1 files changed, 23 insertions, 0 deletions
diff --git a/src/test/ui/codegen/init-large-type.rs b/src/test/ui/codegen/init-large-type.rs
new file mode 100644
index 000000000..ce905572f
--- /dev/null
+++ b/src/test/ui/codegen/init-large-type.rs
@@ -0,0 +1,23 @@
+// compile-flags: -O
+// run-pass
+
+#![allow(unused_must_use)]
+// Makes sure that zero-initializing large types is reasonably fast,
+// Doing it incorrectly causes massive slowdown in LLVM during
+// optimisation.
+
+// pretty-expanded FIXME #23616
+// ignore-emscripten no threads support
+
+#![feature(intrinsics)]
+
+use std::{mem, thread};
+
+const SIZE: usize = 1024 * 1024;
+
+fn main() {
+    // do the test in a new thread to avoid (spurious?) stack overflows
+    thread::spawn(|| {
+        let _memory: [u8; SIZE] = unsafe { mem::zeroed() };
+    }).join();
+}