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Use alloc::Layout in DroplessArena API

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This commit is contained in:
Tomasz Miąsko 2020-06-17 00:00:00 +00:00
parent 2935d294ff
commit f488dfc2b6
2 changed files with 24 additions and 32 deletions
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39
src/librustc_arena/lib.rs
View File

@ -22,6 +22,7 @@
use rustc_data_structures::cold_path;
use smallvec::SmallVec;
use std::alloc::Layout;
use std::cell::{Cell, RefCell};
use std::cmp;
use std::intrinsics;
@ -363,13 +364,15 @@ fn grow(&self, additional: usize) {
}
}
/// Allocates a byte slice with specified size and alignment from the
/// current memory chunk. Returns `None` if there is no free space left to
/// satisfy the request.
/// Allocates a byte slice with specified layout from the current memory
/// chunk. Returns `None` if there is no free space left to satisfy the
/// request.
#[inline]
fn alloc_raw_without_grow(&self, bytes: usize, align: usize) -> Option<*mut u8> {
fn alloc_raw_without_grow(&self, layout: Layout) -> Option<*mut u8> {
let ptr = self.ptr.get() as usize;
let end = self.end.get() as usize;
let align = layout.align();
let bytes = layout.size();
// The allocation request fits into the current chunk iff:
//
// let aligned = align_to(ptr, align);
@ -390,15 +393,15 @@ fn alloc_raw_without_grow(&self, bytes: usize, align: usize) -> Option<*mut u8>
}
#[inline]
pub fn alloc_raw(&self, bytes: usize, align: usize) -> *mut u8 {
assert!(bytes != 0);
pub fn alloc_raw(&self, layout: Layout) -> *mut u8 {
assert!(layout.size() != 0);
loop {
if let Some(a) = self.alloc_raw_without_grow(bytes, align) {
if let Some(a) = self.alloc_raw_without_grow(layout) {
break a;
}
// No free space left. Allocate a new chunk to satisfy the request.
// On failure the grow will panic or abort.
self.grow(bytes);
self.grow(layout.size());
}
}
@ -406,7 +409,7 @@ pub fn alloc_raw(&self, bytes: usize, align: usize) -> *mut u8 {
pub fn alloc<T>(&self, object: T) -> &mut T {
assert!(!mem::needs_drop::<T>());
let mem = self.alloc_raw(mem::size_of::<T>(), mem::align_of::<T>()) as *mut T;
let mem = self.alloc_raw(Layout::for_value::<T>(&object)) as *mut T;
unsafe {
// Write into uninitialized memory.
@ -431,7 +434,7 @@ pub fn alloc_slice<T>(&self, slice: &[T]) -> &mut [T]
assert!(mem::size_of::<T>() != 0);
assert!(!slice.is_empty());
let mem = self.alloc_raw(slice.len() * mem::size_of::<T>(), mem::align_of::<T>()) as *mut T;
let mem = self.alloc_raw(Layout::for_value::<[T]>(slice)) as *mut T;
unsafe {
mem.copy_from_nonoverlapping(slice.as_ptr(), slice.len());
@ -477,8 +480,8 @@ pub fn alloc_from_iter<T, I: IntoIterator<Item = T>>(&self, iter: I) -> &mut [T]
if len == 0 {
return &mut [];
}
let size = len.checked_mul(mem::size_of::<T>()).unwrap();
let mem = self.alloc_raw(size, mem::align_of::<T>()) as *mut T;
let mem = self.alloc_raw(Layout::array::<T>(len).unwrap()) as *mut T;
unsafe { self.write_from_iter(iter, len, mem) }
}
(_, _) => {
@ -491,9 +494,8 @@ pub fn alloc_from_iter<T, I: IntoIterator<Item = T>>(&self, iter: I) -> &mut [T]
// the content of the SmallVec
unsafe {
let len = vec.len();
let start_ptr = self
.alloc_raw(len * mem::size_of::<T>(), mem::align_of::<T>())
as *mut T;
let start_ptr =
self.alloc_raw(Layout::for_value::<[T]>(vec.as_slice())) as *mut T;
vec.as_ptr().copy_to_nonoverlapping(start_ptr, len);
vec.set_len(0);
slice::from_raw_parts_mut(start_ptr, len)
@ -537,7 +539,7 @@ pub struct DropArena {
impl DropArena {
#[inline]
pub unsafe fn alloc<T>(&self, object: T) -> &mut T {
let mem = self.arena.alloc_raw(mem::size_of::<T>(), mem::align_of::<T>()) as *mut T;
let mem = self.arena.alloc_raw(Layout::new::<T>()) as *mut T;
// Write into uninitialized memory.
ptr::write(mem, object);
let result = &mut *mem;
@ -557,10 +559,7 @@ pub unsafe fn alloc_from_iter<T, I: IntoIterator<Item = T>>(&self, iter: I) -> &
}
let len = vec.len();
let start_ptr = self
.arena
.alloc_raw(len.checked_mul(mem::size_of::<T>()).unwrap(), mem::align_of::<T>())
as *mut T;
let start_ptr = self.arena.alloc_raw(Layout::array::<T>(len).unwrap()) as *mut T;
let mut destructors = self.destructors.borrow_mut();
// Reserve space for the destructors so we can't panic while adding them

17
src/librustc_middle/ty/list.rs
View File

@ -2,7 +2,8 @@
use rustc_serialize::{Encodable, Encoder};
use std::cmp::{self, Ordering};
use std::alloc::Layout;
use std::cmp::Ordering;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::iter;
@ -43,17 +44,9 @@ pub(super) fn from_arena<'tcx>(arena: &'tcx Arena<'tcx>, slice: &[T]) -> &'tcx L
assert!(mem::size_of::<T>() != 0);
assert!(!slice.is_empty());
// Align up the size of the len (usize) field
let align = mem::align_of::<T>();
let align_mask = align - 1;
let offset = mem::size_of::<usize>();
let offset = (offset + align_mask) & !align_mask;
let size = offset + slice.len() * mem::size_of::<T>();
let mem = arena
.dropless
.alloc_raw(size, cmp::max(mem::align_of::<T>(), mem::align_of::<usize>()));
let (layout, _offset) =
Layout::new::<usize>().extend(Layout::for_value::<[T]>(slice)).unwrap();
let mem = arena.dropless.alloc_raw(layout);
unsafe {
let result = &mut *(mem as *mut List<T>);
// Write the length