remvoe to_scalar_ptr and use ref_to_mplace everywhere

Author: RalfJung

src/librustc_mir/interpret/intern.rs

@@ -192,20 +192,18 @@ for
         let ty = mplace.layout.ty;
         if let ty::Ref(_, referenced_ty, mutability) = ty.kind {
             let value = self.ecx.read_immediate(mplace.into())?;
+            let mplace = self.ecx.ref_to_mplace(value)?;
             // Handle trait object vtables
-            if let Ok(meta) = value.to_meta() {
-                if let ty::Dynamic(..) =
-                    self.ecx.tcx.struct_tail_erasing_lifetimes(
-                        referenced_ty, self.ecx.param_env).kind
-                {
-                    if let Ok(vtable) = meta.unwrap().to_ptr() {
-                        // explitly choose `Immutable` here, since vtables are immutable, even
-                        // if the reference of the fat pointer is mutable
-                        self.intern_shallow(vtable.alloc_id, Mutability::Immutable, None)?;
-                    }
+            if let ty::Dynamic(..) =
+                self.ecx.tcx.struct_tail_erasing_lifetimes(
+                    referenced_ty, self.ecx.param_env).kind
+            {
+                if let Ok(vtable) = mplace.meta.unwrap().to_ptr() {
+                    // explitly choose `Immutable` here, since vtables are immutable, even
+                    // if the reference of the fat pointer is mutable
+                    self.intern_shallow(vtable.alloc_id, Mutability::Immutable, None)?;
                 }
             }
-            let mplace = self.ecx.ref_to_mplace(value)?;
             // Check if we have encountered this pointer+layout combination before.
             // Only recurse for allocation-backed pointers.
             if let Scalar::Ptr(ptr) = mplace.ptr {
@@ -230,7 +228,7 @@ for
                             ty::Array(_, n)
                                 if n.eval_usize(self.ecx.tcx.tcx, self.ecx.param_env) == 0 => {}
                             ty::Slice(_)
-                                if value.to_meta().unwrap().unwrap().to_usize(self.ecx)? == 0 => {}
+                                if mplace.meta.unwrap().to_usize(self.ecx)? == 0 => {}
                             _ => bug!("const qualif failed to prevent mutable references"),
                         }
                     },

src/librustc_mir/interpret/operand.rs

@@ -82,26 +82,6 @@ impl<'tcx, Tag> Immediate<Tag> {
             Immediate::ScalarPair(a, b) => Ok((a.not_undef()?, b.not_undef()?))
         }
     }
-
-    /// Converts the immediate into a pointer (or a pointer-sized integer).
-    /// Throws away the second half of a ScalarPair!
-    #[inline]
-    pub fn to_scalar_ptr(self) -> InterpResult<'tcx, Scalar<Tag>> {
-        match self {
-            Immediate::Scalar(ptr) |
-            Immediate::ScalarPair(ptr, _) => ptr.not_undef(),
-        }
-    }
-
-    /// Converts the value into its metadata.
-    /// Throws away the first half of a ScalarPair!
-    #[inline]
-    pub fn to_meta(self) -> InterpResult<'tcx, Option<Scalar<Tag>>> {
-        Ok(match self {
-            Immediate::Scalar(_) => None,
-            Immediate::ScalarPair(_, meta) => Some(meta.not_undef()?),
-        })
-    }
 }
 
 // ScalarPair needs a type to interpret, so we often have an immediate and a type together

src/librustc_mir/interpret/place.rs

@@ -291,15 +291,19 @@ where
             .expect("`ref_to_mplace` called on non-ptr type")
             .ty;
         let layout = self.layout_of(pointee_type)?;
+        let (ptr, meta) = match *val {
+            Immediate::Scalar(ptr) => (ptr.not_undef()?, None),
+            Immediate::ScalarPair(ptr, meta) => (ptr.not_undef()?, Some(meta.not_undef()?)),
+        };
 
         let mplace = MemPlace {
-            ptr: val.to_scalar_ptr()?,
+            ptr,
             // We could use the run-time alignment here. For now, we do not, because
             // the point of tracking the alignment here is to make sure that the *static*
             // alignment information emitted with the loads is correct. The run-time
             // alignment can only be more restrictive.
             align: layout.align.abi,
-            meta: val.to_meta()?,
+            meta,
         };
         Ok(MPlaceTy { mplace, layout })
     }

src/librustc_mir/interpret/validity.rs

@@ -388,44 +388,31 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 }
             }
             ty::RawPtr(..) => {
-                // Check pointer part.
-                if self.ref_tracking_for_consts.is_some() {
-                    // Integers/floats in CTFE: For consistency with integers, we do not
-                    // accept undef.
-                    let _ptr = try_validation!(value.to_scalar_ptr(),
-                        "undefined address in raw pointer", self.path);
-                } else {
-                    // Remain consistent with `usize`: Accept anything.
-                }
-
-                // Check metadata.
-                let meta = try_validation!(value.to_meta(),
-                    "uninitialized data in wide pointer metadata", self.path);
-                let layout = self.ecx.layout_of(value.layout.ty.builtin_deref(true).unwrap().ty)?;
-                if layout.is_unsized() {
-                    self.check_wide_ptr_meta(meta, layout)?;
+                // We are conservative with undef for integers, but try to
+                // actually enforce our current rules for raw pointers.
+                let place = try_validation!(self.ecx.ref_to_mplace(value),
+                    "undefined pointer", self.path);
+                if place.layout.is_unsized() {
+                    self.check_wide_ptr_meta(place.meta, place.layout)?;
                 }
             }
             _ if ty.is_box() || ty.is_region_ptr() => {
                 // Handle wide pointers.
                 // Check metadata early, for better diagnostics
-                let ptr = try_validation!(value.to_scalar_ptr(),
-                    "undefined address in pointer", self.path);
-                let meta = try_validation!(value.to_meta(),
-                    "uninitialized data in wide pointer metadata", self.path);
-                let layout = self.ecx.layout_of(value.layout.ty.builtin_deref(true).unwrap().ty)?;
-                if layout.is_unsized() {
-                    self.check_wide_ptr_meta(meta, layout)?;
+                let place = try_validation!(self.ecx.ref_to_mplace(value),
+                    "undefined pointer", self.path);
+                if place.layout.is_unsized() {
+                    self.check_wide_ptr_meta(place.meta, place.layout)?;
                 }
                 // Make sure this is dereferencable and all.
-                let (size, align) = self.ecx.size_and_align_of(meta, layout)?
+                let (size, align) = self.ecx.size_and_align_of(place.meta, place.layout)?
                     // for the purpose of validity, consider foreign types to have
                     // alignment and size determined by the layout (size will be 0,
                     // alignment should take attributes into account).
-                    .unwrap_or_else(|| (layout.size, layout.align.abi));
+                    .unwrap_or_else(|| (place.layout.size, place.layout.align.abi));
                 let ptr: Option<_> = match
                     self.ecx.memory.check_ptr_access_align(
-                        ptr,
+                        place.ptr,
                         size,
                         Some(align),
                         CheckInAllocMsg::InboundsTest,
@@ -435,7 +422,7 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                     Err(err) => {
                         info!(
                             "{:?} did not pass access check for size {:?}, align {:?}",
-                            ptr, size, align
+                            place.ptr, size, align
                         );
                         match err.kind {
                             err_unsup!(InvalidNullPointerUsage) =>
@@ -459,7 +446,6 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 };
                 // Recursive checking
                 if let Some(ref mut ref_tracking) = self.ref_tracking_for_consts {
-                    let place = self.ecx.ref_to_mplace(value)?;
                     if let Some(ptr) = ptr { // not a ZST
                         // Skip validation entirely for some external statics
                         let alloc_kind = self.ecx.tcx.alloc_map.lock().get(ptr.alloc_id);