1- #[ cfg( rayon_hash_unstable) ] pub use std:: alloc:: oom;
2- #[ cfg( not( rayon_hash_unstable) ) ] pub use std:: process:: abort as oom;
1+ // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2+ // file at the top-level directory of this distribution and at
3+ // http://rust-lang.org/COPYRIGHT.
4+ //
5+ // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+ // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+ // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+ // option. This file may not be copied, modified, or distributed
9+ // except according to those terms.
10+
11+ //! Memory allocation APIs (forked from `libcore/alloc.rs`)
12+
13+ // #![stable(feature = "alloc_module", since = "1.28.0")]
14+
15+ use std:: cmp;
16+ use std:: mem;
17+ use std:: usize;
18+ use std:: alloc:: { self , LayoutErr } ;
19+
20+ #[ inline]
21+ fn layout_err ( ) -> LayoutErr {
22+ alloc:: Layout :: from_size_align ( usize:: MAX , usize:: MAX ) . unwrap_err ( )
23+ }
24+
25+ /// Layout of a block of memory.
26+ ///
27+ /// An instance of `Layout` describes a particular layout of memory.
28+ /// You build a `Layout` up as an input to give to an allocator.
29+ ///
30+ /// All layouts have an associated non-negative size and a
31+ /// power-of-two alignment.
32+ ///
33+ /// (Note however that layouts are *not* required to have positive
34+ /// size, even though many allocators require that all memory
35+ /// requests have positive size. A caller to the `Alloc::alloc`
36+ /// method must either ensure that conditions like this are met, or
37+ /// use specific allocators with looser requirements.)
38+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
39+ #[ derive( Copy , Clone , Debug , PartialEq , Eq ) ]
40+ pub ( crate ) struct Layout {
41+ inner : alloc:: Layout ,
42+ }
43+
44+ impl Layout {
45+ /// Constructs a `Layout` from a given `size` and `align`,
46+ /// or returns `LayoutErr` if either of the following conditions
47+ /// are not met:
48+ ///
49+ /// * `align` must be a power of two,
50+ ///
51+ /// * `size`, when rounded up to the nearest multiple of `align`,
52+ /// must not overflow (i.e. the rounded value must be less than
53+ /// `usize::MAX`).
54+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
55+ #[ inline]
56+ pub ( crate ) fn from_size_align ( size : usize , align : usize ) -> Result < Self , LayoutErr > {
57+ alloc:: Layout :: from_size_align ( size, align) . map ( Layout :: from)
58+ }
59+
60+ /// Creates a layout, bypassing all checks.
61+ ///
62+ /// # Safety
63+ ///
64+ /// This function is unsafe as it does not verify the preconditions from
65+ /// [`Layout::from_size_align`](#method.from_size_align).
66+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
67+ #[ inline]
68+ pub ( crate ) unsafe fn from_size_align_unchecked ( size : usize , align : usize ) -> Self {
69+ Layout :: from ( alloc:: Layout :: from_size_align_unchecked ( size, align) )
70+ }
71+
72+ /// The minimum size in bytes for a memory block of this layout.
73+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
74+ #[ inline]
75+ pub ( crate ) fn size ( & self ) -> usize { self . inner . size ( ) }
76+
77+ /// The minimum byte alignment for a memory block of this layout.
78+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
79+ #[ inline]
80+ pub ( crate ) fn align ( & self ) -> usize { self . inner . align ( ) }
81+
82+ /// Constructs a `Layout` suitable for holding a value of type `T`.
83+ // #[stable(feature = "alloc_layout", since = "1.28.0")]
84+ #[ inline]
85+ pub ( crate ) fn new < T > ( ) -> Self {
86+ Layout :: from ( alloc:: Layout :: new :: < T > ( ) )
87+ }
88+
89+ /// Returns the amount of padding we must insert after `self`
90+ /// to ensure that the following address will satisfy `align`
91+ /// (measured in bytes).
92+ ///
93+ /// E.g. if `self.size()` is 9, then `self.padding_needed_for(4)`
94+ /// returns 3, because that is the minimum number of bytes of
95+ /// padding required to get a 4-aligned address (assuming that the
96+ /// corresponding memory block starts at a 4-aligned address).
97+ ///
98+ /// The return value of this function has no meaning if `align` is
99+ /// not a power-of-two.
100+ ///
101+ /// Note that the utility of the returned value requires `align`
102+ /// to be less than or equal to the alignment of the starting
103+ /// address for the whole allocated block of memory. One way to
104+ /// satisfy this constraint is to ensure `align <= self.align()`.
105+ // #[unstable(feature = "allocator_api", issue = "32838")]
106+ #[ inline]
107+ pub ( crate ) fn padding_needed_for ( & self , align : usize ) -> usize {
108+ let len = self . size ( ) ;
109+
110+ // Rounded up value is:
111+ // len_rounded_up = (len + align - 1) & !(align - 1);
112+ // and then we return the padding difference: `len_rounded_up - len`.
113+ //
114+ // We use modular arithmetic throughout:
115+ //
116+ // 1. align is guaranteed to be > 0, so align - 1 is always
117+ // valid.
118+ //
119+ // 2. `len + align - 1` can overflow by at most `align - 1`,
120+ // so the &-mask wth `!(align - 1)` will ensure that in the
121+ // case of overflow, `len_rounded_up` will itself be 0.
122+ // Thus the returned padding, when added to `len`, yields 0,
123+ // which trivially satisfies the alignment `align`.
124+ //
125+ // (Of course, attempts to allocate blocks of memory whose
126+ // size and padding overflow in the above manner should cause
127+ // the allocator to yield an error anyway.)
128+
129+ let len_rounded_up = len. wrapping_add ( align) . wrapping_sub ( 1 )
130+ & !align. wrapping_sub ( 1 ) ;
131+ return len_rounded_up. wrapping_sub ( len) ;
132+ }
133+
134+ /// Creates a layout describing the record for `n` instances of
135+ /// `self`, with a suitable amount of padding between each to
136+ /// ensure that each instance is given its requested size and
137+ /// alignment. On success, returns `(k, offs)` where `k` is the
138+ /// layout of the array and `offs` is the distance between the start
139+ /// of each element in the array.
140+ ///
141+ /// On arithmetic overflow, returns `LayoutErr`.
142+ // #[unstable(feature = "allocator_api", issue = "32838")]
143+ #[ inline]
144+ pub ( crate ) fn repeat ( & self , n : usize ) -> Result < ( Self , usize ) , LayoutErr > {
145+ let padded_size = self . size ( ) . checked_add ( self . padding_needed_for ( self . align ( ) ) )
146+ . ok_or ( layout_err ( ) ) ?;
147+ let alloc_size = padded_size. checked_mul ( n)
148+ . ok_or ( layout_err ( ) ) ?;
149+
150+ unsafe {
151+ // self.align is already known to be valid and alloc_size has been
152+ // padded already.
153+ Ok ( ( Layout :: from_size_align_unchecked ( alloc_size, self . align ( ) ) , padded_size) )
154+ }
155+ }
156+
157+ /// Creates a layout describing the record for `self` followed by
158+ /// `next`, including any necessary padding to ensure that `next`
159+ /// will be properly aligned. Note that the result layout will
160+ /// satisfy the alignment properties of both `self` and `next`.
161+ ///
162+ /// Returns `Some((k, offset))`, where `k` is layout of the concatenated
163+ /// record and `offset` is the relative location, in bytes, of the
164+ /// start of the `next` embedded within the concatenated record
165+ /// (assuming that the record itself starts at offset 0).
166+ ///
167+ /// On arithmetic overflow, returns `LayoutErr`.
168+ // #[unstable(feature = "allocator_api", issue = "32838")]
169+ #[ inline]
170+ pub ( crate ) fn extend ( & self , next : Self ) -> Result < ( Self , usize ) , LayoutErr > {
171+ let new_align = cmp:: max ( self . align ( ) , next. align ( ) ) ;
172+ let pad = self . padding_needed_for ( next. align ( ) ) ;
173+
174+ let offset = self . size ( ) . checked_add ( pad)
175+ . ok_or ( layout_err ( ) ) ?;
176+ let new_size = offset. checked_add ( next. size ( ) )
177+ . ok_or ( layout_err ( ) ) ?;
178+
179+ let layout = Layout :: from_size_align ( new_size, new_align) ?;
180+ Ok ( ( layout, offset) )
181+ }
182+
183+ /// Creates a layout describing the record for a `[T; n]`.
184+ ///
185+ /// On arithmetic overflow, returns `LayoutErr`.
186+ // #[unstable(feature = "allocator_api", issue = "32838")]
187+ #[ inline]
188+ pub ( crate ) fn array < T > ( n : usize ) -> Result < Self , LayoutErr > {
189+ Layout :: new :: < T > ( )
190+ . repeat ( n)
191+ . map ( |( k, offs) | {
192+ debug_assert ! ( offs == mem:: size_of:: <T >( ) ) ;
193+ k
194+ } )
195+ }
196+ }
197+
198+ impl From < alloc:: Layout > for Layout {
199+ #[ inline]
200+ fn from ( inner : alloc:: Layout ) -> Layout {
201+ Layout { inner }
202+ }
203+ }
204+
205+ impl From < Layout > for alloc:: Layout {
206+ #[ inline]
207+ fn from ( layout : Layout ) -> alloc:: Layout {
208+ layout. inner
209+ }
210+ }
3211
4212/// Augments `AllocErr` with a CapacityOverflow variant.
213+ // FIXME: should this be in libcore or liballoc?
5214#[ derive( Clone , PartialEq , Eq , Debug ) ]
6215// #[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
7216pub enum CollectionAllocErr {
@@ -11,3 +220,11 @@ pub enum CollectionAllocErr {
11220 /// Error due to the allocator (see the `AllocErr` type's docs).
12221AllocErr ,
13222}
223+
224+ // #[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
225+ impl From < LayoutErr > for CollectionAllocErr {
226+ #[ inline]
227+ fn from ( _: LayoutErr ) -> Self {
228+ CollectionAllocErr :: CapacityOverflow
229+ }
230+ }
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