common::type_is_fat_ptr(bcx.tcx(), ty));
} else if common::type_is_imm_pair(bcx.ccx(), ty) {
// We allow pairs and uses of any of their 2 fields.
+ } else if !analyzer.seen_assigned.contains(index) {
+ // No assignment has been seen, which means that
+ // either the local has been marked as lvalue
+ // already, or there is no possible initialization
+ // for the local, making any reads invalid.
+ // This is useful in weeding out dead temps.
} else {
// These sorts of types require an alloca. Note that
// type_is_immediate() may *still* be true, particularly
--- /dev/null
+// 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());
+}