commit bbf688a84de7001d033764b848a50cbad42f3d5a
author Jorge Aparicio <jorge@japaric.io> Sat Jun 30 19:56:08 2018
committer Jorge Aparicio <jorge@japaric.io> Thu Jul 05 21:44:29 2018
tree 1a631bf9f7239612dcc09c72be1df3d749a39850
parent 94eb1760551096363ec04e42367b6b195592dbd8

enable Atomic*.{load,store} for ARMv6-M / MSP430

closes #45085

this commit adds an `atomic_cas` target option and an unstable `#[cfg(target_has_atomic_cas)]`
attribute to enable a subset of the `Atomic*` API on architectures that don't support atomic CAS
natively, like MSP430 and ARMv6-M.

src/librustc/session/config.rs

diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index f97e11e..93bfe1f 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1367,6 +1367,7 @@
     let vendor = &sess.target.target.target_vendor;
     let min_atomic_width = sess.target.target.min_atomic_width();
     let max_atomic_width = sess.target.target.max_atomic_width();
+    let atomic_cas = sess.target.target.options.atomic_cas;
 
     let mut ret = HashSet::new();
     // Target bindings.
@@ -1406,6 +1407,9 @@
             }
         }
     }
+    if atomic_cas {
+        ret.insert((Symbol::intern("target_has_atomic_cas"), None));
+    }
     if sess.opts.debug_assertions {
         ret.insert((Symbol::intern("debug_assertions"), None));
     }