Use pointer type in AtomicPtr::swap implementation

1 files changed, 13 insertions, 2 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
index 34022643101..80e3ed75b85 100644
--- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
@@ -524,8 +524,19 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         };
 
                         let ty = substs.type_at(0);
-                        if int_type_width_signed(ty, bx.tcx()).is_some() {
-                            bx.atomic_rmw(atom_op, args[0].immediate(), args[1].immediate(), order)
+                        if int_type_width_signed(ty, bx.tcx()).is_some()
+                            || (ty.is_unsafe_ptr() && op == "xchg")
+                        {
+                            let mut ptr = args[0].immediate();
+                            let mut val = args[1].immediate();
+                            if ty.is_unsafe_ptr() {
+                                // Some platforms do not support atomic operations on pointers,
+                                // so we cast to integer first.
+                                let ptr_llty = bx.type_ptr_to(bx.type_isize());
+                                ptr = bx.pointercast(ptr, ptr_llty);
+                                val = bx.ptrtoint(val, bx.type_isize());
+                            }
+                            bx.atomic_rmw(atom_op, ptr, val, order)
                         } else {
                             return invalid_monomorphization(ty);
                         }