1 files changed, 84 insertions, 0 deletions
diff --git a/tests/codegen-llvm/dst-offset.rs b/tests/codegen-llvm/dst-offset.rs
new file mode 100644
index 00000000000..2cf5fa9fac6
--- /dev/null
+++ b/tests/codegen-llvm/dst-offset.rs
@@ -0,0 +1,84 @@
+//! This file tests that we correctly generate GEP instructions for DST
+//! field offsets.
+//@ compile-flags: -C no-prepopulate-passes -Copt-level=0
+
+#![crate_type = "lib"]
+#![feature(extern_types, sized_hierarchy)]
+
+use std::marker::PointeeSized;
+use std::ptr::addr_of;
+
+// Hack to get the correct type for usize
+// CHECK: @helper([[USIZE:i[0-9]+]] %_1)
+#[no_mangle]
+pub fn helper(_: usize) {}
+
+struct Dst<T: PointeeSized> {
+    x: u32,
+    y: u8,
+    z: T,
+}
+
+// CHECK: @dst_dyn_trait_offset(ptr align {{[0-9]+}} [[DATA_PTR:%.+]], ptr align {{[0-9]+}} [[VTABLE_PTR:%.+]])
+#[no_mangle]
+pub fn dst_dyn_trait_offset(s: &Dst<dyn Drop>) -> &dyn Drop {
+    // The alignment of dyn trait is unknown, so we compute the offset based on align from the
+    // vtable.
+
+    // CHECK: [[SIZE_PTR:%[0-9]+]] = getelementptr inbounds i8, ptr [[VTABLE_PTR]]
+    // CHECK: load [[USIZE]], ptr [[SIZE_PTR]]
+    // CHECK: [[ALIGN_PTR:%[0-9]+]] = getelementptr inbounds i8, ptr [[VTABLE_PTR]]
+    // CHECK: load [[USIZE]], ptr [[ALIGN_PTR]]
+
+    // CHECK: getelementptr inbounds i8, ptr [[DATA_PTR]]
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: ret
+    &s.z
+}
+
+// CHECK-LABEL: @dst_slice_offset
+#[no_mangle]
+pub fn dst_slice_offset(s: &Dst<[u16]>) -> &[u16] {
+    // The alignment of [u16] is known, so we generate a GEP directly.
+
+    // CHECK: start:
+    // CHECK-NEXT: getelementptr inbounds i8, {{.+}}, [[USIZE]] 6
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: ret
+    &s.z
+}
+
+#[repr(packed)]
+struct PackedDstSlice {
+    x: u32,
+    y: u8,
+    z: [u16],
+}
+
+// CHECK-LABEL: @packed_dst_slice_offset
+#[no_mangle]
+pub fn packed_dst_slice_offset(s: &PackedDstSlice) -> *const [u16] {
+    // The alignment of [u16] is known, so we generate a GEP directly.
+
+    // CHECK: start:
+    // CHECK-NEXT: getelementptr inbounds i8, {{.+}}, [[USIZE]] 5
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: insertvalue
+    // CHECK-NEXT: ret
+    addr_of!(s.z)
+}
+
+extern "C" {
+    pub type Extern;
+}
+
+// CHECK-LABEL: @dst_extern
+#[no_mangle]
+pub fn dst_extern(s: &Dst<Extern>) -> &Extern {
+    // Computing the alignment of an extern type is currently unsupported and just panics.
+
+    // CHECK: call void @{{.+}}panic
+    &s.z
+}