Constify intrinsics::copy[_nonoverlapping]

Author: usbalbin

compiler/rustc_mir/src/interpret/intrinsics.rs

@@ -322,6 +322,29 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let result = Scalar::from_uint(truncated_bits, layout.size);
                 self.write_scalar(result, dest)?;
             }
+            sym::copy | sym::copy_nonoverlapping => {
+                let elem_ty = instance.substs.type_at(0);
+                let elem_layout = self.layout_of(elem_ty)?;
+                let count = self.read_scalar(args[2])?.to_machine_usize(self)?;
+                let elem_align = elem_layout.align.abi;
+
+                let size = elem_layout.size.checked_mul(count, self).ok_or_else(|| {
+                    err_ub_format!("overflow computing total size of `{}`", intrinsic_name)
+                })?;
+                let src = self.read_scalar(args[0])?.check_init()?;
+                let src = self.memory.check_ptr_access(src, size, elem_align)?;
+                let dest = self.read_scalar(args[1])?.check_init()?;
+                let dest = self.memory.check_ptr_access(dest, size, elem_align)?;
+
+                if let (Some(src), Some(dest)) = (src, dest) {
+                    self.memory.copy(
+                        src,
+                        dest,
+                        size,
+                        intrinsic_name == sym::copy_nonoverlapping,
+                    )?;
+                }
+            }
             sym::offset => {
                 let ptr = self.read_scalar(args[0])?.check_init()?;
                 let offset_count = self.read_scalar(args[1])?.to_machine_isize(self)?;

library/core/src/intrinsics.rs

@@ -1846,20 +1846,22 @@ pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -
 /// [`Vec::append`]: ../../std/vec/struct.Vec.html#method.append
 #[doc(alias = "memcpy")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "none")]
 #[inline]
-pub unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
+pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 
-    if cfg!(debug_assertions)
+    // FIXME: Perform these checks only at run time
+    /*if cfg!(debug_assertions)
         && !(is_aligned_and_not_null(src)
             && is_aligned_and_not_null(dst)
             && is_nonoverlapping(src, dst, count))
     {
         // Not panicking to keep codegen impact smaller.
         abort();
-    }
+    }*/
 
     // SAFETY: the safety contract for `copy_nonoverlapping` must be
     // upheld by the caller.
@@ -1928,16 +1930,19 @@ pub unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
 /// ```
 #[doc(alias = "memmove")]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "none")]
 #[inline]
-pub unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
+pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
+        #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "none")]
         fn copy<T>(src: *const T, dst: *mut T, count: usize);
     }
 
-    if cfg!(debug_assertions) && !(is_aligned_and_not_null(src) && is_aligned_and_not_null(dst)) {
+    // FIXME: Perform these checks only at run time
+    /*if cfg!(debug_assertions) && !(is_aligned_and_not_null(src) && is_aligned_and_not_null(dst)) {
         // Not panicking to keep codegen impact smaller.
         abort();
-    }
+    }*/
 
     // SAFETY: the safety contract for `copy` must be upheld by the caller.
     unsafe { copy(src, dst, count) }