Auto merge of #61781 - christianpoveda:intptrcast-model, r=oli-obk,RalfJung

prepare for Intptrcast model

#61668 done right (I hope so). r? @RalfJung @oli-obk

Author: bors

Diff for: src/librustc_mir/interpret/eval_context.rs

@@ -765,4 +765,21 @@ 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>,
+        size: Size
+    ) -> InterpResult<'tcx, u128> {
+        self.memory.force_bits(scalar, size)
+    }
 }

Diff for: 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 +209,22 @@ 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>> {
+        if int == 0 {
+            Err(InterpErrorInfo::from(InterpError::InvalidNullPointerUsage))
+        } else {
+            Err(InterpErrorInfo::from(InterpError::ReadBytesAsPointer))
+        }
+    }
+
+    fn ptr_to_int(
+        _ptr: Pointer<Self::PointerTag>,
+        _extra: &Self::MemoryExtra,
+    ) -> InterpResult<'tcx, u64> {
+        Err(InterpErrorInfo::from(InterpError::ReadPointerAsBytes))
+    }
 }

Diff for: src/librustc_mir/interpret/memory.rs

@@ -627,7 +627,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         if size.bytes() == 0 {
             Ok(&[])
         } else {
-            let ptr = ptr.to_ptr()?;
+            let ptr = self.force_ptr(ptr)?;
             self.get(ptr.alloc_id)?.get_bytes(self, ptr, size)
         }
     }
@@ -714,8 +714,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             // non-NULLness which already happened.
             return Ok(());
         }
-        let src = src.to_ptr()?;
-        let dest = dest.to_ptr()?;
+        let src = self.force_ptr(src)?;
+        let dest = self.force_ptr(dest)?;
 
         // first copy the relocations to a temporary buffer, because
         // `get_bytes_mut` will clear the relocations, which is correct,
@@ -874,4 +874,25 @@ 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>,
+        size: Size
+    ) -> InterpResult<'tcx, u128> {
+        match scalar.to_bits_or_ptr(size, self) {
+            Ok(bits) => Ok(bits),
+            Err(ptr) => Ok(M::ptr_to_int(ptr, &self.extra)? as u128)
+        }
+    }
 }

Diff for: src/librustc_mir/interpret/operand.rs

@@ -232,7 +232,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
         }
 
         // check for integer pointers before alignment to report better errors
-        let ptr = ptr.to_ptr()?;
+        let ptr = self.force_ptr(ptr)?;
         self.memory.check_align(ptr.into(), ptr_align)?;
         match mplace.layout.abi {
             layout::Abi::Scalar(..) => {

Diff for: src/librustc_mir/interpret/operator.rs

@@ -347,7 +347,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
             }
             _ => {
                 assert!(layout.ty.is_integral());
-                let val = val.to_bits(layout.size)?;
+                let val = self.force_bits(val, layout.size)?;
                 let res = match un_op {
                     Not => !val,
                     Neg => {

Diff for: src/librustc_mir/interpret/place.rs

@@ -473,7 +473,7 @@ where
                 let layout = self.layout_of(self.tcx.types.usize)?;
                 let n = self.access_local(self.frame(), local, Some(layout))?;
                 let n = self.read_scalar(n)?;
-                let n = n.to_bits(self.tcx.data_layout.pointer_size)?;
+                let n = self.force_bits(n.not_undef()?, self.tcx.data_layout.pointer_size)?;
                 self.mplace_field(base, u64::try_from(n).unwrap())?
             }
 
@@ -753,7 +753,7 @@ where
         }
 
         // check for integer pointers before alignment to report better errors
-        let ptr = ptr.to_ptr()?;
+        let ptr = self.force_ptr(ptr)?;
         self.memory.check_align(ptr.into(), ptr_align)?;
         let tcx = &*self.tcx;
         // FIXME: We should check that there are dest.layout.size many bytes available in

Diff for: src/librustc_mir/interpret/terminator.rs

@@ -79,7 +79,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
                 let (fn_def, abi) = match func.layout.ty.sty {
                     ty::FnPtr(sig) => {
                         let caller_abi = sig.abi();
-                        let fn_ptr = self.read_scalar(func)?.to_ptr()?;
+                        let fn_ptr = self.force_ptr(self.read_scalar(func)?.not_undef()?)?;
                         let instance = self.memory.get_fn(fn_ptr)?;
                         (instance, caller_abi)
                     }

Diff for: src/librustc_mir/interpret/validity.rs

@@ -559,7 +559,7 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 // This is the size in bytes of the whole array.
                 let size = ty_size * len;
 
-                let ptr = mplace.ptr.to_ptr()?;
+                let ptr = self.ecx.force_ptr(mplace.ptr)?;
 
                 // NOTE: Keep this in sync with the handling of integer and float
                 // types above, in `visit_primitive`.