Function ExecInitExprSlots

src/backend/executor/execExpr.c:2652–2663

* Add expression steps deforming the ExprState's inner/outer/scan slots * as much as required by the expression. */

 * as much as required by the expression.
 */
static void
ExecInitExprSlots(ExprState *state, Node *node)
{
	LastAttnumInfo info = {0, 0, 0};

	/*
	 * Figure out which attributes we're going to need.
	 */
	get_last_attnums_walker(node, &info);

	ExecPushExprSlots(state, &info);
}

/*
 * Add steps deforming the ExprState's inner/out/scan slots as much as