Rollup merge of #106854 - steffahn:drop_linear_arc_rebased, r=Mark-Simulacrum

[rust.git] / library / core / src / ptr / mut_ptr.rs

diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index 8b9c1f7780ae4c3da09a3d1a028f361f0da2fd92..ed1e3bd48122761607f22a10f0bfb11608c0d892 100644 (file)
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -1,6 +1,6 @@
 use super::*;
 use crate::cmp::Ordering::{self, Equal, Greater, Less};
-use crate::intrinsics;
+use crate::intrinsics::{self, const_eval_select};
 use crate::slice::{self, SliceIndex};
 
 impl<T: ?Sized> *mut T {
@@ -33,12 +33,23 @@ impl<T: ?Sized> *mut T {
     #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
     #[inline]
     pub const fn is_null(self) -> bool {
-        // Compare via a cast to a thin pointer, so fat pointers are only
-        // considering their "data" part for null-ness.
-        match (self as *mut u8).guaranteed_eq(null_mut()) {
-            None => false,
-            Some(res) => res,
+        #[inline]
+        fn runtime_impl(ptr: *mut u8) -> bool {
+            ptr.addr() == 0
         }
+
+        #[inline]
+        const fn const_impl(ptr: *mut u8) -> bool {
+            // Compare via a cast to a thin pointer, so fat pointers are only
+            // considering their "data" part for null-ness.
+            match (ptr).guaranteed_eq(null_mut()) {
+                None => false,
+                Some(res) => res,
+            }
+        }
+
+        // SAFETY: The two versions are equivalent at runtime.
+        unsafe { const_eval_select((self as *mut u8,), const_impl, runtime_impl) }
     }
 
     /// Casts to a pointer of another type.
@@ -197,14 +208,11 @@ pub fn from_bits(bits: usize) -> Self
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         // SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
         // provenance).
-        unsafe { mem::transmute(self) }
+        unsafe { mem::transmute(self.cast::<()>()) }
     }
 
     /// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
@@ -234,12 +242,9 @@ pub fn addr(self) -> usize
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn expose_addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn expose_addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
-        self as usize
+        self.cast::<()>() as usize
     }
 
     /// Creates a new pointer with the given address.
@@ -257,10 +262,7 @@ pub fn expose_addr(self) -> usize
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn with_addr(self, addr: usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn with_addr(self, addr: usize) -> Self {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         //
         // In the mean-time, this operation is defined to be "as if" it was
@@ -283,10 +285,7 @@ pub fn with_addr(self, addr: usize) -> Self
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self {
         self.with_addr(f(self.addr()))
     }
 
@@ -1859,11 +1858,22 @@ pub const fn is_aligned_to(self, align: usize) -> bool {
             panic!("is_aligned_to: align is not a power-of-two");
         }
 
-        // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead.
-        // The cast to `()` is used to
-        //   1. deal with fat pointers; and
-        //   2. ensure that `align_offset` doesn't actually try to compute an offset.
-        self.cast::<()>().align_offset(align) == 0
+        #[inline]
+        fn runtime_impl(ptr: *mut (), align: usize) -> bool {
+            ptr.addr() & (align - 1) == 0
+        }
+
+        #[inline]
+        const fn const_impl(ptr: *mut (), align: usize) -> bool {
+            // We can't use the address of `self` in a `const fn`, so we use `align_offset` instead.
+            // The cast to `()` is used to
+            //   1. deal with fat pointers; and
+            //   2. ensure that `align_offset` doesn't actually try to compute an offset.
+            ptr.align_offset(align) == 0
+        }
+
+        // SAFETY: The two versions are equivalent at runtime.
+        unsafe { const_eval_select((self.cast::<()>(), align), const_impl, runtime_impl) }
     }
 }