Add force_bits and force_ptr methods

src/librustc_mir/interpret/eval_context.rs

@@ -765,4 +765,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
     pub fn truncate(&self, value: u128, ty: TyLayout<'_>) -> u128 {
         truncate(value, ty.size)
     }
+
+    #[inline(always)]
+    pub fn force_ptr(
+        &self,
+        scalar: Scalar<M::PointerTag>,
+    ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
+        self.memory.force_ptr(scalar)
+    }
+
+    #[inline(always)]
+    pub fn force_bits(&self, scalar: Scalar<M::PointerTag>) -> InterpResult<'tcx, u128> {
+        self.memory.force_bits(scalar)
+    }
 }

src/librustc_mir/interpret/machine.rs

@@ -11,7 +11,8 @@ use rustc::ty::{self, query::TyCtxtAt};
 
 use super::{
     Allocation, AllocId, InterpResult, Scalar, AllocationExtra,
-    InterpretCx, PlaceTy, OpTy, ImmTy, MemoryKind,
+    InterpretCx, PlaceTy, OpTy, ImmTy, MemoryKind, Pointer,
+    InterpErrorInfo, InterpError
 };
 
 /// Whether this kind of memory is allowed to leak
@@ -208,4 +209,18 @@ pub trait Machine<'mir, 'tcx>: Sized {
         ecx: &mut InterpretCx<'mir, 'tcx, Self>,
         extra: Self::FrameExtra,
     ) -> InterpResult<'tcx>;
+
+    fn int_to_ptr(
+        _int: u64,
+        _extra: &Self::MemoryExtra,
+    ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
+        Err(InterpErrorInfo::from(InterpError::ReadBytesAsPointer))
+    }
+
+    fn ptr_to_int(
+        _ptr: Pointer<Self::PointerTag>,
+        _extra: &Self::MemoryExtra,
+    ) -> InterpResult<'tcx, u64> {
+        Err(InterpErrorInfo::from(InterpError::ReadPointerAsBytes))
+    }
 }

src/librustc_mir/interpret/memory.rs

@@ -874,4 +874,21 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         }
         Ok(())
     }
+
+    pub fn force_ptr(
+        &self,
+        scalar: Scalar<M::PointerTag>,
+    ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
+        match scalar {
+            Scalar::Ptr(ptr) => Ok(ptr),
+            _ => M::int_to_ptr(scalar.to_usize(self)?, &self.extra)
+        }
+    }
+
+    pub fn force_bits(&self, scalar: Scalar<M::PointerTag>) -> InterpResult<'tcx, u128> {
+        match scalar.to_bits_or_ptr(self.pointer_size(), self) {
+            Ok(bits) => Ok(bits),
+            Err(ptr) => Ok(M::ptr_to_int(ptr, &self.extra)? as u128)
+        }
+    }
 }