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hcx.rs
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hcx.rs
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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use hir;
use hir::def_id::{DefId, DefIndex};
use hir::map::DefPathHash;
use hir::map::definitions::Definitions;
use ich::{self, CachingCodemapView, Fingerprint};
use middle::cstore::CrateStore;
use ty::{TyCtxt, fast_reject};
use session::Session;
use std::cmp::Ord;
use std::hash as std_hash;
use std::cell::RefCell;
use std::collections::HashMap;
use syntax::ast;
use syntax::codemap::CodeMap;
use syntax::ext::hygiene::SyntaxContext;
use syntax::symbol::Symbol;
use syntax_pos::{Span, DUMMY_SP};
use syntax_pos::hygiene;
use rustc_data_structures::stable_hasher::{HashStable, StableHashingContextProvider,
StableHasher, StableHasherResult,
ToStableHashKey};
use rustc_data_structures::accumulate_vec::AccumulateVec;
use rustc_data_structures::fx::{FxHashSet, FxHashMap};
thread_local!(static IGNORED_ATTR_NAMES: RefCell<FxHashSet<Symbol>> =
RefCell::new(FxHashSet()));
/// This is the context state available during incr. comp. hashing. It contains
/// enough information to transform DefIds and HirIds into stable DefPaths (i.e.
/// a reference to the TyCtxt) and it holds a few caches for speeding up various
/// things (e.g. each DefId/DefPath is only hashed once).
#[derive(Clone)]
pub struct StableHashingContext<'gcx> {
sess: &'gcx Session,
definitions: &'gcx Definitions,
cstore: &'gcx CrateStore,
body_resolver: BodyResolver<'gcx>,
hash_spans: bool,
hash_bodies: bool,
node_id_hashing_mode: NodeIdHashingMode,
// Very often, we are hashing something that does not need the
// CachingCodemapView, so we initialize it lazily.
raw_codemap: &'gcx CodeMap,
caching_codemap: Option<CachingCodemapView<'gcx>>,
}
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum NodeIdHashingMode {
Ignore,
HashDefPath,
}
/// The BodyResolver allows to map a BodyId to the corresponding hir::Body.
/// We could also just store a plain reference to the hir::Crate but we want
/// to avoid that the crate is used to get untracked access to all of the HIR.
#[derive(Clone, Copy)]
struct BodyResolver<'gcx>(&'gcx hir::Crate);
impl<'gcx> BodyResolver<'gcx> {
// Return a reference to the hir::Body with the given BodyId.
// DOES NOT DO ANY TRACKING, use carefully.
fn body(self, id: hir::BodyId) -> &'gcx hir::Body {
self.0.body(id)
}
}
impl<'gcx> StableHashingContext<'gcx> {
// The `krate` here is only used for mapping BodyIds to Bodies.
// Don't use it for anything else or you'll run the risk of
// leaking data out of the tracking system.
pub fn new(sess: &'gcx Session,
krate: &'gcx hir::Crate,
definitions: &'gcx Definitions,
cstore: &'gcx CrateStore)
-> Self {
let hash_spans_initial = !sess.opts.debugging_opts.incremental_ignore_spans;
debug_assert!(ich::IGNORED_ATTRIBUTES.len() > 0);
IGNORED_ATTR_NAMES.with(|names| {
let mut names = names.borrow_mut();
if names.is_empty() {
names.extend(ich::IGNORED_ATTRIBUTES.iter()
.map(|&s| Symbol::intern(s)));
}
});
StableHashingContext {
sess,
body_resolver: BodyResolver(krate),
definitions,
cstore,
caching_codemap: None,
raw_codemap: sess.codemap(),
hash_spans: hash_spans_initial,
hash_bodies: true,
node_id_hashing_mode: NodeIdHashingMode::HashDefPath,
}
}
#[inline]
pub fn sess(&self) -> &'gcx Session {
self.sess
}
#[inline]
pub fn while_hashing_hir_bodies<F: FnOnce(&mut Self)>(&mut self,
hash_bodies: bool,
f: F) {
let prev_hash_bodies = self.hash_bodies;
self.hash_bodies = hash_bodies;
f(self);
self.hash_bodies = prev_hash_bodies;
}
#[inline]
pub fn while_hashing_spans<F: FnOnce(&mut Self)>(&mut self,
hash_spans: bool,
f: F) {
let prev_hash_spans = self.hash_spans;
self.hash_spans = hash_spans;
f(self);
self.hash_spans = prev_hash_spans;
}
#[inline]
pub fn with_node_id_hashing_mode<F: FnOnce(&mut Self)>(&mut self,
mode: NodeIdHashingMode,
f: F) {
let prev = self.node_id_hashing_mode;
self.node_id_hashing_mode = mode;
f(self);
self.node_id_hashing_mode = prev;
}
#[inline]
pub fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
if def_id.is_local() {
self.definitions.def_path_hash(def_id.index)
} else {
self.cstore.def_path_hash(def_id)
}
}
#[inline]
pub fn local_def_path_hash(&self, def_index: DefIndex) -> DefPathHash {
self.definitions.def_path_hash(def_index)
}
#[inline]
pub fn node_to_hir_id(&self, node_id: ast::NodeId) -> hir::HirId {
self.definitions.node_to_hir_id(node_id)
}
#[inline]
pub fn hash_bodies(&self) -> bool {
self.hash_bodies
}
#[inline]
pub fn codemap(&mut self) -> &mut CachingCodemapView<'gcx> {
match self.caching_codemap {
Some(ref mut cm) => {
cm
}
ref mut none => {
*none = Some(CachingCodemapView::new(self.raw_codemap));
none.as_mut().unwrap()
}
}
}
#[inline]
pub fn is_ignored_attr(&self, name: Symbol) -> bool {
IGNORED_ATTR_NAMES.with(|names| {
names.borrow().contains(&name)
})
}
pub fn hash_hir_item_like<F: FnOnce(&mut Self)>(&mut self, f: F) {
let prev_hash_node_ids = self.node_id_hashing_mode;
self.node_id_hashing_mode = NodeIdHashingMode::Ignore;
f(self);
self.node_id_hashing_mode = prev_hash_node_ids;
}
}
impl<'a, 'gcx, 'lcx> StableHashingContextProvider for TyCtxt<'a, 'gcx, 'lcx> {
type ContextType = StableHashingContext<'gcx>;
fn create_stable_hashing_context(&self) -> Self::ContextType {
(*self).create_stable_hashing_context()
}
}
impl<'gcx> StableHashingContextProvider for StableHashingContext<'gcx> {
type ContextType = StableHashingContext<'gcx>;
fn create_stable_hashing_context(&self) -> Self::ContextType {
self.clone()
}
}
impl<'gcx> ::dep_graph::DepGraphSafe for StableHashingContext<'gcx> {
}
impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::BodyId {
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>) {
if hcx.hash_bodies() {
hcx.body_resolver.body(*self).hash_stable(hcx, hasher);
}
}
}
impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::HirId {
#[inline]
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>) {
match hcx.node_id_hashing_mode {
NodeIdHashingMode::Ignore => {
// Don't do anything.
}
NodeIdHashingMode::HashDefPath => {
let hir::HirId {
owner,
local_id,
} = *self;
hcx.local_def_path_hash(owner).hash_stable(hcx, hasher);
local_id.hash_stable(hcx, hasher);
}
}
}
}
impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for hir::HirId {
type KeyType = (DefPathHash, hir::ItemLocalId);
#[inline]
fn to_stable_hash_key(&self,
hcx: &StableHashingContext<'gcx>)
-> (DefPathHash, hir::ItemLocalId) {
let def_path_hash = hcx.local_def_path_hash(self.owner);
(def_path_hash, self.local_id)
}
}
impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::NodeId {
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>) {
match hcx.node_id_hashing_mode {
NodeIdHashingMode::Ignore => {
// Don't do anything.
}
NodeIdHashingMode::HashDefPath => {
hcx.definitions.node_to_hir_id(*self).hash_stable(hcx, hasher);
}
}
}
}
impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for ast::NodeId {
type KeyType = (DefPathHash, hir::ItemLocalId);
#[inline]
fn to_stable_hash_key(&self,
hcx: &StableHashingContext<'gcx>)
-> (DefPathHash, hir::ItemLocalId) {
hcx.definitions.node_to_hir_id(*self).to_stable_hash_key(hcx)
}
}
impl<'gcx> HashStable<StableHashingContext<'gcx>> for Span {
// Hash a span in a stable way. We can't directly hash the span's BytePos
// fields (that would be similar to hashing pointers, since those are just
// offsets into the CodeMap). Instead, we hash the (file name, line, column)
// triple, which stays the same even if the containing FileMap has moved
// within the CodeMap.
// Also note that we are hashing byte offsets for the column, not unicode
// codepoint offsets. For the purpose of the hash that's sufficient.
// Also, hashing filenames is expensive so we avoid doing it twice when the
// span starts and ends in the same file, which is almost always the case.
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>) {
const TAG_VALID_SPAN: u8 = 0;
const TAG_INVALID_SPAN: u8 = 1;
const TAG_EXPANSION: u8 = 0;
const TAG_NO_EXPANSION: u8 = 1;
if !hcx.hash_spans {
return
}
if *self == DUMMY_SP {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}
// If this is not an empty or invalid span, we want to hash the last
// position that belongs to it, as opposed to hashing the first
// position past it.
let span = self.data();
if span.hi < span.lo {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}
let (file_lo, line_lo, col_lo) = match hcx.codemap()
.byte_pos_to_line_and_col(span.lo) {
Some(pos) => pos,
None => {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}
};
if !file_lo.contains(span.hi) {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}
std_hash::Hash::hash(&TAG_VALID_SPAN, hasher);
// We truncate the stable_id hash and line and col numbers. The chances
// of causing a collision this way should be minimal.
std_hash::Hash::hash(&(file_lo.name_hash as u64), hasher);
let col = (col_lo.0 as u64) & 0xFF;
let line = ((line_lo as u64) & 0xFF_FF_FF) << 8;
let len = ((span.hi - span.lo).0 as u64) << 32;
let line_col_len = col | line | len;
std_hash::Hash::hash(&line_col_len, hasher);
if span.ctxt == SyntaxContext::empty() {
TAG_NO_EXPANSION.hash_stable(hcx, hasher);
} else {
TAG_EXPANSION.hash_stable(hcx, hasher);
// Since the same expansion context is usually referenced many
// times, we cache a stable hash of it and hash that instead of
// recursing every time.
thread_local! {
static CACHE: RefCell<FxHashMap<hygiene::Mark, u64>> =
RefCell::new(FxHashMap());
}
let sub_hash: u64 = CACHE.with(|cache| {
let mark = span.ctxt.outer();
if let Some(&sub_hash) = cache.borrow().get(&mark) {
return sub_hash;
}
let mut hasher = StableHasher::new();
mark.expn_info().hash_stable(hcx, &mut hasher);
let sub_hash: Fingerprint = hasher.finish();
let sub_hash = sub_hash.to_smaller_hash();
cache.borrow_mut().insert(mark, sub_hash);
sub_hash
});
sub_hash.hash_stable(hcx, hasher);
}
}
}
pub fn hash_stable_trait_impls<'gcx, W, R>(
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>,
blanket_impls: &Vec<DefId>,
non_blanket_impls: &HashMap<fast_reject::SimplifiedType, Vec<DefId>, R>)
where W: StableHasherResult,
R: std_hash::BuildHasher,
{
{
let mut blanket_impls: AccumulateVec<[_; 8]> = blanket_impls
.iter()
.map(|&def_id| hcx.def_path_hash(def_id))
.collect();
if blanket_impls.len() > 1 {
blanket_impls.sort_unstable();
}
blanket_impls.hash_stable(hcx, hasher);
}
{
let mut keys: AccumulateVec<[_; 8]> =
non_blanket_impls.keys()
.map(|k| (k, k.map_def(|d| hcx.def_path_hash(d))))
.collect();
keys.sort_unstable_by(|&(_, ref k1), &(_, ref k2)| k1.cmp(k2));
keys.len().hash_stable(hcx, hasher);
for (key, ref stable_key) in keys {
stable_key.hash_stable(hcx, hasher);
let mut impls : AccumulateVec<[_; 8]> = non_blanket_impls[key]
.iter()
.map(|&impl_id| hcx.def_path_hash(impl_id))
.collect();
if impls.len() > 1 {
impls.sort_unstable();
}
impls.hash_stable(hcx, hasher);
}
}
}