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>

1 files changed, 11 insertions, 11 deletions

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);
 		}