diff_filespec: use only 2 bits for is_binary flag

The is_binary flag needs only three values: -1, 0, and 1.
However, we use a whole 32-bit int for it on most systems
(both 32- and 64- bit).

Instead, we can mark it to use only 2 bits. On 32-bit
systems, this lets it end up as part of the bitfield above
(saving 4 bytes). On 64-bit systems, we don't see any change
(because the savings end up as padding), but it does leave
room for another "free" 32-bit value to be added later.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diffcore.h b/diffcore.h
index d911bf0a42eeef68023459d6b03a8d1cafa74683..79de8cf28dc6919f069ae44f7f036a46264452e9 100644 (file)
--- a/diffcore.h
+++ b/diffcore.h
@@ -46,7 +46,7 @@ struct diff_filespec {
        unsigned is_stdin : 1;
        unsigned has_more_entries : 1; /* only appear in combined diff */
        /* data should be considered "binary"; -1 means "don't know yet" */
-       int is_binary;
+       int is_binary : 2;
        struct userdiff_driver *driver;
 };