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Replace `Memoryblock` with `NonNull<[u8]>`

This commit is contained in:
Tim Diekmann 2020-08-04 18:03:34 +02:00
parent 5f6bd6ec0a
commit ab9362ad9a
17 changed files with 158 additions and 143 deletions
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30
library/alloc/src/alloc.rs
View File

@ -164,7 +164,7 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
#[unstable(feature = "allocator_api", issue = "32838")]
unsafe impl AllocRef for Global {
#[inline]
fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
let ptr = if size == 0 {
layout.dangling()
@ -172,11 +172,11 @@ unsafe impl AllocRef for Global {
// SAFETY: `layout` is non-zero in size,
unsafe { NonNull::new(alloc(layout)).ok_or(AllocErr)? }
};
Ok(MemoryBlock { ptr, size })
Ok(NonNull::slice_from_raw_parts(ptr, size))
}
#[inline]
fn alloc_zeroed(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
let ptr = if size == 0 {
layout.dangling()
@ -184,7 +184,7 @@ unsafe impl AllocRef for Global {
// SAFETY: `layout` is non-zero in size,
unsafe { NonNull::new(alloc_zeroed(layout)).ok_or(AllocErr)? }
};
Ok(MemoryBlock { ptr, size })
Ok(NonNull::slice_from_raw_parts(ptr, size))
}
#[inline]
@ -202,7 +202,7 @@ unsafe impl AllocRef for Global {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
debug_assert!(
new_size >= layout.size(),
"`new_size` must be greater than or equal to `layout.size()`"
@ -212,14 +212,16 @@ unsafe impl AllocRef for Global {
// Other conditions must be upheld by the caller
unsafe {
match layout.size() {
old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
old_size if old_size == new_size => {
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
0 => self.alloc(Layout::from_size_align_unchecked(new_size, layout.align())),
old_size => {
// `realloc` probably checks for `new_size > size` or something similar.
intrinsics::assume(new_size > old_size);
let raw_ptr = realloc(ptr.as_ptr(), layout, new_size);
let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
}
@ -231,7 +233,7 @@ unsafe impl AllocRef for Global {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
debug_assert!(
new_size >= layout.size(),
"`new_size` must be greater than or equal to `layout.size()`"
@ -241,7 +243,9 @@ unsafe impl AllocRef for Global {
// Other conditions must be upheld by the caller
unsafe {
match layout.size() {
old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
old_size if old_size == new_size => {
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
0 => self.alloc_zeroed(Layout::from_size_align_unchecked(new_size, layout.align())),
old_size => {
// `realloc` probably checks for `new_size > size` or something similar.
@ -249,7 +253,7 @@ unsafe impl AllocRef for Global {
let raw_ptr = realloc(ptr.as_ptr(), layout, new_size);
raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
}
@ -261,7 +265,7 @@ unsafe impl AllocRef for Global {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
let old_size = layout.size();
debug_assert!(
new_size <= old_size,
@ -288,7 +292,7 @@ unsafe impl AllocRef for Global {
NonNull::new(raw_ptr).ok_or(AllocErr)?
};
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
@ -300,7 +304,7 @@ unsafe impl AllocRef for Global {
unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
let layout = unsafe { Layout::from_size_align_unchecked(size, align) };
match Global.alloc(layout) {
Ok(memory) => memory.ptr.as_ptr(),
Ok(ptr) => ptr.as_non_null_ptr().as_ptr(),
Err(_) => handle_alloc_error(layout),
}
}

6
library/alloc/src/alloc/tests.rs
View File

@ -8,16 +8,16 @@ use test::Bencher;
fn allocate_zeroed() {
unsafe {
let layout = Layout::from_size_align(1024, 1).unwrap();
let memory =
let ptr =
Global.alloc_zeroed(layout.clone()).unwrap_or_else(|_| handle_alloc_error(layout));
let mut i = memory.ptr.cast::<u8>().as_ptr();
let mut i = ptr.as_non_null_ptr().as_ptr();
let end = i.add(layout.size());
while i < end {
assert_eq!(*i, 0);
i = i.offset(1);
}
Global.dealloc(memory.ptr, layout);
Global.dealloc(ptr.as_non_null_ptr(), layout);
}
}

4
library/alloc/src/boxed.rs
View File

@ -197,8 +197,7 @@ impl<T> Box<T> {
#[unstable(feature = "new_uninit", issue = "63291")]
pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
let layout = alloc::Layout::new::<mem::MaybeUninit<T>>();
let ptr =
Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).ptr.cast();
let ptr = Global.alloc(layout).unwrap_or_else(|_| alloc::handle_alloc_error(layout)).cast();
unsafe { Box::from_raw(ptr.as_ptr()) }
}
@ -226,7 +225,6 @@ impl<T> Box<T> {
let ptr = Global
.alloc_zeroed(layout)
.unwrap_or_else(|_| alloc::handle_alloc_error(layout))
.ptr
.cast();
unsafe { Box::from_raw(ptr.as_ptr()) }
}

3
library/alloc/src/lib.rs
View File

@ -104,6 +104,7 @@
#![feature(negative_impls)]
#![feature(new_uninit)]
#![feature(nll)]
#![feature(nonnull_slice_from_raw_parts)]
#![feature(optin_builtin_traits)]
#![feature(or_patterns)]
#![feature(pattern)]
@ -113,6 +114,8 @@
#![feature(rustc_attrs)]
#![feature(receiver_trait)]
#![feature(min_specialization)]
#![feature(slice_ptr_get)]
#![feature(slice_ptr_len)]
#![feature(staged_api)]
#![feature(std_internals)]
#![feature(str_internals)]

30
library/alloc/src/raw_vec.rs
View File

@ -1,7 +1,7 @@
#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "none")]
#![doc(hidden)]
use core::alloc::{LayoutErr, MemoryBlock};
use core::alloc::LayoutErr;
use core::cmp;
use core::mem::{self, ManuallyDrop, MaybeUninit};
use core::ops::Drop;
@ -186,14 +186,14 @@ impl<T, A: AllocRef> RawVec<T, A> {
AllocInit::Uninitialized => alloc.alloc(layout),
AllocInit::Zeroed => alloc.alloc_zeroed(layout),
};
let memory = match result {
Ok(memory) => memory,
let ptr = match result {
Ok(ptr) => ptr,
Err(_) => handle_alloc_error(layout),
};
Self {
ptr: unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) },
cap: Self::capacity_from_bytes(memory.size),
ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
cap: Self::capacity_from_bytes(ptr.len()),
alloc,
}
}
@ -384,9 +384,9 @@ impl<T, A: AllocRef> RawVec<T, A> {
excess / mem::size_of::<T>()
}
fn set_memory(&mut self, memory: MemoryBlock) {
self.ptr = unsafe { Unique::new_unchecked(memory.ptr.cast().as_ptr()) };
self.cap = Self::capacity_from_bytes(memory.size);
fn set_ptr(&mut self, ptr: NonNull<[u8]>) {
self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) };
self.cap = Self::capacity_from_bytes(ptr.len());
}
// This method is usually instantiated many times. So we want it to be as
@ -432,8 +432,8 @@ impl<T, A: AllocRef> RawVec<T, A> {
let new_layout = Layout::array::<T>(cap);
// `finish_grow` is non-generic over `T`.
let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
self.set_memory(memory);
let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
self.set_ptr(ptr);
Ok(())
}
@ -451,8 +451,8 @@ impl<T, A: AllocRef> RawVec<T, A> {
let new_layout = Layout::array::<T>(cap);
// `finish_grow` is non-generic over `T`.
let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
self.set_memory(memory);
let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
self.set_ptr(ptr);
Ok(())
}
@ -462,13 +462,13 @@ impl<T, A: AllocRef> RawVec<T, A> {
let (ptr, layout) = if let Some(mem) = self.current_memory() { mem } else { return Ok(()) };
let new_size = amount * mem::size_of::<T>();
let memory = unsafe {
let ptr = unsafe {
self.alloc.shrink(ptr, layout, new_size).map_err(|_| TryReserveError::AllocError {
layout: Layout::from_size_align_unchecked(new_size, layout.align()),
non_exhaustive: (),
})?
};
self.set_memory(memory);
self.set_ptr(ptr);
Ok(())
}
}
@ -481,7 +481,7 @@ fn finish_grow<A>(
new_layout: Result<Layout, LayoutErr>,
current_memory: Option<(NonNull<u8>, Layout)>,
alloc: &mut A,
) -> Result<MemoryBlock, TryReserveError>
) -> Result<NonNull<[u8]>, TryReserveError>
where
A: AllocRef,
{

2
library/alloc/src/raw_vec/tests.rs
View File

@ -20,7 +20,7 @@ fn allocator_param() {
fuel: usize,
}
unsafe impl AllocRef for BoundedAlloc {
fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
if size > self.fuel {
return Err(AllocErr);

4
library/alloc/src/rc.rs
View File

@ -928,10 +928,10 @@ impl<T: ?Sized> Rc<T> {
let layout = Layout::new::<RcBox<()>>().extend(value_layout).unwrap().0.pad_to_align();
// Allocate for the layout.
let mem = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
// Initialize the RcBox
let inner = mem_to_rcbox(mem.ptr.as_ptr());
let inner = mem_to_rcbox(ptr.as_non_null_ptr().as_ptr());
unsafe {
debug_assert_eq!(Layout::for_value(&*inner), layout);

6
library/alloc/src/sync.rs
View File

@ -883,10 +883,10 @@ impl<T: ?Sized> Arc<T> {
// reference (see #54908).
let layout = Layout::new::<ArcInner<()>>().extend(value_layout).unwrap().0.pad_to_align();
let mem = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
// Initialize the ArcInner
let inner = mem_to_arcinner(mem.ptr.as_ptr());
let inner = mem_to_arcinner(ptr.as_non_null_ptr().as_ptr());
debug_assert_eq!(unsafe { Layout::for_value(&*inner) }, layout);
unsafe {
@ -986,7 +986,7 @@ impl<T> Arc<[T]> {
let slice = from_raw_parts_mut(self.elems, self.n_elems);
ptr::drop_in_place(slice);
Global.dealloc(self.mem.cast(), self.layout);
Global.dealloc(self.mem, self.layout);
}
}
}

9
library/alloc/tests/heap.rs
View File

@ -20,12 +20,12 @@ fn check_overalign_requests<T: AllocRef>(mut allocator: T) {
unsafe {
let pointers: Vec<_> = (0..iterations)
.map(|_| {
allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap().ptr
allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap()
})
.collect();
for &ptr in &pointers {
assert_eq!(
(ptr.as_ptr() as usize) % align,
(ptr.as_non_null_ptr().as_ptr() as usize) % align,
0,
"Got a pointer less aligned than requested"
)
@ -33,7 +33,10 @@ fn check_overalign_requests<T: AllocRef>(mut allocator: T) {
// Clean up
for &ptr in &pointers {
allocator.dealloc(ptr, Layout::from_size_align(size, align).unwrap())
allocator.dealloc(
ptr.as_non_null_ptr(),
Layout::from_size_align(size, align).unwrap(),
)
}
}
}

1
library/alloc/tests/lib.rs
View File

@ -13,6 +13,7 @@
#![feature(associated_type_bounds)]
#![feature(binary_heap_into_iter_sorted)]
#![feature(binary_heap_drain_sorted)]
#![feature(slice_ptr_get)]
#![feature(split_inclusive)]
#![feature(binary_heap_retain)]

140
library/core/src/alloc/mod.rs
View File

@ -29,14 +29,6 @@ impl fmt::Display for AllocErr {
}
}
/// Represents a block of allocated memory returned by an allocator.
#[derive(Debug, Copy, Clone)]
#[unstable(feature = "allocator_api", issue = "32838")]
pub struct MemoryBlock {
pub ptr: NonNull<u8>,
pub size: usize,
}
/// An implementation of `AllocRef` can allocate, grow, shrink, and deallocate arbitrary blocks of
/// data described via [`Layout`][].
///
@ -50,13 +42,13 @@ pub struct MemoryBlock {
///
/// ### Currently allocated memory
///
/// Some of the methods require that a memory block be *currently allocated* via an allocator. This
/// Some of the methods require that a memory slice be *currently allocated* via an allocator. This
/// means that:
///
/// * the starting address for that memory block was previously returned by [`alloc`], [`grow`], or
/// * the starting address for that memory slice was previously returned by [`alloc`], [`grow`], or
/// [`shrink`], and
///
/// * the memory block has not been subsequently deallocated, where blocks are either deallocated
/// * the memory slice has not been subsequently deallocated, where slices are either deallocated
/// directly by being passed to [`dealloc`] or were changed by being passed to [`grow`] or
/// [`shrink`] that returns `Ok`. If `grow` or `shrink` have returned `Err`, the passed pointer
/// remains valid.
@ -68,14 +60,14 @@ pub struct MemoryBlock {
///
/// ### Memory fitting
///
/// Some of the methods require that a layout *fit* a memory block. What it means for a layout to
/// "fit" a memory block means (or equivalently, for a memory block to "fit" a layout) is that the
/// Some of the methods require that a layout *fit* a memory slice. What it means for a layout to
/// "fit" a memory slice means (or equivalently, for a memory slice to "fit" a layout) is that the
/// following conditions must hold:
///
/// * The block must be allocated with the same alignment as [`layout.align()`], and
/// * The slice must be allocated with the same alignment as [`layout.align()`], and
///
/// * The provided [`layout.size()`] must fall in the range `min ..= max`, where:
/// - `min` is the size of the layout most recently used to allocate the block, and
/// - `min` is the size of the layout most recently used to allocate the slice, and
/// - `max` is the latest actual size returned from [`alloc`], [`grow`], or [`shrink`].
///
/// [`layout.align()`]: Layout::align
@ -83,25 +75,27 @@ pub struct MemoryBlock {
///
/// # Safety
///
/// * Memory blocks returned from an allocator must point to valid memory and retain their validity
/// * Memory slices returned from an allocator must point to valid memory and retain their validity
/// until the instance and all of its clones are dropped,
///
/// * cloning or moving the allocator must not invalidate memory blocks returned from this
/// * cloning or moving the allocator must not invalidate memory slices returned from this
/// allocator. A cloned allocator must behave like the same allocator, and
///
/// * any pointer to a memory block which is [*currently allocated*] may be passed to any other
/// * any pointer to a memory slice which is [*currently allocated*] may be passed to any other
/// method of the allocator.
///
/// [*currently allocated*]: #currently-allocated-memory
#[unstable(feature = "allocator_api", issue = "32838")]
pub unsafe trait AllocRef {
/// Attempts to allocate a block of memory.
/// Attempts to allocate a slice of memory.
///
/// On success, returns a [`MemoryBlock`][] meeting the size and alignment guarantees of `layout`.
/// On success, returns a [`NonNull<[u8]>`] meeting the size and alignment guarantees of `layout`.
///
/// The returned block may have a larger size than specified by `layout.size()`, and may or may
/// The returned slice may have a larger size than specified by `layout.size()`, and may or may
/// not have its contents initialized.
///
/// [`NonNull<[u8]>`]: NonNull
///
/// # Errors
///
/// Returning `Err` indicates that either memory is exhausted or `layout` does not meet
@ -115,7 +109,7 @@ pub unsafe trait AllocRef {
/// call the [`handle_alloc_error`] function, rather than directly invoking `panic!` or similar.
///
/// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr>;
fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr>;
/// Behaves like `alloc`, but also ensures that the returned memory is zero-initialized.
///
@ -132,27 +126,27 @@ pub unsafe trait AllocRef {
/// call the [`handle_alloc_error`] function, rather than directly invoking `panic!` or similar.
///
/// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
fn alloc_zeroed(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
let memory = self.alloc(layout)?;
// SAFETY: `alloc` returns a valid memory block
unsafe { memory.ptr.as_ptr().write_bytes(0, memory.size) }
Ok(memory)
fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let ptr = self.alloc(layout)?;
// SAFETY: `alloc` returns a valid memory slice
unsafe { ptr.as_non_null_ptr().as_ptr().write_bytes(0, ptr.len()) }
Ok(ptr)
}
/// Deallocates the memory referenced by `ptr`.
/// Deallocates the memory slice referenced by `ptr`.
///
/// # Safety
///
/// * `ptr` must denote a block of memory [*currently allocated*] via this allocator, and
/// * `layout` must [*fit*] that block of memory.
/// * `ptr` must denote a slice of memory [*currently allocated*] via this allocator, and
/// * `layout` must [*fit*] that slice of memory.
///
/// [*currently allocated*]: #currently-allocated-memory
/// [*fit*]: #memory-fitting
unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout);
/// Attempts to extend the memory block.
/// Attempts to extend the memory slice.
///
/// Returns a new [`MemoryBlock`][] containing a pointer and the actual size of the allocated
/// Returns a new [`NonNull<[u8]>`] containing a pointer and the actual size of the allocated
/// memory. The pointer is suitable for holding data described by a new layout with `layout`’s
/// alignment and a size given by `new_size`. To accomplish this, the allocator may extend the
/// allocation referenced by `ptr` to fit the new layout.
@ -160,6 +154,8 @@ pub unsafe trait AllocRef {
/// If this method returns `Err`, then ownership of the memory block has not been transferred to
/// this allocator, and the contents of the memory block are unaltered.
///
/// [`NonNull<[u8]>`]: NonNull
///
/// # Safety
///
/// * `ptr` must denote a block of memory [*currently allocated*] via this allocator,
@ -168,7 +164,7 @@ pub unsafe trait AllocRef {
/// * `new_size`, when rounded up to the nearest multiple of `layout.align()`, must not overflow
/// (i.e., the rounded value must be less than or equal to `usize::MAX`).
// Note: We can't require that `new_size` is strictly greater than `layout.size()` because of ZSTs.
// alternative: `new_size must be strictly greater than `layout.size()` or both are zero
// alternative: `new_size` must be strictly greater than `layout.size()` or both are zero
///
/// [*currently allocated*]: #currently-allocated-memory
/// [*fit*]: #memory-fitting
@ -191,15 +187,15 @@ pub unsafe trait AllocRef {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
debug_assert!(
new_size >= size,
"`new_size` must be greater than or equal to `layout.size()`"
);
if new_size == size {
return Ok(MemoryBlock { ptr, size });
if size == new_size {
return Ok(NonNull::slice_from_raw_parts(ptr, size));
}
let new_layout =
@ -208,17 +204,17 @@ pub unsafe trait AllocRef {
// The caller must ensure that `new_size` is greater than or equal to zero. If it's equal
// to zero, it's catched beforehand.
unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
let new_memory = self.alloc(new_layout)?;
let new_ptr = self.alloc(new_layout)?;
// SAFETY: because `new_size` must be greater than or equal to `size`, both the old and new
// memory allocation are valid for reads and writes for `size` bytes. Also, because the old
// allocation wasn't yet deallocated, it cannot overlap `new_memory`. Thus, the call to
// allocation wasn't yet deallocated, it cannot overlap `new_ptr`. Thus, the call to
// `copy_nonoverlapping` is safe.
// The safety contract for `dealloc` must be upheld by the caller.
unsafe {
ptr::copy_nonoverlapping(ptr.as_ptr(), new_memory.ptr.as_ptr(), size);
ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_non_null_ptr().as_ptr(), size);
self.dealloc(ptr, layout);
Ok(new_memory)
Ok(new_ptr)
}
}
@ -239,12 +235,11 @@ pub unsafe trait AllocRef {
///
/// * `ptr` must denote a block of memory [*currently allocated*] via this allocator,
/// * `layout` must [*fit*] that block of memory (The `new_size` argument need not fit it.),
// We can't require that `new_size` is strictly greater than `memory.size` because of ZSTs.
// An alternative would be
// * `new_size must be strictly greater than `memory.size` or both are zero
/// * `new_size` must be greater than or equal to `layout.size()`, and
/// * `new_size`, when rounded up to the nearest multiple of `layout.align()`, must not overflow
/// (i.e., the rounded value must be less than or equal to `usize::MAX`).
// Note: We can't require that `new_size` is strictly greater than `layout.size()` because of ZSTs.
// alternative: `new_size` must be strictly greater than `layout.size()` or both are zero
///
/// [*currently allocated*]: #currently-allocated-memory
/// [*fit*]: #memory-fitting
@ -267,15 +262,15 @@ pub unsafe trait AllocRef {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
debug_assert!(
new_size >= size,
"`new_size` must be greater than or equal to `layout.size()`"
);
if new_size == size {
return Ok(MemoryBlock { ptr, size });
if size == new_size {
return Ok(NonNull::slice_from_raw_parts(ptr, size));
}
let new_layout =
@ -284,43 +279,44 @@ pub unsafe trait AllocRef {
// The caller must ensure that `new_size` is greater than or equal to zero. If it's equal
// to zero, it's caught beforehand.
unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
let new_memory = self.alloc_zeroed(new_layout)?;
let new_ptr = self.alloc_zeroed(new_layout)?;
// SAFETY: because `new_size` must be greater than or equal to `size`, both the old and new
// memory allocation are valid for reads and writes for `size` bytes. Also, because the old
// allocation wasn't yet deallocated, it cannot overlap `new_memory`. Thus, the call to
// allocation wasn't yet deallocated, it cannot overlap `new_ptr`. Thus, the call to
// `copy_nonoverlapping` is safe.
// The safety contract for `dealloc` must be upheld by the caller.
unsafe {
ptr::copy_nonoverlapping(ptr.as_ptr(), new_memory.ptr.as_ptr(), size);
ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_non_null_ptr().as_ptr(), size);
self.dealloc(ptr, layout);
Ok(new_memory)
Ok(new_ptr)
}
}
/// Attempts to shrink the memory block.
/// Attempts to shrink the memory slice.
///
/// Returns a new [`MemoryBlock`][] containing a pointer and the actual size of the allocated
/// Returns a new [`NonNull<[u8]>`] containing a pointer and the actual size of the allocated
/// memory. The pointer is suitable for holding data described by a new layout with `layout`’s
/// alignment and a size given by `new_size`. To accomplish this, the allocator may shrink the
/// allocation referenced by `ptr` to fit the new layout.
///
/// If this returns `Ok`, then ownership of the memory block referenced by `ptr` has been
/// If this returns `Ok`, then ownership of the memory slice referenced by `ptr` has been
/// transferred to this allocator. The memory may or may not have been freed, and should be
/// considered unusable unless it was transferred back to the caller again via the
/// return value of this method.
///
/// If this method returns `Err`, then ownership of the memory block has not been transferred to
/// this allocator, and the contents of the memory block are unaltered.
/// If this method returns `Err`, then ownership of the memory slice has not been transferred to
/// this allocator, and the contents of the memory slice are unaltered.
///
/// [`NonNull<[u8]>`]: NonNull
///
/// # Safety
///
/// * `ptr` must denote a block of memory [*currently allocated*] via this allocator,
/// * `layout` must [*fit*] that block of memory (The `new_size` argument need not fit it.), and
// We can't require that `new_size` is strictly smaller than `memory.size` because of ZSTs.
// An alternative would be
// * `new_size must be strictly smaller than `memory.size` or both are zero
/// * `ptr` must denote a slice of memory [*currently allocated*] via this allocator,
/// * `layout` must [*fit*] that slice of memory (The `new_size` argument need not fit it.), and
/// * `new_size` must be smaller than or equal to `layout.size()`.
// Note: We can't require that `new_size` is strictly smaller than `layout.size()` because of ZSTs.
// alternative: `new_size` must be smaller than `layout.size()` or both are zero
///
/// [*currently allocated*]: #currently-allocated-memory
/// [*fit*]: #memory-fitting
@ -343,15 +339,15 @@ pub unsafe trait AllocRef {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
debug_assert!(
new_size <= size,
"`new_size` must be smaller than or equal to `layout.size()`"
);
if new_size == size {
return Ok(MemoryBlock { ptr, size });
if size == new_size {
return Ok(NonNull::slice_from_raw_parts(ptr, size));
}
let new_layout =
@ -359,17 +355,17 @@ pub unsafe trait AllocRef {
// `layout.align()` comes from a `Layout` and is thus guaranteed to be valid for a Layout.
// The caller must ensure that `new_size` is greater than zero.
unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
let new_memory = self.alloc(new_layout)?;
let new_ptr = self.alloc(new_layout)?;
// SAFETY: because `new_size` must be lower than or equal to `size`, both the old and new
// memory allocation are valid for reads and writes for `new_size` bytes. Also, because the
// old allocation wasn't yet deallocated, it cannot overlap `new_memory`. Thus, the call to
// old allocation wasn't yet deallocated, it cannot overlap `new_ptr`. Thus, the call to
// `copy_nonoverlapping` is safe.
// The safety contract for `dealloc` must be upheld by the caller.
unsafe {
ptr::copy_nonoverlapping(ptr.as_ptr(), new_memory.ptr.as_ptr(), new_size);
ptr::copy_nonoverlapping(ptr.as_ptr(), new_ptr.as_non_null_ptr().as_ptr(), size);
self.dealloc(ptr, layout);
Ok(new_memory)
Ok(new_ptr)
}
}
@ -388,12 +384,12 @@ where
A: AllocRef + ?Sized,
{
#[inline]
fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
(**self).alloc(layout)
}
#[inline]
fn alloc_zeroed(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
(**self).alloc_zeroed(layout)
}
@ -409,7 +405,7 @@ where
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
// SAFETY: the safety contract must be upheld by the caller
unsafe { (**self).grow(ptr, layout, new_size) }
}
@ -420,7 +416,7 @@ where
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
// SAFETY: the safety contract must be upheld by the caller
unsafe { (**self).grow_zeroed(ptr, layout, new_size) }
}
@ -431,7 +427,7 @@ where
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
// SAFETY: the safety contract must be upheld by the caller
unsafe { (**self).shrink(ptr, layout, new_size) }
}

28
library/std/src/alloc.rs
View File

@ -140,7 +140,7 @@ pub struct System;
#[unstable(feature = "allocator_api", issue = "32838")]
unsafe impl AllocRef for System {
#[inline]
fn alloc(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
let ptr = if size == 0 {
layout.dangling()
@ -148,11 +148,11 @@ unsafe impl AllocRef for System {
// SAFETY: `layout` is non-zero in size,
unsafe { NonNull::new(GlobalAlloc::alloc(&System, layout)).ok_or(AllocErr)? }
};
Ok(MemoryBlock { ptr, size })
Ok(NonNull::slice_from_raw_parts(ptr, size))
}
#[inline]
fn alloc_zeroed(&mut self, layout: Layout) -> Result<MemoryBlock, AllocErr> {
fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
let size = layout.size();
let ptr = if size == 0 {
layout.dangling()
@ -160,7 +160,7 @@ unsafe impl AllocRef for System {
// SAFETY: `layout` is non-zero in size,
unsafe { NonNull::new(GlobalAlloc::alloc_zeroed(&System, layout)).ok_or(AllocErr)? }
};
Ok(MemoryBlock { ptr, size })
Ok(NonNull::slice_from_raw_parts(ptr, size))
}
#[inline]
@ -178,7 +178,7 @@ unsafe impl AllocRef for System {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
debug_assert!(
new_size >= layout.size(),
"`new_size` must be greater than or equal to `layout.size()`"
@ -188,14 +188,16 @@ unsafe impl AllocRef for System {
// Other conditions must be upheld by the caller
unsafe {
match layout.size() {
old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
old_size if old_size == new_size => {
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
0 => self.alloc(Layout::from_size_align_unchecked(new_size, layout.align())),
old_size => {
// `realloc` probably checks for `new_size > size` or something similar.
intrinsics::assume(new_size > old_size);
let raw_ptr = GlobalAlloc::realloc(&System, ptr.as_ptr(), layout, new_size);
let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
}
@ -207,7 +209,7 @@ unsafe impl AllocRef for System {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
debug_assert!(
new_size >= layout.size(),
"`new_size` must be greater than or equal to `layout.size()`"
@ -217,7 +219,9 @@ unsafe impl AllocRef for System {
// Other conditions must be upheld by the caller
unsafe {
match layout.size() {
old_size if old_size == new_size => Ok(MemoryBlock { ptr, size: new_size }),
old_size if old_size == new_size => {
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
0 => self.alloc_zeroed(Layout::from_size_align_unchecked(new_size, layout.align())),
old_size => {
// `realloc` probably checks for `new_size > size` or something similar.
@ -225,7 +229,7 @@ unsafe impl AllocRef for System {
let raw_ptr = GlobalAlloc::realloc(&System, ptr.as_ptr(), layout, new_size);
raw_ptr.add(old_size).write_bytes(0, new_size - old_size);
let ptr = NonNull::new(raw_ptr).ok_or(AllocErr)?;
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
}
@ -237,7 +241,7 @@ unsafe impl AllocRef for System {
ptr: NonNull<u8>,
layout: Layout,
new_size: usize,
) -> Result<MemoryBlock, AllocErr> {
) -> Result<NonNull<[u8]>, AllocErr> {
let old_size = layout.size();
debug_assert!(
new_size <= old_size,
@ -264,7 +268,7 @@ unsafe impl AllocRef for System {
NonNull::new(raw_ptr).ok_or(AllocErr)?
};
Ok(MemoryBlock { ptr, size: new_size })
Ok(NonNull::slice_from_raw_parts(ptr, new_size))
}
}
static HOOK: AtomicPtr<()> = AtomicPtr::new(ptr::null_mut());

3
library/std/src/lib.rs
View File

@ -291,6 +291,7 @@
#![feature(negative_impls)]
#![feature(never_type)]
#![feature(nll)]
#![feature(nonnull_slice_from_raw_parts)]
#![feature(once_cell)]
#![feature(optin_builtin_traits)]
#![feature(or_patterns)]
@ -308,6 +309,8 @@
#![feature(shrink_to)]
#![feature(slice_concat_ext)]
#![feature(slice_internals)]
#![feature(slice_ptr_get)]
#![feature(slice_ptr_len)]
#![feature(slice_strip)]
#![feature(staged_api)]
#![feature(std_internals)]

9
src/test/ui/allocator/custom.rs
View File

@ -4,6 +4,7 @@
// no-prefer-dynamic
#![feature(allocator_api)]
#![feature(slice_ptr_get)]
extern crate helper;
@ -38,9 +39,9 @@ fn main() {
let layout = Layout::from_size_align(4, 2).unwrap();
let memory = Global.alloc(layout.clone()).unwrap();
helper::work_with(&memory.ptr);
helper::work_with(&memory);
assert_eq!(HITS.load(Ordering::SeqCst), n + 1);
Global.dealloc(memory.ptr, layout);
Global.dealloc(memory.as_non_null_ptr(), layout);
assert_eq!(HITS.load(Ordering::SeqCst), n + 2);
let s = String::with_capacity(10);
@ -51,8 +52,8 @@ fn main() {
let memory = System.alloc(layout.clone()).unwrap();
assert_eq!(HITS.load(Ordering::SeqCst), n + 4);
helper::work_with(&memory.ptr);
System.dealloc(memory.ptr, layout);
helper::work_with(&memory);
System.dealloc(memory.as_non_null_ptr(), layout);
assert_eq!(HITS.load(Ordering::SeqCst), n + 4);
}
}

9
src/test/ui/allocator/xcrate-use.rs
View File

@ -5,6 +5,7 @@
// no-prefer-dynamic
#![feature(allocator_api)]
#![feature(slice_ptr_get)]
extern crate custom;
extern crate helper;
@ -21,15 +22,15 @@ fn main() {
let layout = Layout::from_size_align(4, 2).unwrap();
let memory = Global.alloc(layout.clone()).unwrap();
helper::work_with(&memory.ptr);
helper::work_with(&memory);
assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 1);
Global.dealloc(memory.ptr, layout);
Global.dealloc(memory.as_non_null_ptr(), layout);
assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
let memory = System.alloc(layout.clone()).unwrap();
assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
helper::work_with(&memory.ptr);
System.dealloc(memory.ptr, layout);
helper::work_with(&memory);
System.dealloc(memory.as_non_null_ptr(), layout);
assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
}
}

13
src/test/ui/realloc-16687.rs
View File

@ -5,6 +5,7 @@
// well enough to reproduce (and illustrate) the bug from #16687.
#![feature(allocator_api)]
#![feature(slice_ptr_get)]
use std::alloc::{handle_alloc_error, AllocRef, Global, Layout};
use std::ptr::{self, NonNull};
@ -41,13 +42,13 @@ unsafe fn test_triangle() -> bool {
println!("allocate({:?})", layout);
}
let memory = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
if PRINT {
println!("allocate({:?}) = {:?}", layout, memory.ptr);
println!("allocate({:?}) = {:?}", layout, ptr);
}
memory.ptr.cast().as_ptr()
ptr.as_non_null_ptr().as_ptr()
}
unsafe fn deallocate(ptr: *mut u8, layout: Layout) {
@ -73,14 +74,14 @@ unsafe fn test_triangle() -> bool {
Global.shrink(NonNull::new_unchecked(ptr), old, new.size())
};
let memory = memory.unwrap_or_else(|_| {
let ptr = memory.unwrap_or_else(|_| {
handle_alloc_error(Layout::from_size_align_unchecked(new.size(), old.align()))
});
if PRINT {
println!("reallocate({:?}, old={:?}, new={:?}) = {:?}", ptr, old, new, memory.ptr);
println!("reallocate({:?}, old={:?}, new={:?}) = {:?}", ptr, old, new, ptr);
}
memory.ptr.cast().as_ptr()
ptr.as_non_null_ptr().as_ptr()
}
fn idx_to_size(i: usize) -> usize {

4
src/test/ui/regions/regions-mock-codegen.rs
View File

@ -25,8 +25,8 @@ struct Ccx {
fn alloc(_bcx: &arena) -> &Bcx<'_> {
unsafe {
let layout = Layout::new::<Bcx>();
let memory = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
&*(memory.ptr.as_ptr() as *const _)
let ptr = Global.alloc(layout).unwrap_or_else(|_| handle_alloc_error(layout));
&*(ptr.as_ptr() as *const _)
}
}