Add codegen test for issue 138497

Author: jamie-osec

tests/codegen-llvm/issues/issue-138497-nonzero-remove-trailing-zeroes.rs

@@ -0,0 +1,17 @@
+//! This test checks that removing trailing zeroes from a `NonZero`,
+//! then creating a new `NonZero` from the result does not panic.
+
+//@ min-llvm-version: 21
+//@ compile-flags: -O -Zmerge-functions=disabled
+#![crate_type = "lib"]
+
+use std::num::NonZero;
+
+// CHECK-LABEL: @remove_trailing_zeros
+#[no_mangle]
+pub fn remove_trailing_zeros(x: NonZero<u8>) -> NonZero<u8> {
+    // CHECK-NOT: unwrap_failed
+    // CHECK-NOT: br
+    // CHECK ret i8
+    NonZero::new(x.get() >> x.trailing_zeros()).unwrap()
+}