@@ -494,6 +494,14 @@ fold_using_range::fold_stmt (vrange &r, gimple *s, fur_source &src, tree name)
else if (is_a<gassign *> (s) && gimple_assign_rhs_code (s) == COND_EXPR)
res = range_of_cond_expr (r, as_a<gassign *> (s), src);
+ // If the result is varying, check for basic nonnegativeness.
+ // Specifically this helps for now with strict enum in cases like
+ // g++.dg/warn/pr33738.C.
+ bool so_p;
+ if (res && r.varying_p () && INTEGRAL_TYPE_P (r.type ())
+ && gimple_stmt_nonnegative_warnv_p (s, &so_p))
+ r.set_nonnegative (r.type ());
+
if (!res)
{
// If no name specified or range is unsupported, bail.
When strict enums are in use, we don't always get ranges reduced sufficiently thru casts and such. Ranger vrp has been missing the odd case because I didn't notice that gimple_stmt_nonnegative_warnv_p() use to be called on all integral results that were varying, not just calls like it was doing. this corrects that. Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed. Andrew commit a87819b8f1b890d36a3f05bd9de80be20e9525dd Author: Andrew MacLeod <amacleod@redhat.com> Date: Tue Oct 25 15:16:47 2022 -0400 Check if varying may also be non-negative. When using strict enums, we can sometimes turn varying into a better range. * gimple-range-fold.cc (fold_using_range::fold_stmt): Check if stmt is non-negative and adjust the range.