1 files changed, 33 insertions, 0 deletions
diff --git a/src/librustc/mir/interpret/allocation.rs b/src/librustc/mir/interpret/allocation.rs
index 2334ca2f91a..ad4bf415b8d 100644
--- a/src/librustc/mir/interpret/allocation.rs
+++ b/src/librustc/mir/interpret/allocation.rs
@@ -206,6 +206,39 @@ impl<'tcx, Tag, Extra> Allocation<Tag, Extra> {
     }
 }
 
+
+/// Undefined bytes
+impl<'tcx, Tag, Extra> Allocation<Tag, Extra> {
+    /// Checks that a range of bytes is defined. If not, returns the `ReadUndefBytes`
+    /// error which will report the first byte which is undefined.
+    #[inline]
+    fn check_defined(&self, ptr: Pointer<M::PointerTag>, size: Size) -> EvalResult<'tcx> {
+        let alloc = self.get(ptr.alloc_id)?;
+        alloc.undef_mask.is_range_defined(
+            ptr.offset,
+            ptr.offset + size,
+        ).or_else(|idx| err!(ReadUndefBytes(idx)))
+    }
+
+    pub fn mark_definedness(
+        &mut self,
+        ptr: Pointer<M::PointerTag>,
+        size: Size,
+        new_state: bool,
+    ) -> EvalResult<'tcx> {
+        if size.bytes() == 0 {
+            return Ok(());
+        }
+        let alloc = self.get_mut(ptr.alloc_id)?;
+        alloc.undef_mask.set_range(
+            ptr.offset,
+            ptr.offset + size,
+            new_state,
+        );
+        Ok(())
+    }
+}
+
 pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Default + Clone {
     /// Hook for performing extra checks on a memory read access.
     ///