rustc_trans: do not generate allocas for unused locals.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/test/run-pass/mir_heavy_promoted.rs b/src/test/run-pass/mir_heavy_promoted.rs
new file mode 100644
index 00000000000..9e033421574
--- /dev/null
+++ b/src/test/run-pass/mir_heavy_promoted.rs
@@ -0,0 +1,18 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+const TEST_DATA: [u8; 32 * 1024 * 1024] = [42; 32 * 1024 * 1024];
+
+// Check that the promoted copy of TEST_DATA doesn't
+// leave an alloca from an unused temp behind, which,
+// without optimizations, can still blow the stack.
+fn main() {
+    println!("{}", TEST_DATA.len());
+}