test(codegen): add looping_over_ne_bytes test for #133528

tests/codegen/issues/looping-over-ne-bytes-133528.rs

@@ -0,0 +1,17 @@
+//@ compile-flags: -Copt-level=3
+//@ min-llvm-version: 20
+#![crate_type = "lib"]
+
+/// Ensure the function is properly optimized
+/// In the issue #133528, the function was not getting optimized
+/// whereas, a version with `bytes` wrapped into a `black_box` was optimized
+/// It was probably a LLVM bug that was fixed in LLVM 20
+
+// CHECK-LABEL: @looping_over_ne_bytes
+// CHECK: icmp eq i64 %input, -1
+// CHECK-NEXT: ret i1
+#[no_mangle]
+fn looping_over_ne_bytes(input: u64) -> bool {
+    let bytes = input.to_ne_bytes();
+    bytes.iter().all(|x| *x == !0)
+}