Don't run ptr_op for pure integer values

Author: oli-obk

miri/operator.rs

@@ -48,7 +48,7 @@ impl<'a, 'tcx> EvalContextExt<'tcx> for EvalContext<'a, 'tcx, super::Evaluator>
             // These work on anything
             Eq if left_kind == right_kind => {
                 let result = match (left, right) {
-                    (PrimVal::Bytes(left), PrimVal::Bytes(right)) => left == right,
+                    (PrimVal::Bytes(_), PrimVal::Bytes(_)) => bug!("wrong usage of `ptr_op` by `interpret`"),
                     (PrimVal::Ptr(left), PrimVal::Ptr(right)) => left == right,
                     (PrimVal::Undef, _) | (_, PrimVal::Undef) => return Err(EvalError::ReadUndefBytes),
                     _ => false,
@@ -57,7 +57,7 @@ impl<'a, 'tcx> EvalContextExt<'tcx> for EvalContext<'a, 'tcx, super::Evaluator>
             }
             Ne if left_kind == right_kind => {
                 let result = match (left, right) {
-                    (PrimVal::Bytes(left), PrimVal::Bytes(right)) => left != right,
+                    (PrimVal::Bytes(_), PrimVal::Bytes(_)) => bug!("wrong usage of `ptr_op` by `interpret`"),
                     (PrimVal::Ptr(left), PrimVal::Ptr(right)) => left != right,
                     (PrimVal::Undef, _) | (_, PrimVal::Undef) => return Err(EvalError::ReadUndefBytes),
                     _ => true,

src/librustc_mir/interpret/machine.rs

@@ -55,6 +55,8 @@ pub trait Machine<'tcx>: Sized {
     /// Returns `None` if the operation should be handled by the integer
     /// op code
     ///
+    /// It is guaranteed that `left` and `right` are never both `PrimVal::Ptr`
+    ///
     /// Returns a (value, overflowed) pair otherwise
     fn ptr_op<'a>(
         ecx: &EvalContext<'a, 'tcx, Self>,

src/librustc_mir/interpret/operator.rs

@@ -153,8 +153,10 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
 
         // I: Handle operations that support pointers
         if !left_kind.is_float() && !right_kind.is_float() {
-            if let Some(handled) = M::ptr_op(self, bin_op, left, left_ty, right, right_ty)? {
-                return Ok(handled);
+            if left.is_ptr() != right.is_ptr() {
+                if let Some(handled) = M::ptr_op(self, bin_op, left, left_ty, right, right_ty)? {
+                    return Ok(handled);
+                }
             }
         }