diff options
| -rw-r--r-- | library/core/src/ptr/const_ptr.rs | 44 | ||||
| -rw-r--r-- | library/core/src/ptr/mut_ptr.rs | 44 |
2 files changed, 66 insertions, 22 deletions
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs index 9a18857d49f..0a74c03d70f 100644 --- a/library/core/src/ptr/const_ptr.rs +++ b/library/core/src/ptr/const_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::mem; use crate::slice::{self, SliceIndex}; @@ -34,12 +34,23 @@ impl<T: ?Sized> *const 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 *const u8).guaranteed_eq(null()) { - None => false, - Some(res) => res, + #[inline] + fn runtime_impl(ptr: *const u8) -> bool { + ptr.addr() == 0 } + + #[inline] + const fn const_impl(ptr: *const 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 *const u8,), const_impl, runtime_impl) } } /// Casts to a pointer of another type. @@ -1587,11 +1598,22 @@ impl<T: ?Sized> *const T { 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: *const (), align: usize) -> bool { + ptr.addr() & (align - 1) == 0 + } + + #[inline] + const fn const_impl(ptr: *const (), 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) } } } diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs index 8b9c1f7780a..d70fb70c79f 100644 --- 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. @@ -1859,11 +1870,22 @@ impl<T: ?Sized> *mut T { 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) } } } |