+ * expression is constructed. Using this map to construct the call
+ * expression usually yields simpler results.
+ * Because we perform the single-valuedness test on the gisted map,
+ * we may in rare cases fail to recognize that the inverse schedule
+ * is single-valued. This becomes problematic if this happens
+ * from the recursive call through generate_non_single_valued
+ * as we would then end up in an infinite recursion.
+ * We therefore check if we are inside a call to generate_non_single_valued
+ * and revert to the ungisted map if the gisted map turns out not to be
+ * single-valued.