Test that NRVO elides the call to `memcpy`

1 files changed, 17 insertions, 0 deletions

diff --git a/src/test/codegen/nrvo.rs b/src/test/codegen/nrvo.rs
new file mode 100644
index 00000000000..fddb0d1fb3c
--- /dev/null
+++ b/src/test/codegen/nrvo.rs
@@ -0,0 +1,17 @@
+// compile-flags: -O
+
+#![crate_type = "lib"]
+
+// Ensure that we do not call `memcpy` for the following function.
+// `memset` and `init` should be called directly on the return pointer.
+#[no_mangle]
+pub fn nrvo(init: fn(&mut [u8; 4096])) -> [u8; 4096] {
+    // CHECK-LABEL: nrvo
+    // CHECK: @llvm.memset
+    // CHECK-NOT: @llvm.memcpy
+    // CHECK: ret
+    // CHECK-EMPTY
+    let mut buf = [0; 4096];
+    init(&mut buf);
+    buf
+}