Remove direct uses of ItemPointer.{ip_blkid,ip_posid}

There are no functional changes here; this simply encapsulates knowledge
of the ItemPointerData struct so that a future patch can change things
without more breakage.

All direct users of ip_blkid and ip_posid are changed to use existing
macros ItemPointerGetBlockNumber and ItemPointerGetOffsetNumber
respectively.  For callers where that's inappropriate (because they
Assert that the itempointer is is valid-looking), add
ItemPointerGetBlockNumberNoCheck and ItemPointerGetOffsetNumberNoCheck,
which lack the assertion but are otherwise identical.

Author: Pavan Deolasee
Discussion: https://postgr.es/m/CABOikdNnFon4cJiL=h1mZH3bgUeU+sWHuU4Yr8AB=j3A2p1GiA@mail.gmail.com

2 files changed, 22 insertions, 21 deletions

diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c
index 87cd9eaa9f5..610d386ff8a 100644
--- a/src/backend/access/gin/ginget.c
+++ b/src/backend/access/gin/ginget.c
@@ -626,8 +626,9 @@ entryLoadMoreItems(GinState *ginstate, GinScanEntry entry,
 		}
 		else
 		{
-			entry->btree.itemptr = advancePast;
-			entry->btree.itemptr.ip_posid++;
+			ItemPointerSet(&entry->btree.itemptr,
+						   GinItemPointerGetBlockNumber(&advancePast),
+			  OffsetNumberNext(GinItemPointerGetOffsetNumber(&advancePast)));
 		}
 		entry->btree.fullScan = false;
 		stack = ginFindLeafPage(&entry->btree, true, snapshot);
@@ -979,15 +980,17 @@ keyGetItem(GinState *ginstate, MemoryContext tempCtx, GinScanKey key,
 		if (GinItemPointerGetBlockNumber(&advancePast) <
 			GinItemPointerGetBlockNumber(&minItem))
 		{
-			advancePast.ip_blkid = minItem.ip_blkid;
-			advancePast.ip_posid = 0;
+			ItemPointerSet(&advancePast,
+						   GinItemPointerGetBlockNumber(&minItem),
+						   InvalidOffsetNumber);
 		}
 	}
 	else
 	{
-		Assert(minItem.ip_posid > 0);
-		advancePast = minItem;
-		advancePast.ip_posid--;
+		Assert(GinItemPointerGetOffsetNumber(&minItem) > 0);
+		ItemPointerSet(&advancePast,
+					   GinItemPointerGetBlockNumber(&minItem),
+				  OffsetNumberPrev(GinItemPointerGetOffsetNumber(&minItem)));
 	}
 
 	/*
@@ -1245,15 +1248,17 @@ scanGetItem(IndexScanDesc scan, ItemPointerData advancePast,
 				if (GinItemPointerGetBlockNumber(&advancePast) <
 					GinItemPointerGetBlockNumber(&key->curItem))
 				{
-					advancePast.ip_blkid = key->curItem.ip_blkid;
-					advancePast.ip_posid = 0;
+					ItemPointerSet(&advancePast,
+								 GinItemPointerGetBlockNumber(&key->curItem),
+								   InvalidOffsetNumber);
 				}
 			}
 			else
 			{
-				Assert(key->curItem.ip_posid > 0);
-				advancePast = key->curItem;
-				advancePast.ip_posid--;
+				Assert(GinItemPointerGetOffsetNumber(&key->curItem) > 0);
+				ItemPointerSet(&advancePast,
+							   GinItemPointerGetBlockNumber(&key->curItem),
+							   OffsetNumberPrev(GinItemPointerGetOffsetNumber(&key->curItem)));
 			}
 
 			/*
diff --git a/src/backend/access/gin/ginpostinglist.c b/src/backend/access/gin/ginpostinglist.c
index 598069d06ff..8d2d31ac723 100644
--- a/src/backend/access/gin/ginpostinglist.c
+++ b/src/backend/access/gin/ginpostinglist.c
@@ -79,13 +79,11 @@ itemptr_to_uint64(const ItemPointer iptr)
 	uint64		val;
 
 	Assert(ItemPointerIsValid(iptr));
-	Assert(iptr->ip_posid < (1 << MaxHeapTuplesPerPageBits));
+	Assert(GinItemPointerGetOffsetNumber(iptr) < (1 << MaxHeapTuplesPerPageBits));
 
-	val = iptr->ip_blkid.bi_hi;
-	val <<= 16;
-	val |= iptr->ip_blkid.bi_lo;
+	val = GinItemPointerGetBlockNumber(iptr);
 	val <<= MaxHeapTuplesPerPageBits;
-	val |= iptr->ip_posid;
+	val |= GinItemPointerGetOffsetNumber(iptr);
 
 	return val;
 }
@@ -93,11 +91,9 @@ itemptr_to_uint64(const ItemPointer iptr)
 static inline void
 uint64_to_itemptr(uint64 val, ItemPointer iptr)
 {
-	iptr->ip_posid = val & ((1 << MaxHeapTuplesPerPageBits) - 1);
+	GinItemPointerSetOffsetNumber(iptr, val & ((1 << MaxHeapTuplesPerPageBits) - 1));
 	val = val >> MaxHeapTuplesPerPageBits;
-	iptr->ip_blkid.bi_lo = val & 0xFFFF;
-	val = val >> 16;
-	iptr->ip_blkid.bi_hi = val & 0xFFFF;
+	GinItemPointerSetBlockNumber(iptr, val);
 
 	Assert(ItemPointerIsValid(iptr));
 }