1 use arena::{TypedArena, DroplessArena};
5 use std::cell::RefCell;
6 use std::marker::PhantomData;
7 use smallvec::SmallVec;
10 macro_rules! arena_types {
11 ($macro:path, $args:tt, $tcx:lifetime) => (
13 [] vtable_method: Option<(
14 rustc::hir::def_id::DefId,
15 rustc::ty::subst::SubstsRef<$tcx>
17 [few] mir_keys: rustc::util::nodemap::DefIdSet,
18 [decode] specialization_graph: rustc::traits::specialization_graph::Graph,
19 [] region_scope_tree: rustc::middle::region::ScopeTree,
20 [] item_local_set: rustc::util::nodemap::ItemLocalSet,
21 [decode] mir_const_qualif: rustc_data_structures::bit_set::BitSet<rustc::mir::Local>,
22 [] trait_impls_of: rustc::ty::trait_def::TraitImpls,
24 rustc::infer::canonical::Canonical<'tcx,
25 rustc::infer::canonical::QueryResponse<'tcx,
26 rustc::traits::query::dropck_outlives::DropckOutlivesResult<'tcx>
29 [] normalize_projection_ty:
30 rustc::infer::canonical::Canonical<'tcx,
31 rustc::infer::canonical::QueryResponse<'tcx,
32 rustc::traits::query::normalize::NormalizationResult<'tcx>
35 [] implied_outlives_bounds:
36 rustc::infer::canonical::Canonical<'tcx,
37 rustc::infer::canonical::QueryResponse<'tcx,
38 Vec<rustc::traits::query::outlives_bounds::OutlivesBound<'tcx>>
42 rustc::infer::canonical::Canonical<'tcx,
43 rustc::infer::canonical::QueryResponse<'tcx, ()>
45 [] type_op_normalize_poly_fn_sig:
46 rustc::infer::canonical::Canonical<'tcx,
47 rustc::infer::canonical::QueryResponse<'tcx, rustc::ty::PolyFnSig<'tcx>>
49 [] type_op_normalize_fn_sig:
50 rustc::infer::canonical::Canonical<'tcx,
51 rustc::infer::canonical::QueryResponse<'tcx, rustc::ty::FnSig<'tcx>>
53 [] type_op_normalize_predicate:
54 rustc::infer::canonical::Canonical<'tcx,
55 rustc::infer::canonical::QueryResponse<'tcx, rustc::ty::Predicate<'tcx>>
57 [] type_op_normalize_ty:
58 rustc::infer::canonical::Canonical<'tcx,
59 rustc::infer::canonical::QueryResponse<'tcx, rustc::ty::Ty<'tcx>>
61 [few] crate_inherent_impls: rustc::ty::CrateInherentImpls,
62 [decode] borrowck: rustc::middle::borrowck::BorrowCheckResult,
67 macro_rules! arena_for_type {
71 ([few $(, $attrs:ident)*][$ty:ty]) => {
74 ([$ignore:ident $(, $attrs:ident)*]$args:tt) => {
75 arena_for_type!([$($attrs),*]$args)
79 macro_rules! declare_arena {
80 ([], [$($a:tt $name:ident: $ty:ty,)*], $tcx:lifetime) => {
82 pub struct Arena<$tcx> {
83 dropless: DroplessArena,
85 $($name: arena_for_type!($a[$ty]),)*
90 macro_rules! which_arena_for_type {
91 ([][$arena:expr]) => {
94 ([few$(, $attrs:ident)*][$arena:expr]) => {
97 ([$ignore:ident$(, $attrs:ident)*]$args:tt) => {
98 which_arena_for_type!([$($attrs),*]$args)
102 macro_rules! impl_arena_allocatable {
103 ([], [$($a:tt $name:ident: $ty:ty,)*], $tcx:lifetime) => {
105 impl ArenaAllocatable for $ty {}
106 unsafe impl<$tcx> ArenaField<$tcx> for $ty {
108 fn arena<'a>(_arena: &'a Arena<$tcx>) -> Option<&'a TypedArena<Self>> {
109 which_arena_for_type!($a[&_arena.$name])
116 arena_types!(declare_arena, [], 'tcx);
118 arena_types!(impl_arena_allocatable, [], 'tcx);
120 pub trait ArenaAllocatable {}
122 impl<T: Copy> ArenaAllocatable for T {}
124 pub unsafe trait ArenaField<'tcx>: Sized {
125 /// Returns a specific arena to allocate from.
126 /// If None is returned, the DropArena will be used.
127 fn arena<'a>(arena: &'a Arena<'tcx>) -> Option<&'a TypedArena<Self>>;
130 unsafe impl<'tcx, T> ArenaField<'tcx> for T {
132 default fn arena<'a>(_: &'a Arena<'tcx>) -> Option<&'a TypedArena<Self>> {
137 impl<'tcx> Arena<'tcx> {
139 pub fn alloc<T: ArenaAllocatable>(&self, value: T) -> &mut T {
140 if !mem::needs_drop::<T>() {
141 return self.dropless.alloc(value);
143 match <T as ArenaField<'tcx>>::arena(self) {
144 Some(arena) => arena.alloc(value),
145 None => unsafe { self.drop.alloc(value) },
150 pub fn alloc_slice<T: Copy>(&self, value: &[T]) -> &mut [T] {
151 if value.len() == 0 {
154 self.dropless.alloc_slice(value)
157 pub fn alloc_from_iter<
159 I: IntoIterator<Item = T>
164 if !mem::needs_drop::<T>() {
165 return self.dropless.alloc_from_iter(iter);
167 match <T as ArenaField<'tcx>>::arena(self) {
168 Some(arena) => arena.alloc_from_iter(iter),
169 None => unsafe { self.drop.alloc_from_iter(iter) },
174 /// Calls the destructor for an object when dropped.
176 drop_fn: unsafe fn(*mut u8),
180 unsafe fn drop_for_type<T>(to_drop: *mut u8) {
181 std::ptr::drop_in_place(to_drop as *mut T)
184 impl Drop for DropType {
187 (self.drop_fn)(self.obj)
192 /// An arena which can be used to allocate any type.
193 /// Allocating in this arena is unsafe since the type system
194 /// doesn't know which types it contains. In order to
195 /// allocate safely, you must store a PhantomData<T>
196 /// alongside this arena for each type T you allocate.
199 /// A list of destructors to run when the arena drops.
200 /// Ordered so `destructors` gets dropped before the arena
201 /// since its destructor can reference memory in the arena.
202 destructors: RefCell<Vec<DropType>>,
203 arena: DroplessArena,
208 unsafe fn alloc<T>(&self, object: T) -> &mut T {
209 let mem = self.arena.alloc_raw(
212 ) as *mut _ as *mut T;
213 // Write into uninitialized memory.
214 ptr::write(mem, object);
215 let result = &mut *mem;
216 // Record the destructor after doing the allocation as that may panic
217 // and would cause `object`'s destuctor to run twice if it was recorded before
218 self.destructors.borrow_mut().push(DropType {
219 drop_fn: drop_for_type::<T>,
220 obj: result as *mut T as *mut u8,
226 unsafe fn alloc_from_iter<T, I: IntoIterator<Item = T>>(&self, iter: I) -> &mut [T] {
227 let mut vec: SmallVec<[_; 8]> = iter.into_iter().collect();
233 let start_ptr = self.arena.alloc_raw(
234 len.checked_mul(mem::size_of::<T>()).unwrap(),
236 ) as *mut _ as *mut T;
238 let mut destructors = self.destructors.borrow_mut();
239 // Reserve space for the destructors so we can't panic while adding them
240 destructors.reserve(len);
242 // Move the content to the arena by copying it and then forgetting
243 // the content of the SmallVec
244 vec.as_ptr().copy_to_nonoverlapping(start_ptr, len);
245 mem::forget(vec.drain());
247 // Record the destructors after doing the allocation as that may panic
248 // and would cause `object`'s destuctor to run twice if it was recorded before
250 destructors.push(DropType {
251 drop_fn: drop_for_type::<T>,
252 obj: start_ptr.offset(i as isize) as *mut u8,
256 slice::from_raw_parts_mut(start_ptr, len)