Deduplicate code between slot_getallattrs() and slot_getsomeattrs().

Code in slot_getallattrs() is the same as if slot_getsomeattrs() is
called with number of attributes specified in the tuple
descriptor. Implement it that way instead of duplicating the code
between those two functions.

This is part of a patchseries abstracting TupleTableSlots so they can
store arbitrary forms of tuples, but is a nice enough cleanup on its
own.

Author: Ashutosh Bapat
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/20180220224318.gw4oe5jadhpmcdnm@alap3.anarazel.de

src/backend/access/common/heaptuple.c

@@ -1601,51 +1601,6 @@ slot_getattr(TupleTableSlot *slot, int attnum, bool *isnull)
 	return slot->tts_values[attnum - 1];
 }
 
-/*
- * slot_getallattrs
- *		This function forces all the entries of the slot's Datum/isnull
- *		arrays to be valid.  The caller may then extract data directly
- *		from those arrays instead of using slot_getattr.
- */
-void
-slot_getallattrs(TupleTableSlot *slot)
-{
-	int			tdesc_natts = slot->tts_tupleDescriptor->natts;
-	int			attnum;
-	HeapTuple	tuple;
-
-	/* Quick out if we have 'em all already */
-	if (slot->tts_nvalid == tdesc_natts)
-		return;
-
-	/*
-	 * otherwise we had better have a physical tuple (tts_nvalid should equal
-	 * natts in all virtual-tuple cases)
-	 */
-	tuple = slot->tts_tuple;
-	if (tuple == NULL)			/* internal error */
-		elog(ERROR, "cannot extract attribute from empty tuple slot");
-
-	/*
-	 * load up any slots available from physical tuple
-	 */
-	attnum = HeapTupleHeaderGetNatts(tuple->t_data);
-	attnum = Min(attnum, tdesc_natts);
-
-	slot_deform_tuple(slot, attnum);
-
-	attnum = slot->tts_nvalid;
-
-	/*
-	 * If tuple doesn't have all the atts indicated by tupleDesc, read the
-	 * rest as NULLS or missing values.
-	 */
-	if (attnum < tdesc_natts)
-		slot_getmissingattrs(slot, attnum, tdesc_natts);
-
-	slot->tts_nvalid = tdesc_natts;
-}
-
 /*
  * slot_getsomeattrs
  *		This function forces the entries of the slot's Datum/isnull

src/include/executor/tuptable.h

@@ -174,11 +174,22 @@ extern TupleTableSlot *ExecCopySlot(TupleTableSlot *dstslot,
 
 /* in access/common/heaptuple.c */
 extern Datum slot_getattr(TupleTableSlot *slot, int attnum, bool *isnull);
-extern void slot_getallattrs(TupleTableSlot *slot);
 extern void slot_getsomeattrs(TupleTableSlot *slot, int attnum);
 extern bool slot_attisnull(TupleTableSlot *slot, int attnum);
 extern bool slot_getsysattr(TupleTableSlot *slot, int attnum,
 				Datum *value, bool *isnull);
 extern void slot_getmissingattrs(TupleTableSlot *slot, int startAttNum, int lastAttNum);
 
+/*
+ * slot_getallattrs
+ *		This function forces all the entries of the slot's Datum/isnull
+ *		arrays to be valid.  The caller may then extract data directly
+ *		from those arrays instead of using slot_getattr.
+ */
+static inline void
+slot_getallattrs(TupleTableSlot *slot)
+{
+	slot_getsomeattrs(slot, slot->tts_tupleDescriptor->natts);
+}
+
 #endif							/* TUPTABLE_H */