t: add basic tests for our SHA-1 implementation

diff --git a/cache.h b/cache.h
index 2ead61f05a9b5fdf7e671b9d5530dfc64f3dfab9..85a8e7b10136afdf66e239bfbb5b60a52d44ef87 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -1024,16 +1024,12 @@ extern const struct object_id null_oid;
 static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
 {
        /*
-        * This is a temporary optimization hack. By asserting the size here,
-        * we let the compiler know that it's always going to be 20, which lets
-        * it turn this fixed-size memcmp into a few inline instructions.
-        *
-        * This will need to be extended or ripped out when we learn about
-        * hashes of different sizes.
+        * Teach the compiler that there are only two possibilities of hash size
+        * here, so that it can optimize for this case as much as possible.
         */
-       if (the_hash_algo->rawsz != 20)
-               BUG("hash size not yet supported by hashcmp");
-       return memcmp(sha1, sha2, the_hash_algo->rawsz);
+       if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)
+               return memcmp(sha1, sha2, GIT_MAX_RAWSZ);
+       return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
 }
 
 static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
@@ -1043,7 +1039,13 @@ static inline int oidcmp(const struct object_id *oid1, const struct object_id *o
 
 static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)
 {
-       return !hashcmp(sha1, sha2);
+       /*
+        * We write this here instead of deferring to hashcmp so that the
+        * compiler can properly inline it and avoid calling memcmp.
+        */
+       if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)
+               return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);
+       return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
 }
 
 static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)