Get rid of our dependency on type "long" for memory size calculations.

Consistently use "Size" (or size_t, or in some places int64 or double)
as the type for variables holding memory allocation sizes.  In most
places variables' data types were fine already, but we had an ancient
habit of computing bytes from kilobytes-units GUCs with code like
"work_mem * 1024L".  That risks overflow on Win64 where they did not
make "long" as wide as "size_t".  We worked around that by restricting
such GUCs' ranges, so you couldn't set work_mem et al higher than 2GB
on Win64.  This patch removes that restriction, after replacing such
calculations with "work_mem * (Size) 1024" or variants of that.

It should be noted that this patch was constructed by searching
outwards from the GUCs that have MAX_KILOBYTES as upper limit.
So I can't positively guarantee there are no other places doing
memory-size arithmetic in int or long variables.  I do however feel
pretty confident that increasing MAX_KILOBYTES on Win64 is safe now.
Also, nothing in our code should be dealing in multiple-gigabyte
allocations without authorization from a relevant GUC, so it seems
pretty likely that this search caught everything that could be at
risk of overflow.

Author: Vladlen Popolitov <v.popolitov@postgrespro.ru>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/1a01f0-66ec2d80-3b-68487680@27595217

src/backend/access/gin/ginfast.c

@@ -39,7 +39,7 @@
 int			gin_pending_list_limit = 0;
 
 #define GIN_PAGE_FREESIZE \
-	( BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - MAXALIGN(sizeof(GinPageOpaqueData)) )
+	( (Size) BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - MAXALIGN(sizeof(GinPageOpaqueData)) )
 
 typedef struct KeyArray
 {
@@ -456,7 +456,7 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
 	 * ginInsertCleanup() should not be called inside our CRIT_SECTION.
 	 */
 	cleanupSize = GinGetPendingListCleanupSize(index);
-	if (metadata->nPendingPages * GIN_PAGE_FREESIZE > cleanupSize * 1024L)
+	if (metadata->nPendingPages * GIN_PAGE_FREESIZE > cleanupSize * (Size) 1024)
 		needCleanup = true;
 
 	UnlockReleaseBuffer(metabuffer);
@@ -795,7 +795,7 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 				blknoFinish;
 	bool		cleanupFinish = false;
 	bool		fsm_vac = false;
-	Size		workMemory;
+	int			workMemory;
 
 	/*
 	 * We would like to prevent concurrent cleanup process. For that we will
@@ -901,7 +901,7 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 		 */
 		if (GinPageGetOpaque(page)->rightlink == InvalidBlockNumber ||
 			(GinPageHasFullRow(page) &&
-			 (accum.allocatedMemory >= workMemory * 1024L)))
+			 accum.allocatedMemory >= workMemory * (Size) 1024))
 		{
 			ItemPointerData *list;
 			uint32		nlist;

src/backend/access/gin/ginget.c

@@ -125,7 +125,7 @@ collectMatchBitmap(GinBtreeData *btree, GinBtreeStack *stack,
 	CompactAttribute *attr;
 
 	/* Initialize empty bitmap result */
-	scanEntry->matchBitmap = tbm_create(work_mem * 1024L, NULL);
+	scanEntry->matchBitmap = tbm_create(work_mem * (Size) 1024, NULL);
 
 	/* Null query cannot partial-match anything */
 	if (scanEntry->isPartialMatch &&

src/backend/access/gin/gininsert.c

@@ -288,7 +288,7 @@ ginBuildCallback(Relation index, ItemPointer tid, Datum *values,
 							   values[i], isnull[i], tid);
 
 	/* If we've maxed out our available memory, dump everything to the index */
-	if (buildstate->accum.allocatedMemory >= (Size) maintenance_work_mem * 1024L)
+	if (buildstate->accum.allocatedMemory >= maintenance_work_mem * (Size) 1024)
 	{
 		ItemPointerData *list;
 		Datum		key;

src/backend/access/hash/hash.c

@@ -120,7 +120,7 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	double		reltuples;
 	double		allvisfrac;
 	uint32		num_buckets;
-	long		sort_threshold;
+	Size		sort_threshold;
 	HashBuildState buildstate;
 
 	/*
@@ -155,13 +155,13 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	 * one page.  Also, "initial index size" accounting does not include the
 	 * metapage, nor the first bitmap page.
 	 */
-	sort_threshold = (maintenance_work_mem * 1024L) / BLCKSZ;
+	sort_threshold = (maintenance_work_mem * (Size) 1024) / BLCKSZ;
 	if (index->rd_rel->relpersistence != RELPERSISTENCE_TEMP)
 		sort_threshold = Min(sort_threshold, NBuffers);
 	else
 		sort_threshold = Min(sort_threshold, NLocBuffer);
 
-	if (num_buckets >= (uint32) sort_threshold)
+	if (num_buckets >= sort_threshold)
 		buildstate.spool = _h_spoolinit(heap, index, num_buckets);
 	else
 		buildstate.spool = NULL;

src/backend/access/heap/vacuumlazy.c

@@ -2070,7 +2070,7 @@ lazy_vacuum(LVRelState *vacrel)
 		 */
 		threshold = (double) vacrel->rel_pages * BYPASS_THRESHOLD_PAGES;
 		bypass = (vacrel->lpdead_item_pages < threshold &&
-				  (TidStoreMemoryUsage(vacrel->dead_items) < (32L * 1024L * 1024L)));
+				  TidStoreMemoryUsage(vacrel->dead_items) < 32 * 1024 * 1024);
 	}
 
 	if (bypass)
@@ -3037,7 +3037,7 @@ dead_items_alloc(LVRelState *vacrel, int nworkers)
 	 */
 
 	dead_items_info = (VacDeadItemsInfo *) palloc(sizeof(VacDeadItemsInfo));
-	dead_items_info->max_bytes = vac_work_mem * 1024L;
+	dead_items_info->max_bytes = vac_work_mem * (Size) 1024;
 	dead_items_info->num_items = 0;
 	vacrel->dead_items_info = dead_items_info;
 

src/backend/access/nbtree/nbtpage.c

@@ -2953,7 +2953,7 @@ _bt_lock_subtree_parent(Relation rel, Relation heaprel, BlockNumber child,
 void
 _bt_pendingfsm_init(Relation rel, BTVacState *vstate, bool cleanuponly)
 {
-	int64		maxbufsize;
+	Size		maxbufsize;
 
 	/*
 	 * Don't bother with optimization in cleanup-only case -- we don't expect
@@ -2969,12 +2969,13 @@ _bt_pendingfsm_init(Relation rel, BTVacState *vstate, bool cleanuponly)
 	 * int overflow here.
 	 */
 	vstate->bufsize = 256;
-	maxbufsize = (work_mem * 1024L) / sizeof(BTPendingFSM);
-	maxbufsize = Min(maxbufsize, INT_MAX);
+	maxbufsize = (work_mem * (Size) 1024) / sizeof(BTPendingFSM);
 	maxbufsize = Min(maxbufsize, MaxAllocSize / sizeof(BTPendingFSM));
+	/* BTVacState.maxbufsize has type int */
+	maxbufsize = Min(maxbufsize, INT_MAX);
 	/* Stay sane with small work_mem */
 	maxbufsize = Max(maxbufsize, vstate->bufsize);
-	vstate->maxbufsize = maxbufsize;
+	vstate->maxbufsize = (int) maxbufsize;
 
 	/* Allocate buffer, indicate that there are currently 0 pending pages */
 	vstate->pendingpages = palloc(sizeof(BTPendingFSM) * vstate->bufsize);