Add comments and test for atomic load/store and mem2reg.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137690 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/Mem2Reg/atomic.ll b/test/Transforms/Mem2Reg/atomic.ll
new file mode 100644
index 0000000..982c413
--- /dev/null
+++ b/test/Transforms/Mem2Reg/atomic.ll
@@ -0,0 +1,12 @@
+; RUN: opt -mem2reg < %s -S | FileCheck %s
+
+; mem2reg is allowed with arbitrary atomic operations (although we only support
+; it for atomic load and store at the moment).
+define i32 @test1(i32 %x) {
+; CHECK: @test1
+; CHECK: ret i32 %x
+ %a = alloca i32
+ store atomic i32 %x, i32* %a seq_cst, align 4
+ %r = load atomic i32* %a seq_cst, align 4
+ ret i32 %r
+}