1 files changed, 30 insertions, 0 deletions
diff --git a/src/test/codegen/c-variadic-opt.rs b/src/test/codegen/c-variadic-opt.rs
new file mode 100644
index 000000000..969dce80f
--- /dev/null
+++ b/src/test/codegen/c-variadic-opt.rs
@@ -0,0 +1,30 @@
+// compile-flags: -C opt-level=3
+
+#![crate_type = "lib"]
+#![feature(c_variadic)]
+#![no_std]
+use core::ffi::VaList;
+
+extern "C" {
+    fn vprintf(fmt: *const i8, ap: VaList) -> i32;
+}
+
+// Ensure that `va_start` and `va_end` are properly injected even
+// when the "spoofed" `VaListImpl` is not used.
+#[no_mangle]
+pub unsafe extern "C" fn c_variadic_no_use(fmt: *const i8, mut ap: ...) -> i32 {
+    // CHECK: call void @llvm.va_start
+    vprintf(fmt, ap.as_va_list())
+    // CHECK: call void @llvm.va_end
+}
+
+// Check that `VaListImpl::clone` gets inlined into a direct call to `llvm.va_copy`
+#[no_mangle]
+pub unsafe extern "C" fn c_variadic_clone(fmt: *const i8, mut ap: ...) -> i32 {
+    // CHECK: call void @llvm.va_start
+    let mut ap2 = ap.clone();
+    // CHECK: call void @llvm.va_copy
+    let res = vprintf(fmt, ap2.as_va_list());
+    res
+    // CHECK: call void @llvm.va_end
+}