add support for the `cold` function attribute

This allows a function to marked as infrequently called, resulting in
any branch calling it to be considered colder.

2 files changed, 3 insertions, 0 deletions

diff --git a/src/libstd/rt/borrowck.rs b/src/libstd/rt/borrowck.rs
index 9d13e79464a..7fcd674009d 100644
--- a/src/libstd/rt/borrowck.rs
+++ b/src/libstd/rt/borrowck.rs
@@ -57,6 +57,7 @@ pub fn clear_task_borrow_list() {
     let _ = try_take_task_borrow_list();
 }
 
+#[cold]
 unsafe fn fail_borrowed(box: *mut raw::Box<()>, file: *c_char, line: size_t) -> ! {
     debug_borrow("fail_borrowed: ", box, 0, 0, file, line);
 
diff --git a/src/libstd/unstable/lang.rs b/src/libstd/unstable/lang.rs
index 6dfb319d592..89126bf9c9c 100644
--- a/src/libstd/unstable/lang.rs
+++ b/src/libstd/unstable/lang.rs
@@ -16,11 +16,13 @@ use libc::{c_char, size_t, uintptr_t};
 use rt::task;
 use rt::borrowck;
 
+#[cold]
 #[lang="fail_"]
 pub fn fail_(expr: *c_char, file: *c_char, line: size_t) -> ! {
     task::begin_unwind(expr, file, line);
 }
 
+#[cold]
 #[lang="fail_bounds_check"]
 pub fn fail_bounds_check(file: *c_char, line: size_t, index: size_t, len: size_t) -> ! {
     let msg = format!("index out of bounds: the len is {} but the index is {}",