Add comments and test for atomic load/store and mem2reg.

llvm-svn: 137690

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/test/Transforms/Mem2Reg/atomic.ll b/llvm/test/Transforms/Mem2Reg/atomic.ll
new file mode 100644
index 00000000000..982c41318b1
--- /dev/null
+++ b/llvm/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
+}