From 53565b23ac21bc15be1feab9fb316fce7a73e21c Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Fri, 19 Aug 2022 13:20:22 +0400
Subject: [PATCH] Make use of `[wrapping_]byte_{add,sub}`
...replacing `.cast().wrapping_offset().cast()` & similar code.
---
compiler/rustc_arena/src/lib.rs | 3 ++-
library/alloc/src/vec/into_iter.rs | 13 +++++--------
library/alloc/src/vec/mod.rs | 4 ++--
library/core/src/ptr/const_ptr.rs | 2 +-
library/core/src/ptr/mut_ptr.rs | 2 +-
library/core/src/slice/iter/macros.rs | 2 +-
library/core/tests/atomic.rs | 2 +-
library/core/tests/ptr.rs | 2 +-
library/std/src/io/error/repr_bitpacked.rs | 4 ++--
library/std/src/lib.rs | 1 +
10 files changed, 17 insertions(+), 18 deletions(-)
diff --git a/compiler/rustc_arena/src/lib.rs b/compiler/rustc_arena/src/lib.rs
index d2f8ef8eaae7d..46dbbd83d1905 100644
--- a/compiler/rustc_arena/src/lib.rs
+++ b/compiler/rustc_arena/src/lib.rs
@@ -16,6 +16,7 @@
#![feature(maybe_uninit_slice)]
#![feature(min_specialization)]
#![feature(decl_macro)]
+#![feature(pointer_byte_offsets)]
#![feature(rustc_attrs)]
#![cfg_attr(test, feature(test))]
#![feature(strict_provenance)]
@@ -211,7 +212,7 @@ impl<T> TypedArena<T> {
unsafe {
if mem::size_of::<T>() == 0 {
- self.ptr.set((self.ptr.get() as *mut u8).wrapping_offset(1) as *mut T);
+ self.ptr.set(self.ptr.get().wrapping_byte_add(1));
let ptr = ptr::NonNull::<T>::dangling().as_ptr();
// Don't drop the object. This `write` is equivalent to `forget`.
ptr::write(ptr, object);
diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
index 4351548811d2e..ed049194dd068 100644
--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
@@ -4,7 +4,6 @@ use crate::alloc::{Allocator, Global};
use crate::raw_vec::RawVec;
use core::array;
use core::fmt;
-use core::intrinsics::arith_offset;
use core::iter::{
FusedIterator, InPlaceIterable, SourceIter, TrustedLen, TrustedRandomAccessNoCoerce,
};
@@ -154,7 +153,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
// purposefully don't use 'ptr.offset' because for
// vectors with 0-size elements this would return the
// same pointer.
- self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T };
+ self.ptr = self.ptr.wrapping_byte_add(1);
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
@@ -184,7 +183,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
// SAFETY: due to unchecked casts of unsigned amounts to signed offsets the wraparound
// effectively results in unsigned pointers representing positions 0..usize::MAX,
// which is valid for ZSTs.
- self.ptr = unsafe { arith_offset(self.ptr as *const i8, step_size as isize) as *mut T }
+ self.ptr = self.ptr.wrapping_byte_add(step_size);
} else {
// SAFETY: the min() above ensures that step_size is in bounds
self.ptr = unsafe { self.ptr.add(step_size) };
@@ -217,7 +216,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
return Err(unsafe { array::IntoIter::new_unchecked(raw_ary, 0..len) });
}
- self.ptr = unsafe { arith_offset(self.ptr as *const i8, N as isize) as *mut T };
+ self.ptr = self.ptr.wrapping_byte_add(N);
// Safety: ditto
return Ok(unsafe { MaybeUninit::array_assume_init(raw_ary) });
}
@@ -267,7 +266,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
None
} else if mem::size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
- self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T };
+ self.end = self.ptr.wrapping_byte_sub(1);
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
@@ -283,9 +282,7 @@ impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
let step_size = self.len().min(n);
if mem::size_of::<T>() == 0 {
// SAFETY: same as for advance_by()
- self.end = unsafe {
- arith_offset(self.end as *const i8, step_size.wrapping_neg() as isize) as *mut T
- }
+ self.end = self.end.wrapping_byte_sub(step_size);
} else {
// SAFETY: same as for advance_by()
self.end = unsafe { self.end.sub(step_size) };
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 2c786fd511ead..1f19b9e594549 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -59,7 +59,7 @@ use core::cmp::Ordering;
use core::convert::TryFrom;
use core::fmt;
use core::hash::{Hash, Hasher};
-use core::intrinsics::{arith_offset, assume};
+use core::intrinsics::assume;
use core::iter;
#[cfg(not(no_global_oom_handling))]
use core::iter::FromIterator;
@@ -2678,7 +2678,7 @@ impl<T, A: Allocator> IntoIterator for Vec<T, A> {
let alloc = ManuallyDrop::new(ptr::read(me.allocator()));
let begin = me.as_mut_ptr();
let end = if mem::size_of::<T>() == 0 {
- arith_offset(begin as *const i8, me.len() as isize) as *const T
+ begin.wrapping_byte_add(me.len())
} else {
begin.add(me.len()) as *const T
};
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index c25b159c533a1..feba3283e468c 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -249,7 +249,7 @@ impl<T: ?Sized> *const T {
let offset = dest_addr.wrapping_sub(self_addr);
// This is the canonical desugarring of this operation
- self.cast::<u8>().wrapping_offset(offset).cast::<T>()
+ self.wrapping_byte_offset(offset)
}
/// Creates a new pointer by mapping `self`'s address to a new one.
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index fff06b458c7c1..a70f8747916c3 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -255,7 +255,7 @@ impl<T: ?Sized> *mut T {
let offset = dest_addr.wrapping_sub(self_addr);
// This is the canonical desugarring of this operation
- self.cast::<u8>().wrapping_offset(offset).cast::<T>()
+ self.wrapping_byte_offset(offset)
}
/// Creates a new pointer by mapping `self`'s address to a new one.
diff --git a/library/core/src/slice/iter/macros.rs b/library/core/src/slice/iter/macros.rs
index c05242222dde7..47455760a4bd7 100644
--- a/library/core/src/slice/iter/macros.rs
+++ b/library/core/src/slice/iter/macros.rs
@@ -64,7 +64,7 @@ macro_rules! iterator {
// backwards by `n`. `n` must not exceed `self.len()`.
macro_rules! zst_shrink {
($self: ident, $n: ident) => {
- $self.end = ($self.end as * $raw_mut u8).wrapping_offset(-$n) as * $raw_mut T;
+ $self.end = $self.end.wrapping_byte_offset(-$n);
}
}
diff --git a/library/core/tests/atomic.rs b/library/core/tests/atomic.rs
index 13b12db209a76..94b0310603bf4 100644
--- a/library/core/tests/atomic.rs
+++ b/library/core/tests/atomic.rs
@@ -155,7 +155,7 @@ fn ptr_add_data() {
assert_eq!(atom.fetch_ptr_sub(1, SeqCst), n.wrapping_add(1));
assert_eq!(atom.load(SeqCst), n);
- let bytes_from_n = |b| n.cast::<u8>().wrapping_add(b).cast::<i64>();
+ let bytes_from_n = |b| n.wrapping_byte_add(b);
assert_eq!(atom.fetch_byte_add(1, SeqCst), n);
assert_eq!(atom.load(SeqCst), bytes_from_n(1));
diff --git a/library/core/tests/ptr.rs b/library/core/tests/ptr.rs
index 12861794c2d2c..97a369810056d 100644
--- a/library/core/tests/ptr.rs
+++ b/library/core/tests/ptr.rs
@@ -650,7 +650,7 @@ fn thin_box() {
.unwrap_or_else(|| handle_alloc_error(layout))
.cast::<DynMetadata<T>>();
ptr.as_ptr().write(meta);
- ptr.cast::<u8>().as_ptr().add(offset).cast::<Value>().write(value);
+ ptr.as_ptr().byte_add(offset).cast::<Value>().write(value);
Self { ptr, phantom: PhantomData }
}
}
diff --git a/library/std/src/io/error/repr_bitpacked.rs b/library/std/src/io/error/repr_bitpacked.rs
index 292bf4826fd23..781ae03ad45dc 100644
--- a/library/std/src/io/error/repr_bitpacked.rs
+++ b/library/std/src/io/error/repr_bitpacked.rs
@@ -269,10 +269,10 @@ where
}
TAG_SIMPLE_MESSAGE => ErrorData::SimpleMessage(&*ptr.cast::<SimpleMessage>().as_ptr()),
TAG_CUSTOM => {
- // It would be correct for us to use `ptr::sub` here (see the
+ // It would be correct for us to use `ptr::byte_sub` here (see the
// comment above the `wrapping_add` call in `new_custom` for why),
// but it isn't clear that it makes a difference, so we don't.
- let custom = ptr.as_ptr().cast::<u8>().wrapping_sub(TAG_CUSTOM).cast::<Custom>();
+ let custom = ptr.as_ptr().wrapping_byte_sub(TAG_CUSTOM).cast::<Custom>();
ErrorData::Custom(make_custom(custom))
}
_ => {
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 71bbf4317e0a5..ba16a5c68ad9e 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -296,6 +296,7 @@
#![feature(panic_can_unwind)]
#![feature(panic_info_message)]
#![feature(panic_internals)]
+#![feature(pointer_byte_offsets)]
#![feature(pointer_is_aligned)]
#![feature(portable_simd)]
#![feature(prelude_2024)]