add a codegen-llvm test for ManuallyDrop

Author: WaffleLapkin

tests/codegen-llvm/manually_drop_refs.rs

@@ -0,0 +1,43 @@
+// This test checks for absence of noalias and dereferenceable attributes on
+// arguments wrapped in `ManuallyDrop`.
+//
+//@ compile-flags: -Copt-level=3 -Zmerge-functions=disabled
+#![crate_type = "lib"]
+
+use std::mem::ManuallyDrop;
+
+// CHECK: define {{(dso_local )?}}noundef nonnull ptr @f(ptr noalias noundef nonnull readnone returned {{(captures\(ret: address, provenance\))?}} %x) unnamed_addr
+#[no_mangle]
+pub fn f(x: ManuallyDrop<Box<u8>>) -> ManuallyDrop<Box<u8>> {
+    x
+}
+
+// CHECK: define {{(dso_local )?}}noundef nonnull ptr @g(ptr noalias noundef readonly returned {{(captures\(ret: address, read_provenance\))?}} dereferenceable(1) %x) unnamed_addr
+#[no_mangle]
+pub fn g(x: ManuallyDrop<&u8>) -> ManuallyDrop<&u8> {
+    x
+}
+
+// CHECK: define {{(dso_local )?}}noundef nonnull ptr @h(ptr noalias noundef readnone returned {{(captures\(ret: address, provenance\))?}} dereferenceable(1) %x) unnamed_addr
+#[no_mangle]
+pub fn h(x: ManuallyDrop<&mut u8>) -> ManuallyDrop<&mut u8> {
+    x
+}
+
+// CHECK: define {{(dso_local )?}}noundef nonnull align 4 ptr @i(ptr noalias noundef nonnull readnone returned align 4 {{(captures\(ret: address, provenance\))?}} %x) unnamed_addr
+#[no_mangle]
+pub fn i(x: ManuallyDrop<Box<u32>>) -> ManuallyDrop<Box<u32>> {
+    x
+}
+
+// CHECK: define {{(dso_local )?}}noundef nonnull align 4 ptr @j(ptr noalias noundef readonly returned align 4 {{(captures\(ret: address, read_provenance\))?}} dereferenceable(4) %x) unnamed_addr
+#[no_mangle]
+pub fn j(x: ManuallyDrop<&u32>) -> ManuallyDrop<&u32> {
+    x
+}
+
+// CHECK: define {{(dso_local )?}}noundef nonnull align 4 ptr @k(ptr noalias noundef readnone returned align 4 {{(captures\(ret: address, provenance\))?}} dereferenceable(4) %x) unnamed_addr
+#[no_mangle]
+pub fn k(x: ManuallyDrop<&mut u32>) -> ManuallyDrop<&mut u32> {
+    x
+}