Remove rudiments of supporting procnum == 0 from 911e7020

Early versions of opclass options patch uses zero support procedure as opclass
options procedure.  This commit removes rudiments of it, which were committed
in 911e7020.  Also, it implements correct handling of amoptsprocnum == 0.

src/backend/access/index/indexam.c

@@ -773,9 +773,9 @@ index_getprocid(Relation irel,
 
 	nproc = irel->rd_indam->amsupport;
 
-	Assert(procnum >= 0 && procnum <= (uint16) nproc);
+	Assert(procnum > 0 && procnum <= (uint16) nproc);
 
-	procindex = ((nproc + 1) * (attnum - 1)) + procnum;
+	procindex = (nproc * (attnum - 1)) + (procnum - 1);
 
 	loc = irel->rd_support;
 
@@ -809,9 +809,9 @@ index_getprocinfo(Relation irel,
 	nproc = irel->rd_indam->amsupport;
 	optsproc = irel->rd_indam->amoptsprocnum;
 
-	Assert(procnum >= 0 && procnum <= (uint16) nproc);
+	Assert(procnum > 0 && procnum <= (uint16) nproc);
 
-	procindex = ((nproc + 1) * (attnum - 1)) + procnum;
+	procindex = (nproc * (attnum - 1)) + (procnum - 1);
 
 	locinfo = irel->rd_supportinfo;
 
@@ -937,10 +937,14 @@ index_opclass_options(Relation indrel, AttrNumber attnum, Datum attoptions,
 					  bool validate)
 {
 	int			amoptsprocnum = indrel->rd_indam->amoptsprocnum;
-	Oid			procid = index_getprocid(indrel, attnum, amoptsprocnum);
+	Oid			procid = InvalidOid;
 	FmgrInfo   *procinfo;
 	local_relopts relopts;
 
+	/* fetch options support procedure if specified */
+	if (amoptsprocnum != 0)
+		procid =index_getprocid(indrel, attnum, amoptsprocnum);
+
 	if (!OidIsValid(procid))
 	{
 		Oid			opclass;

src/backend/utils/cache/relcache.c

@@ -1426,7 +1426,7 @@ RelationInitIndexAccessInfo(Relation relation)
 	amsupport = relation->rd_indam->amsupport;
 	if (amsupport > 0)
 	{
-		int			nsupport = indnatts * (amsupport + 1);
+		int			nsupport = indnatts * amsupport;
 
 		relation->rd_support = (RegProcedure *)
 			MemoryContextAllocZero(indexcxt, nsupport * sizeof(RegProcedure));
@@ -1541,9 +1541,9 @@ IndexSupportInitialize(oidvector *indclass,
 		opFamily[attIndex] = opcentry->opcfamily;
 		opcInType[attIndex] = opcentry->opcintype;
 		if (maxSupportNumber > 0)
-			memcpy(&indexSupport[attIndex * (maxSupportNumber + 1)],
+			memcpy(&indexSupport[attIndex * maxSupportNumber],
 				   opcentry->supportProcs,
-				   (maxSupportNumber + 1) * sizeof(RegProcedure));
+				   maxSupportNumber * sizeof(RegProcedure));
 	}
 }
 
@@ -1695,12 +1695,13 @@ LookupOpclassInfo(Oid operatorClassOid,
 		{
 			Form_pg_amproc amprocform = (Form_pg_amproc) GETSTRUCT(htup);
 
-			if (amprocform->amprocnum < 0 ||
+			if (amprocform->amprocnum <= 0 ||
 				(StrategyNumber) amprocform->amprocnum > numSupport)
 				elog(ERROR, "invalid amproc number %d for opclass %u",
 					 amprocform->amprocnum, operatorClassOid);
 
-			opcentry->supportProcs[amprocform->amprocnum] = amprocform->amproc;
+			opcentry->supportProcs[amprocform->amprocnum - 1] =
+				amprocform->amproc;
 		}
 
 		systable_endscan(scan);
@@ -5201,6 +5202,9 @@ RelationGetIndexRawAttOptions(Relation indexrel)
 
 	for (attnum = 1; attnum <= natts; attnum++)
 	{
+		if (indexrel->rd_indam->amoptsprocnum == 0)
+			continue;
+
 		if (!OidIsValid(index_getprocid(indexrel, attnum,
 										indexrel->rd_indam->amoptsprocnum)))
 			continue;
@@ -5661,7 +5665,7 @@ load_relcache_init_file(bool shared)
 			}
 
 			/* set up zeroed fmgr-info vector */
-			nsupport = relform->relnatts * (rel->rd_indam->amsupport + 1);
+			nsupport = relform->relnatts * rel->rd_indam->amsupport;
 			rel->rd_supportinfo = (FmgrInfo *)
 				MemoryContextAllocZero(indexcxt, nsupport * sizeof(FmgrInfo));
 		}
@@ -5962,7 +5966,7 @@ write_relcache_init_file(bool shared)
 
 			/* next, write the vector of support procedure OIDs */
 			write_item(rel->rd_support,
-					   relform->relnatts * ((rel->rd_indam->amsupport + 1) * sizeof(RegProcedure)),
+					   relform->relnatts * (rel->rd_indam->amsupport * sizeof(RegProcedure)),
 					   fp);
 
 			/* next, write the vector of collation OIDs */