Move bitmap_hash and bitmap_match to bitmapset.c.

The closely-related function bms_hash_value is already defined in that
file, and this change means that hashfn.c no longer needs to depend on
nodes/bitmapset.h. That gets us closer to allowing use of the hash
functions in hashfn.c in frontend code.

Patch by me, reviewed by Suraj Kharage and Mark Dilger.

Discussion: http://postgr.es/m/CA+TgmoaRiG4TXND8QuM6JXFRkM_1wL2ZNhzaUKsuec9-4yrkgw@mail.gmail.com

src/backend/nodes/bitmapset.c

@@ -1167,3 +1167,26 @@ bms_hash_value(const Bitmapset *a)
 	return DatumGetUInt32(hash_any((const unsigned char *) a->words,
 								   (lastword + 1) * sizeof(bitmapword)));
 }
+
+/*
+ * bitmap_hash - hash function for keys that are (pointers to) Bitmapsets
+ *
+ * Note: don't forget to specify bitmap_match as the match function!
+ */
+uint32
+bitmap_hash(const void *key, Size keysize)
+{
+	Assert(keysize == sizeof(Bitmapset *));
+	return bms_hash_value(*((const Bitmapset *const *) key));
+}
+
+/*
+ * bitmap_match - match function to use with bitmap_hash
+ */
+int
+bitmap_match(const void *key1, const void *key2, Size keysize)
+{
+	Assert(keysize == sizeof(Bitmapset *));
+	return !bms_equal(*((const Bitmapset *const *) key1),
+					  *((const Bitmapset *const *) key2));
+}

src/backend/utils/hash/hashfn.c

@@ -23,7 +23,6 @@
 #include "postgres.h"
 
 #include "fmgr.h"
-#include "nodes/bitmapset.h"
 #include "utils/hashutils.h"
 #include "utils/hsearch.h"
 
@@ -695,26 +694,3 @@ uint32_hash(const void *key, Size keysize)
 	Assert(keysize == sizeof(uint32));
 	return DatumGetUInt32(hash_uint32(*((const uint32 *) key)));
 }
-
-/*
- * bitmap_hash: hash function for keys that are (pointers to) Bitmapsets
- *
- * Note: don't forget to specify bitmap_match as the match function!
- */
-uint32
-bitmap_hash(const void *key, Size keysize)
-{
-	Assert(keysize == sizeof(Bitmapset *));
-	return bms_hash_value(*((const Bitmapset *const *) key));
-}
-
-/*
- * bitmap_match: match function to use with bitmap_hash
- */
-int
-bitmap_match(const void *key1, const void *key2, Size keysize)
-{
-	Assert(keysize == sizeof(Bitmapset *));
-	return !bms_equal(*((const Bitmapset *const *) key1),
-					  *((const Bitmapset *const *) key2));
-}

src/include/nodes/bitmapset.h

@@ -116,5 +116,7 @@ extern int	bms_prev_member(const Bitmapset *a, int prevbit);
 
 /* support for hashtables using Bitmapsets as keys: */
 extern uint32 bms_hash_value(const Bitmapset *a);
+extern uint32 bitmap_hash(const void *key, Size keysize);
+extern int	bitmap_match(const void *key1, const void *key2, Size keysize);
 
 #endif							/* BITMAPSET_H */

src/include/utils/hsearch.h

@@ -152,8 +152,6 @@ extern void AtEOSubXact_HashTables(bool isCommit, int nestDepth);
 extern uint32 string_hash(const void *key, Size keysize);
 extern uint32 tag_hash(const void *key, Size keysize);
 extern uint32 uint32_hash(const void *key, Size keysize);
-extern uint32 bitmap_hash(const void *key, Size keysize);
-extern int	bitmap_match(const void *key1, const void *key2, Size keysize);
 
 #define oid_hash uint32_hash	/* Remove me eventually */