auto merge of #8087 : Aatch/rust/atomics, r=huonw

Adds a fence operation to close #8061

Also adds static initializers to for atomic types. Since the fields are private, you aren't able to have `static mut` variables that are an atomic type. Each atomic type's initializer starts at a 0-value (so unset for `AtomicFlag` and false for `AtomicBool`).

1 files changed, 4 insertions, 1 deletions

diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 2a1f26bf441..beaa7e1daef 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -513,6 +513,9 @@ extern "C" LLVMValueRef LLVMBuildAtomicCmpXchg(LLVMBuilderRef B,
     return wrap(unwrap(B)->CreateAtomicCmpXchg(unwrap(target), unwrap(old),
                                                unwrap(source), order));
 }
+extern "C" LLVMValueRef LLVMBuildAtomicFence(LLVMBuilderRef B, AtomicOrdering order) {
+    return wrap(unwrap(B)->CreateFence(order));
+}
 extern "C" LLVMValueRef LLVMBuildAtomicRMW(LLVMBuilderRef B,
                                            AtomicRMWInst::BinOp op,
                                            LLVMValueRef target,
@@ -838,4 +841,4 @@ extern "C" LLVMValueRef LLVMDIBuilderCreateUnionType(
         Flags,
         unwrapDI<DIArray>(Elements),
         RunTimeLang));
-}
\ No newline at end of file
+}