Inline TransactionIdFollows/Precedes[OrEquals]()

These functions appeared prominently in a profile of a patch that sets
the visibility map on-access. Inline them to remove call overhead and
make them cheaper to use in hot paths.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/2wk7jo4m4qwh5sn33pfgerdjfujebbccsmmlownybddbh6nawl%40mdyyqpqzxjek

src/backend/access/transam/transam.c

@@ -273,70 +273,6 @@ TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids)
 							   TRANSACTION_STATUS_ABORTED, InvalidXLogRecPtr);
 }
 
-/*
- * TransactionIdPrecedes --- is id1 logically < id2?
- */
-bool
-TransactionIdPrecedes(TransactionId id1, TransactionId id2)
-{
-	/*
-	 * If either ID is a permanent XID then we can just do unsigned
-	 * comparison.  If both are normal, do a modulo-2^32 comparison.
-	 */
-	int32		diff;
-
-	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
-		return (id1 < id2);
-
-	diff = (int32) (id1 - id2);
-	return (diff < 0);
-}
-
-/*
- * TransactionIdPrecedesOrEquals --- is id1 logically <= id2?
- */
-bool
-TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2)
-{
-	int32		diff;
-
-	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
-		return (id1 <= id2);
-
-	diff = (int32) (id1 - id2);
-	return (diff <= 0);
-}
-
-/*
- * TransactionIdFollows --- is id1 logically > id2?
- */
-bool
-TransactionIdFollows(TransactionId id1, TransactionId id2)
-{
-	int32		diff;
-
-	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
-		return (id1 > id2);
-
-	diff = (int32) (id1 - id2);
-	return (diff > 0);
-}
-
-/*
- * TransactionIdFollowsOrEquals --- is id1 logically >= id2?
- */
-bool
-TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2)
-{
-	int32		diff;
-
-	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
-		return (id1 >= id2);
-
-	diff = (int32) (id1 - id2);
-	return (diff >= 0);
-}
-
 
 /*
  * TransactionIdLatest --- get latest XID among a main xact and its children

src/include/access/transam.h

@@ -255,6 +255,72 @@ typedef struct TransamVariablesData
 } TransamVariablesData;
 
 
+
+/*
+ * TransactionIdPrecedes --- is id1 logically < id2?
+ */
+static inline bool
+TransactionIdPrecedes(TransactionId id1, TransactionId id2)
+{
+	/*
+	 * If either ID is a permanent XID then we can just do unsigned
+	 * comparison.  If both are normal, do a modulo-2^32 comparison.
+	 */
+	int32		diff;
+
+	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
+		return (id1 < id2);
+
+	diff = (int32) (id1 - id2);
+	return (diff < 0);
+}
+
+/*
+ * TransactionIdPrecedesOrEquals --- is id1 logically <= id2?
+ */
+static inline bool
+TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2)
+{
+	int32		diff;
+
+	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
+		return (id1 <= id2);
+
+	diff = (int32) (id1 - id2);
+	return (diff <= 0);
+}
+
+/*
+ * TransactionIdFollows --- is id1 logically > id2?
+ */
+static inline bool
+TransactionIdFollows(TransactionId id1, TransactionId id2)
+{
+	int32		diff;
+
+	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
+		return (id1 > id2);
+
+	diff = (int32) (id1 - id2);
+	return (diff > 0);
+}
+
+/*
+ * TransactionIdFollowsOrEquals --- is id1 logically >= id2?
+ */
+static inline bool
+TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2)
+{
+	int32		diff;
+
+	if (!TransactionIdIsNormal(id1) || !TransactionIdIsNormal(id2))
+		return (id1 >= id2);
+
+	diff = (int32) (id1 - id2);
+	return (diff >= 0);
+}
+
+
 /* ----------------
  *		extern declarations
  * ----------------
@@ -274,10 +340,6 @@ extern bool TransactionIdDidAbort(TransactionId transactionId);
 extern void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids);
 extern void TransactionIdAsyncCommitTree(TransactionId xid, int nxids, TransactionId *xids, XLogRecPtr lsn);
 extern void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids);
-extern bool TransactionIdPrecedes(TransactionId id1, TransactionId id2);
-extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2);
-extern bool TransactionIdFollows(TransactionId id1, TransactionId id2);
-extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2);
 extern TransactionId TransactionIdLatest(TransactionId mainxid,
 										 int nxids, const TransactionId *xids);
 extern XLogRecPtr TransactionIdGetCommitLSN(TransactionId xid);