diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index ce8a7f1d666..b3690d8935e 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -964,7 +964,7 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 		/* an aggregate could return non-null with null input */
 		return true;
 	}
-	if (IsA(node, GroupingFunc))
+	else if (IsA(node, GroupingFunc))
 	{
 		/*
 		 * A GroupingFunc doesn't evaluate its arguments, and therefore must
@@ -972,12 +972,12 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 		 */
 		return true;
 	}
-	if (IsA(node, WindowFunc))
+	else if (IsA(node, WindowFunc))
 	{
 		/* a window function could return non-null with null input */
 		return true;
 	}
-	if (IsA(node, SubscriptingRef))
+	else if (IsA(node, SubscriptingRef))
 	{
 		SubscriptingRef *sbsref = (SubscriptingRef *) node;
 		const SubscriptRoutines *sbsroutines;
@@ -991,17 +991,25 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 			return true;
 		/* else fall through to check args */
 	}
-	if (IsA(node, DistinctExpr))
+	else if (IsA(node, DistinctExpr))
 	{
 		/* IS DISTINCT FROM is inherently non-strict */
 		return true;
 	}
-	if (IsA(node, NullIfExpr))
+	else if (IsA(node, NullIfExpr))
 	{
 		/* NULLIF is inherently non-strict */
 		return true;
 	}
-	if (IsA(node, BoolExpr))
+	else if (IsA(node, ScalarArrayOpExpr))
+	{
+		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
+
+		if (!is_strict_saop(expr, false))
+			return true;
+		/* else fall through to check args */
+	}
+	else if (IsA(node, BoolExpr))
 	{
 		BoolExpr   *expr = (BoolExpr *) node;
 
@@ -1015,28 +1023,26 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 				break;
 		}
 	}
-	if (IsA(node, SubLink))
+	else if (IsA(node, SubLink))
 	{
 		/* In some cases a sublink might be strict, but in general not */
 		return true;
 	}
-	if (IsA(node, SubPlan))
+	else if (IsA(node, SubPlan))
 		return true;
-	if (IsA(node, AlternativeSubPlan))
+	else if (IsA(node, AlternativeSubPlan))
 		return true;
-	if (IsA(node, FieldStore))
+	else if (IsA(node, FieldStore))
 		return true;
-	if (IsA(node, CoerceViaIO))
+	else if (IsA(node, CoerceViaIO))
 	{
 		/*
 		 * CoerceViaIO is strict regardless of whether the I/O functions are,
-		 * so just go look at its argument; asking check_functions_in_node is
-		 * useless expense and could deliver the wrong answer.
+		 * so we should skip check_functions_in_node() and just fall through
+		 * to check the arguments.
 		 */
-		return contain_nonstrict_functions_walker((Node *) ((CoerceViaIO *) node)->arg,
-												  context);
 	}
-	if (IsA(node, ArrayCoerceExpr))
+	else if (IsA(node, ArrayCoerceExpr))
 	{
 		/*
 		 * ArrayCoerceExpr is strict at the array level, regardless of what
@@ -1046,29 +1052,31 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 		return contain_nonstrict_functions_walker((Node *) ((ArrayCoerceExpr *) node)->arg,
 												  context);
 	}
-	if (IsA(node, CaseExpr))
+	else if (IsA(node, CaseExpr))
 		return true;
-	if (IsA(node, ArrayExpr))
+	else if (IsA(node, ArrayExpr))
 		return true;
-	if (IsA(node, RowExpr))
+	else if (IsA(node, RowExpr))
 		return true;
-	if (IsA(node, RowCompareExpr))
+	else if (IsA(node, RowCompareExpr))
 		return true;
-	if (IsA(node, CoalesceExpr))
+	else if (IsA(node, CoalesceExpr))
 		return true;
-	if (IsA(node, MinMaxExpr))
+	else if (IsA(node, MinMaxExpr))
 		return true;
-	if (IsA(node, XmlExpr))
+	else if (IsA(node, XmlExpr))
 		return true;
-	if (IsA(node, NullTest))
+	else if (IsA(node, NullTest))
 		return true;
-	if (IsA(node, BooleanTest))
-		return true;
-
-	/* Check other function-containing nodes */
-	if (check_functions_in_node(node, contain_nonstrict_functions_checker,
-								context))
+	else if (IsA(node, BooleanTest))
 		return true;
+	else
+	{
+		/* Check other function-containing nodes */
+		if (check_functions_in_node(node, contain_nonstrict_functions_checker,
+									context))
+			return true;
+	}
 
 	return expression_tree_walker(node, contain_nonstrict_functions_walker,
 								  context);
@@ -1463,7 +1471,7 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
 	{
 		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
 
-		if (is_strict_saop(expr, true))
+		if (is_strict_saop(expr, top_level))
 			result = find_nonnullable_rels_walker((Node *) expr->args, false);
 	}
 	else if (IsA(node, BoolExpr))
@@ -1688,7 +1696,7 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 	{
 		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
 
-		if (is_strict_saop(expr, true))
+		if (is_strict_saop(expr, top_level))
 			result = find_nonnullable_vars_walker((Node *) expr->args, false);
 	}
 	else if (IsA(node, BoolExpr))