Merge pull request #4570 from RalfJung/atomic-rmw-int

atomic rmw intrinsics: RHS must be an integer

Author: RalfJung

src/intrinsics/atomic.rs

@@ -264,8 +264,9 @@ trait EvalContextPrivExt<'tcx>: MiriInterpCxExt<'tcx> {
         let place = this.deref_pointer(place)?;
         let rhs = this.read_immediate(rhs)?;
 
+        // The LHS can be a pointer, the RHS must be an integer.
         if !(place.layout.ty.is_integral() || place.layout.ty.is_raw_ptr())
-            || !(rhs.layout.ty.is_integral() || rhs.layout.ty.is_raw_ptr())
+            || !rhs.layout.ty.is_integral()
         {
             span_bug!(
                 this.cur_span(),