Utilize new in_arena method instead of hashing for Lifting interned items

Author: Mark-Simulacrum

src/libarena/lib.rs

@@ -301,6 +301,17 @@ impl DroplessArena {
  }
  }
 
+ pub fn in_arena<T: ?Sized>(&self, ptr: *const T) -> bool {
+ let ptr = ptr as *const u8 as *mut u8;
+ for chunk in &*self.chunks.borrow() {
+ if chunk.start() <= ptr && ptr < chunk.end() {
+ return true;
+ }
+ }
+
+ false
+ }
+
  fn align_for<T>(&self) {
  let align = mem::align_of::<T>();
  let final_address = ((self.ptr.get() as usize) + align - 1) & !(align - 1);
@@ -330,12 +341,11 @@ impl DroplessArena {
  }
  }
  } else {
- new_capacity = needed_bytes;
+ new_capacity = cmp::max(needed_bytes, PAGE);
  }
  chunk = TypedArenaChunk::<u8>::new(new_capacity);
  self.ptr.set(chunk.start());
  self.end.set(chunk.end());
- self.align_for::<T>();
  chunks.push(chunk);
  }
  }

src/librustc/ty/context.rs

@@ -817,10 +817,8 @@ pub trait Lift<'tcx> {
 impl<'a, 'tcx> Lift<'tcx> for Ty<'a> {
  type Lifted = Ty<'tcx>;
  fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Ty<'tcx>> {
- if let Some(&Interned(ty)) = tcx.interners.type_.borrow().get(&self.sty) {
- if *self as *const _ == ty as *const _ {
- return Some(ty);
- }
+ if tcx.interners.arena.in_arena(*self as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -837,10 +835,8 @@ impl<'a, 'tcx> Lift<'tcx> for &'a Substs<'a> {
  if self.len() == 0 {
  return Some(Slice::empty());
  }
- if let Some(&Interned(substs)) = tcx.interners.substs.borrow().get(&self[..]) {
- if *self as *const _ == substs as *const _ {
- return Some(substs);
- }
+ if tcx.interners.arena.in_arena(&self[..] as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -854,10 +850,8 @@ impl<'a, 'tcx> Lift<'tcx> for &'a Substs<'a> {
 impl<'a, 'tcx> Lift<'tcx> for &'a Region {
  type Lifted = &'tcx Region;
  fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<&'tcx Region> {
- if let Some(&Interned(region)) = tcx.interners.region.borrow().get(*self) {
- if *self as *const _ == region as *const _ {
- return Some(region);
- }
+ if tcx.interners.arena.in_arena(*self as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -875,10 +869,8 @@ impl<'a, 'tcx> Lift<'tcx> for &'a Slice<Ty<'a>> {
  if self.len() == 0 {
  return Some(Slice::empty());
  }
- if let Some(&Interned(list)) = tcx.interners.type_list.borrow().get(&self[..]) {
- if *self as *const _ == list as *const _ {
- return Some(list);
- }
+ if tcx.interners.arena.in_arena(*self as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -896,10 +888,8 @@ impl<'a, 'tcx> Lift<'tcx> for &'a Slice<ExistentialPredicate<'a>> {
  if self.is_empty() {
  return Some(Slice::empty());
  }
- if let Some(&Interned(eps)) = tcx.interners.existential_predicates.borrow().get(&self[..]) {
- if *self as *const _ == eps as *const _ {
- return Some(eps);
- }
+ if tcx.interners.arena.in_arena(*self as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -914,10 +904,8 @@ impl<'a, 'tcx> Lift<'tcx> for &'a BareFnTy<'a> {
  type Lifted = &'tcx BareFnTy<'tcx>;
  fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
  -> Option<&'tcx BareFnTy<'tcx>> {
- if let Some(&Interned(fty)) = tcx.interners.bare_fn.borrow().get(*self) {
- if *self as *const _ == fty as *const _ {
- return Some(fty);
- }
+ if tcx.interners.arena.in_arena(*self as *const _) {
+ return Some(unsafe { mem::transmute(*self) });
  }
  // Also try in the global tcx if we're not that.
  if !tcx.is_global() {
@@ -1201,7 +1189,7 @@ macro_rules! intern_method {
  }
  }
 
- let i = ($alloc_to_ret)(self.global_interners.arena.$alloc_method(v));
+ let i = ($alloc_to_ret)(self.interners.arena.$alloc_method(v));
  self.interners.$name.borrow_mut().insert(Interned(i));
  i
  }