object
 	 * Tree object? Either mark it uniniteresting, or add it
 	 * to the list of objects to look at later..
 	 */
-	if (object->type == tree_type) {
+	if (object->type == TYPE_TREE) {
 		struct tree *tree = (struct tree *)object;
 		if (!revs->tree_objects)
 			return NULL;
@@ -184,7 +184,7 @@ static struct commit *handle_commit(struct rev_info *revs, struct object *object
 	/*
 	 * Blob object? You know the drill by now..
 	 */
-	if (object->type == blob_type) {
+	if (object->type == TYPE_BLOB) {
 		struct blob *blob = (struct blob *)object;
 		if (!revs->blob_objects)
 			return NULL;
@@ -498,11 +498,11 @@ static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 		return 0;
 	while (1) {
 		it = get_reference(revs, arg, sha1, 0);
-		if (strcmp(it->type, tag_type))
+		if (it->type != TYPE_TAG)
 			break;
 		memcpy(sha1, ((struct tag*)it)->tagged->sha1, 20);
 	}
-	if (strcmp(it->type, commit_type))
+	if (it->type != TYPE_COMMIT)
 		return 0;
 	commit = (struct commit *)it;
 	for (parents = commit->parents; parents; parents = parents->next) {
diff --git a/send-pack.c b/send-pack.c
index 409f188503..af93b11f23 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -151,12 +151,12 @@ static int ref_newer(const unsigned char *new_sha1,
 	 * old.  Otherwise we require --force.
 	 */
 	o = deref_tag(parse_object(old_sha1), NULL, 0);
-	if (!o || o->type != commit_type)
+	if (!o || o->type != TYPE_COMMIT)
 		return 0;
 	old = (struct commit *) o;
 
 	o = deref_tag(parse_object(new_sha1), NULL, 0);
-	if (!o || o->type != commit_type)
+	if (!o || o->type != TYPE_COMMIT)
 		return 0;
 	new = (struct commit *) o;
 
diff --git a/server-info.c b/server-info.c
index 05bce7da3b..0eb5132cc1 100644
--- a/server-info.c
+++ b/server-info.c
@@ -12,7 +12,7 @@ static int add_info_ref(const char *path, const unsigned char *sha1)
 	struct object *o = parse_object(sha1);
 
 	fprintf(info_ref_fp, "%s	%s\n", sha1_to_hex(sha1), path);
-	if (o->type == tag_type) {
+	if (o->type == TYPE_TAG) {
 		o = deref_tag(o, path, 0);
 		if (o)
 			fprintf(info_ref_fp, "%s	%s^{}\n",
diff --git a/sha1_name.c b/sha1_name.c
index 8fe9b7a75f..cd85d1fa0f 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -357,7 +357,7 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 {
 	unsigned char outer[20];
 	const char *sp;
-	const char *type_string = NULL;
+	unsigned int expected_type = 0;
 	struct object *o;
 
 	/*
@@ -381,13 +381,13 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 
 	sp++; /* beginning of type name, or closing brace for empty */
 	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
-		type_string = commit_type;
+		expected_type = TYPE_COMMIT;
 	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
-		type_string = tree_type;
+		expected_type = TYPE_TREE;
 	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
-		type_string = blob_type;
+		expected_type = TYPE_BLOB;
 	else if (sp[0] == '}')
-		type_string = NULL;
+		expected_type = TYPE_NONE;
 	else
 		return -1;
 
@@ -397,7 +397,7 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 	o = parse_object(outer);
 	if (!o)
 		return -1;
-	if (!type_string) {
+	if (!expected_type) {
 		o = deref_tag(o, name, sp - name - 2);
 		if (!o || (!o->parsed && !parse_object(o->sha1)))
 			return -1;
@@ -412,18 +412,18 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
 		while (1) {
 			if (!o || (!o->parsed && !parse_object(o->sha1)))
 				return -1;
-			if (o->type == type_string) {
+			if (o->type == expected_type) {
 				memcpy(sha1, o->sha1, 20);
 				return 0;
 			}
-			if (o->type == tag_type)
+			if (o->type == TYPE_TAG)
 				o = ((struct tag*) o)->tagged;
-			else if (o->type == commit_type)
+			else if (o->type == TYPE_COMMIT)
 				o = &(((struct commit *) o)->tree->object);
 			else
 				return error("%.*s: expected %s type, but the object dereferences to %s type",
-					     len, name, type_string,
-					     o->type);
+					     len, name, typename(expected_type),
+					     typename(o->type));
 			if (!o->parsed)
 				parse_object(o->sha1);
 		}
diff --git a/tag.c b/tag.c
index f390ee7030..9191333270 100644
--- a/tag.c
+++ b/tag.c
@@ -5,7 +5,7 @@ const char *tag_type = "tag";
 
 struct object *deref_tag(struct object *o, const char *warn, int warnlen)
 {
-	while (o && o->type == tag_type)
+	while (o && o->type == TYPE_TAG)
 		o = parse_object(((struct tag *)o)->tagged->sha1);
 	if (!o && warn) {
 		if (!warnlen)
@@ -21,14 +21,14 @@ struct tag *lookup_tag(const unsigned char *sha1)
         if (!obj) {
                 struct tag *ret = xcalloc(1, sizeof(struct tag));
                 created_object(sha1, &ret->object);
-                ret->object.type = tag_type;
+                ret->object.type = TYPE_TAG;
                 return ret;
         }
 	if (!obj->type)
-		obj->type = tag_type;
-        if (obj->type != tag_type) {
-                error("Object %s is a %s, not a tree", 
-                      sha1_to_hex(sha1), obj->type);
+		obj->type = TYPE_TAG;
+        if (obj->type != TYPE_TAG) {
+                error("Object %s is a %s, not a tree",
+                      sha1_to_hex(sha1), typename(obj->type));
                 return NULL;
         }
         return (struct tag *) obj;
diff --git a/tree.c b/tree.c
index 9bbe2da37b..64422fd27e 100644
--- a/tree.c
+++ b/tree.c
@@ -131,14 +131,14 @@ struct tree *lookup_tree(const unsigned char *sha1)
 	if (!obj) {
 		struct tree *ret = xcalloc(1, sizeof(struct tree));
 		created_object(sha1, &ret->object);
-		ret->object.type = tree_type;
+		ret->object.type = TYPE_TREE;
 		return ret;
 	}
 	if (!obj->type)
-		obj->type = tree_type;
-	if (obj->type != tree_type) {
-		error("Object %s is a %s, not a tree", 
-		      sha1_to_hex(sha1), obj->type);
+		obj->type = TYPE_TREE;
+	if (obj->type != TYPE_TREE) {
+		error("Object %s is a %s, not a tree",
+		      sha1_to_hex(sha1), typename(obj->type));
 		return NULL;
 	}
 	return (struct tree *) obj;
@@ -216,11 +216,11 @@ struct tree *parse_tree_indirect(const unsigned char *sha1)
 	do {
 		if (!obj)
 			return NULL;
-		if (obj->type == tree_type)
+		if (obj->type == TYPE_TREE)
 			return (struct tree *) obj;
-		else if (obj->type == commit_type)
+		else if (obj->type == TYPE_COMMIT)
 			obj = &(((struct commit *) obj)->tree->object);
-		else if (obj->type == tag_type)
+		else if (obj->type == TYPE_TAG)
 			obj = ((struct tag *) obj)->tagged;
 		else
 			return NULL;
diff --git a/upload-pack.c b/upload-pack.c
index 47560c9527..979e58306e 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -105,7 +105,7 @@ static int got_sha1(char *hex, unsigned char *sha1)
 			o = parse_object(sha1);
 		if (!o)
 			die("oops (%s)", sha1_to_hex(sha1));
-		if (o->type == commit_type) {
+		if (o->type == TYPE_COMMIT) {
 			struct commit_list *parents;
 			if (o->flags & THEY_HAVE)
 				return 0;
@@ -234,7 +234,7 @@ static int send_ref(const char *refname, const unsigned char *sha1)
 		o->flags |= OUR_REF;
 		nr_our_refs++;
 	}
-	if (o->type == tag_type) {
+	if (o->type == TYPE_TAG) {
 		o = deref_tag(o, refname, 0);
 		packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
 	}