compiler/rustc_middle/src/ty/impls_ty.rs

   1 //! This module contains `HashStable` implementations for various data types
   2 //! from `rustc_middle::ty` in no particular order.
   3
   4 use crate::middle::region;
   5 use crate::mir;
   6 use crate::ty;
   7 use crate::ty::fast_reject::SimplifiedType;
   8 use rustc_data_structures::fingerprint::Fingerprint;
   9 use rustc_data_structures::fx::FxHashMap;
  10 use rustc_data_structures::stable_hasher::HashingControls;
  11 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
  12 use rustc_query_system::ich::StableHashingContext;
  13 use std::cell::RefCell;
  14
  15 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for &'tcx ty::List<T>
  16 where
  17     T: HashStable<StableHashingContext<'a>>,
  18 {
  19     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
  20         thread_local! {
  21             static CACHE: RefCell<FxHashMap<(usize, usize, HashingControls), Fingerprint>> =
  22                 RefCell::new(Default::default());
  23         }
  24
  25         let hash = CACHE.with(|cache| {
  26             let key = (self.as_ptr() as usize, self.len(), hcx.hashing_controls());
  27             if let Some(&hash) = cache.borrow().get(&key) {
  28                 return hash;
  29             }
  30
  31             let mut hasher = StableHasher::new();
  32             (&self[..]).hash_stable(hcx, &mut hasher);
  33
  34             let hash: Fingerprint = hasher.finish();
  35             cache.borrow_mut().insert(key, hash);
  36             hash
  37         });
  38
  39         hash.hash_stable(hcx, hasher);
  40     }
  41 }
  42
  43 impl<'a, 'tcx, T> ToStableHashKey<StableHashingContext<'a>> for &'tcx ty::List<T>
  44 where
  45     T: HashStable<StableHashingContext<'a>>,
  46 {
  47     type KeyType = Fingerprint;
  48
  49     #[inline]
  50     fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> Fingerprint {
  51         let mut hasher = StableHasher::new();
  52         let mut hcx: StableHashingContext<'a> = hcx.clone();
  53         self.hash_stable(&mut hcx, &mut hasher);
  54         hasher.finish()
  55     }
  56 }
  57
  58 impl<'a> ToStableHashKey<StableHashingContext<'a>> for SimplifiedType {
  59     type KeyType = Fingerprint;
  60
  61     #[inline]
  62     fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> Fingerprint {
  63         let mut hasher = StableHasher::new();
  64         let mut hcx: StableHashingContext<'a> = hcx.clone();
  65         self.hash_stable(&mut hcx, &mut hasher);
  66         hasher.finish()
  67     }
  68 }
  69
  70 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ty::subst::GenericArg<'tcx> {
  71     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
  72         self.unpack().hash_stable(hcx, hasher);
  73     }
  74 }
  75
  76 // AllocIds get resolved to whatever they point to (to be stable)
  77 impl<'a> HashStable<StableHashingContext<'a>> for mir::interpret::AllocId {
  78     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
  79         ty::tls::with_opt(|tcx| {
  80             trace!("hashing {:?}", *self);
  81             let tcx = tcx.expect("can't hash AllocIds during hir lowering");
  82             tcx.try_get_global_alloc(*self).hash_stable(hcx, hasher);
  83         });
  84     }
  85 }
  86
  87 impl<'a> ToStableHashKey<StableHashingContext<'a>> for region::Scope {
  88     type KeyType = region::Scope;
  89
  90     #[inline]
  91     fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> region::Scope {
  92         *self
  93     }
  94 }