Introduce HashStable trait and base ICH implementations on it.

This initial commit provides implementations for HIR, MIR, and
everything that also needs to be supported for those two.

src/librustc/hir/map/definitions.rs

@@ -394,6 +394,10 @@ pub fn as_local_node_id(&self, def_id: DefId) -> Option<ast::NodeId> {
         }
     }
 
+    pub fn node_to_hir_id(&self, node_id: ast::NodeId) -> hir::HirId {
+        self.node_to_hir_id[node_id]
+    }
+
     /// Add a definition with a parent definition.
     pub fn create_def_with_parent(&mut self,
                                   parent: Option<DefIndex>,

src/librustc/ich/hcx.rs

+// 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;
+use ich::{self, CachingCodemapView, DefPathHashes};
+use session::config::DebugInfoLevel::NoDebugInfo;
+use ty;
+
+use std::hash as std_hash;
+
+use syntax::ast;
+use syntax::attr;
+use syntax::ext::hygiene::SyntaxContext;
+use syntax::symbol::Symbol;
+use syntax_pos::Span;
+
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHasherResult};
+use rustc_data_structures::accumulate_vec::AccumulateVec;
+
+/// 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).
+pub struct StableHashingContext<'a, 'tcx: 'a> {
+    tcx: ty::TyCtxt<'a, 'tcx, 'tcx>,
+    def_path_hashes: DefPathHashes<'a, 'tcx>,
+    codemap: CachingCodemapView<'tcx>,
+    hash_spans: bool,
+    hash_bodies: bool,
+    overflow_checks_enabled: bool,
+    node_id_hashing_mode: NodeIdHashingMode,
+    // A sorted array of symbol keys for fast lookup.
+    ignored_attr_names: Vec<Symbol>,
+}
+
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub enum NodeIdHashingMode {
+    Ignore,
+    HashDefPath,
+    HashTraitsInScope,
+}
+
+impl<'a, 'tcx: 'a> StableHashingContext<'a, 'tcx> {
+
+    pub fn new(tcx: ty::TyCtxt<'a, 'tcx, 'tcx>) -> Self {
+        let hash_spans_initial = tcx.sess.opts.debuginfo != NoDebugInfo;
+        let check_overflow_initial = tcx.sess.overflow_checks();
+
+        let mut ignored_attr_names: Vec<_> = ich::IGNORED_ATTRIBUTES
+            .iter()
+            .map(|&s| Symbol::intern(s))
+            .collect();
+
+        ignored_attr_names.sort();
+
+        StableHashingContext {
+            tcx: tcx,
+            def_path_hashes: DefPathHashes::new(tcx),
+            codemap: CachingCodemapView::new(tcx),
+            hash_spans: hash_spans_initial,
+            hash_bodies: true,
+            overflow_checks_enabled: check_overflow_initial,
+            node_id_hashing_mode: NodeIdHashingMode::HashDefPath,
+            ignored_attr_names: ignored_attr_names,
+        }
+    }
+
+    #[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 tcx(&self) -> ty::TyCtxt<'a, 'tcx, 'tcx> {
+        self.tcx
+    }
+
+    #[inline]
+    pub fn def_path_hash(&mut self, def_id: DefId) -> u64 {
+        self.def_path_hashes.hash(def_id)
+    }
+
+    #[inline]
+    pub fn hash_spans(&self) -> bool {
+        self.hash_spans
+    }
+
+    #[inline]
+    pub fn hash_bodies(&self) -> bool {
+        self.hash_bodies
+    }
+
+    #[inline]
+    pub fn codemap(&mut self) -> &mut CachingCodemapView<'tcx> {
+        &mut self.codemap
+    }
+
+    #[inline]
+    pub fn is_ignored_attr(&self, name: Symbol) -> bool {
+        self.ignored_attr_names.binary_search(&name).is_ok()
+    }
+
+    pub fn hash_hir_item_like<F: FnOnce(&mut Self)>(&mut self,
+                                                    item_attrs: &[ast::Attribute],
+                                                    f: F) {
+        let prev_overflow_checks = self.overflow_checks_enabled;
+        if attr::contains_name(item_attrs, "rustc_inherit_overflow_checks") {
+            self.overflow_checks_enabled = true;
+        }
+        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;
+        self.overflow_checks_enabled = prev_overflow_checks;
+    }
+
+    #[inline]
+    pub fn binop_can_panic_at_runtime(&self, binop: hir::BinOp_) -> bool
+    {
+        match binop {
+            hir::BiAdd |
+            hir::BiSub |
+            hir::BiMul => self.overflow_checks_enabled,
+
+            hir::BiDiv |
+            hir::BiRem => true,
+
+            hir::BiAnd |
+            hir::BiOr |
+            hir::BiBitXor |
+            hir::BiBitAnd |
+            hir::BiBitOr |
+            hir::BiShl |
+            hir::BiShr |
+            hir::BiEq |
+            hir::BiLt |
+            hir::BiLe |
+            hir::BiNe |
+            hir::BiGe |
+            hir::BiGt => false
+        }
+    }
+
+    #[inline]
+    pub fn unop_can_panic_at_runtime(&self, unop: hir::UnOp) -> bool
+    {
+        match unop {
+            hir::UnDeref |
+            hir::UnNot => false,
+            hir::UnNeg => self.overflow_checks_enabled,
+        }
+    }
+}
+
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ast::NodeId {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        match hcx.node_id_hashing_mode {
+            NodeIdHashingMode::Ignore => {
+                // Most NodeIds in the HIR can be ignored, but if there is a
+                // corresponding entry in the `trait_map` we need to hash that.
+                // Make sure we don't ignore too much by checking that there is
+                // no entry in a debug_assert!().
+                debug_assert!(hcx.tcx.trait_map.get(self).is_none());
+            }
+            NodeIdHashingMode::HashDefPath => {
+                hcx.tcx.hir.definitions().node_to_hir_id(*self).hash_stable(hcx, hasher);
+            }
+            NodeIdHashingMode::HashTraitsInScope => {
+                if let Some(traits) = hcx.tcx.trait_map.get(self) {
+                    // The ordering of the candidates is not fixed. So we hash
+                    // the def-ids and then sort them and hash the collection.
+                    let mut candidates: AccumulateVec<[_; 8]> =
+                        traits.iter()
+                              .map(|&hir::TraitCandidate { def_id, import_id: _ }| {
+                                  hcx.def_path_hash(def_id)
+                              })
+                              .collect();
+                    if traits.len() > 1 {
+                        candidates.sort();
+                    }
+                    candidates.hash_stable(hcx, hasher);
+                }
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> 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<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use syntax_pos::Pos;
+
+        if !hcx.hash_spans {
+            return
+        }
+
+        // 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_hi = if self.hi > self.lo {
+            // We might end up in the middle of a multibyte character here,
+            // but that's OK, since we are not trying to decode anything at
+            // this position.
+            self.hi - ::syntax_pos::BytePos(1)
+        } else {
+            self.hi
+        };
+
+        {
+            let loc1 = hcx.codemap().byte_pos_to_line_and_col(self.lo);
+            let loc1 = loc1.as_ref()
+                           .map(|&(ref fm, line, col)| (&fm.name[..], line, col.to_usize()))
+                           .unwrap_or(("???", 0, 0));
+
+            let loc2 = hcx.codemap().byte_pos_to_line_and_col(span_hi);
+            let loc2 = loc2.as_ref()
+                           .map(|&(ref fm, line, col)| (&fm.name[..], line, col.to_usize()))
+                           .unwrap_or(("???", 0, 0));
+
+            if loc1.0 == loc2.0 {
+                std_hash::Hash::hash(&0u8, hasher);
+
+                std_hash::Hash::hash(loc1.0, hasher);
+                std_hash::Hash::hash(&loc1.1, hasher);
+                std_hash::Hash::hash(&loc1.2, hasher);
+
+                // Do not hash the file name twice
+                std_hash::Hash::hash(&loc2.1, hasher);
+                std_hash::Hash::hash(&loc2.2, hasher);
+            } else {
+                std_hash::Hash::hash(&1u8, hasher);
+
+                std_hash::Hash::hash(loc1.0, hasher);
+                std_hash::Hash::hash(&loc1.1, hasher);
+                std_hash::Hash::hash(&loc1.2, hasher);
+
+                std_hash::Hash::hash(loc2.0, hasher);
+                std_hash::Hash::hash(&loc2.1, hasher);
+                std_hash::Hash::hash(&loc2.2, hasher);
+            }
+        }
+
+        if self.ctxt == SyntaxContext::empty() {
+            0u8.hash_stable(hcx, hasher);
+        } else {
+            1u8.hash_stable(hcx, hasher);
+            self.source_callsite().hash_stable(hcx, hasher);
+        }
+    }
+}

src/librustc/ich/impls_const_math.rs

+// 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.
+
+//! This module contains `HashStable` implementations for various data types
+//! from `rustc_const_math` in no particular order.
+
+impl_stable_hash_for!(enum ::rustc_const_math::ConstFloat {
+    F32(val),
+    F64(val)
+});
+
+impl_stable_hash_for!(enum ::rustc_const_math::ConstInt {
+    I8(val),
+    I16(val),
+    I32(val),
+    I64(val),
+    I128(val),
+    Isize(val),
+    U8(val),
+    U16(val),
+    U32(val),
+    U64(val),
+    U128(val),
+    Usize(val)
+});
+
+impl_stable_hash_for!(enum ::rustc_const_math::ConstIsize {
+    Is16(i16),
+    Is32(i32),
+    Is64(i64)
+});
+
+impl_stable_hash_for!(enum ::rustc_const_math::ConstUsize {
+    Us16(i16),
+    Us32(i32),
+    Us64(i64)
+});
+
+impl_stable_hash_for!(enum ::rustc_const_math::ConstMathErr {
+    NotInRange,
+    CmpBetweenUnequalTypes,
+    UnequalTypes(op),
+    Overflow(op),
+    ShiftNegative,
+    DivisionByZero,
+    RemainderByZero,
+    UnsignedNegation,
+    ULitOutOfRange(int_ty),
+    LitOutOfRange(int_ty)
+});
+
+impl_stable_hash_for!(enum ::rustc_const_math::Op {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Rem,
+    Shr,
+    Shl,
+    Neg,
+    BitAnd,
+    BitOr,
+    BitXor
+});

src/librustc/ich/impls_mir.rs

+// 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.
+
+//! This module contains `HashStable` implementations for various MIR data
+//! types in no particular order.
+
+use ich::StableHashingContext;
+use mir;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHasherResult};
+use std::mem;
+
+
+impl_stable_hash_for!(struct mir::SourceInfo { span, scope });
+impl_stable_hash_for!(enum mir::Mutability { Mut, Not });
+impl_stable_hash_for!(enum mir::BorrowKind { Shared, Unique, Mut });
+impl_stable_hash_for!(enum mir::LocalKind { Var, Temp, Arg, ReturnPointer });
+impl_stable_hash_for!(struct mir::LocalDecl<'tcx> { mutability, ty, name, source_info });
+impl_stable_hash_for!(struct mir::UpvarDecl { debug_name, by_ref });
+impl_stable_hash_for!(struct mir::BasicBlockData<'tcx> { statements, terminator, is_cleanup });
+impl_stable_hash_for!(struct mir::Terminator<'tcx> { source_info, kind });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Local {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use rustc_data_structures::indexed_vec::Idx;
+        self.index().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::BasicBlock {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use rustc_data_structures::indexed_vec::Idx;
+        self.index().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Field {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use rustc_data_structures::indexed_vec::Idx;
+        self.index().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::VisibilityScope {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use rustc_data_structures::indexed_vec::Idx;
+        self.index().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Promoted {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use rustc_data_structures::indexed_vec::Idx;
+        self.index().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::TerminatorKind<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            mir::TerminatorKind::Goto { ref target } => {
+                target.hash_stable(hcx, hasher);
+            }
+            mir::TerminatorKind::SwitchInt { ref discr,
+                                             switch_ty,
+                                             ref values,
+                                             ref targets } => {
+                discr.hash_stable(hcx, hasher);
+                switch_ty.hash_stable(hcx, hasher);
+                values.hash_stable(hcx, hasher);
+                targets.hash_stable(hcx, hasher);
+            }
+            mir::TerminatorKind::Resume |
+            mir::TerminatorKind::Return |
+            mir::TerminatorKind::Unreachable => {}
+            mir::TerminatorKind::Drop { ref location, target, unwind } => {
+                location.hash_stable(hcx, hasher);
+                target.hash_stable(hcx, hasher);
+                unwind.hash_stable(hcx, hasher);
+            }
+            mir::TerminatorKind::DropAndReplace { ref location,
+                                                  ref value,
+                                                  target,
+                                                  unwind, } => {
+                location.hash_stable(hcx, hasher);
+                value.hash_stable(hcx, hasher);
+                target.hash_stable(hcx, hasher);
+                unwind.hash_stable(hcx, hasher);
+            }
+            mir::TerminatorKind::Call { ref func,
+                                        ref args,
+                                        ref destination,
+                                        cleanup } => {
+                func.hash_stable(hcx, hasher);
+                args.hash_stable(hcx, hasher);
+                destination.hash_stable(hcx, hasher);
+                cleanup.hash_stable(hcx, hasher);
+            }
+            mir::TerminatorKind::Assert { ref cond,
+                                          expected,
+                                          ref msg,
+                                          target,
+                                          cleanup } => {
+                cond.hash_stable(hcx, hasher);
+                expected.hash_stable(hcx, hasher);
+                msg.hash_stable(hcx, hasher);
+                target.hash_stable(hcx, hasher);
+                cleanup.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::AssertMessage<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            mir::AssertMessage::BoundsCheck { ref len, ref index } => {
+                len.hash_stable(hcx, hasher);
+                index.hash_stable(hcx, hasher);
+            }
+            mir::AssertMessage::Math(ref const_math_err) => {
+                const_math_err.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct mir::Statement<'tcx> { source_info, kind });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::StatementKind<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            mir::StatementKind::Assign(ref lvalue, ref rvalue) => {
+                lvalue.hash_stable(hcx, hasher);
+                rvalue.hash_stable(hcx, hasher);
+            }
+            mir::StatementKind::SetDiscriminant { ref lvalue, variant_index } => {
+                lvalue.hash_stable(hcx, hasher);
+                variant_index.hash_stable(hcx, hasher);
+            }
+            mir::StatementKind::StorageLive(ref lvalue) |
+            mir::StatementKind::StorageDead(ref lvalue) => {
+                lvalue.hash_stable(hcx, hasher);
+            }
+            mir::StatementKind::Nop => {}
+            mir::StatementKind::InlineAsm { ref asm, ref outputs, ref inputs } => {
+                asm.hash_stable(hcx, hasher);
+                outputs.hash_stable(hcx, hasher);
+                inputs.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Lvalue<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            mir::Lvalue::Local(ref local) => {
+                local.hash_stable(hcx, hasher);
+            }
+            mir::Lvalue::Static(ref statik) => {
+                statik.hash_stable(hcx, hasher);
+            }
+            mir::Lvalue::Projection(ref lvalue_projection) => {
+                lvalue_projection.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx, B, V> HashStable<StableHashingContext<'a, 'tcx>> for mir::Projection<'tcx, B, V>
+    where B: HashStable<StableHashingContext<'a, 'tcx>>,
+          V: HashStable<StableHashingContext<'a, 'tcx>>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let mir::Projection {
+            ref base,
+            ref elem,
+        } = *self;
+
+        base.hash_stable(hcx, hasher);
+        elem.hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx, V> HashStable<StableHashingContext<'a, 'tcx>> for mir::ProjectionElem<'tcx, V>
+    where V: HashStable<StableHashingContext<'a, 'tcx>>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            mir::ProjectionElem::Deref => {}
+            mir::ProjectionElem::Field(field, ty) => {
+                field.hash_stable(hcx, hasher);
+                ty.hash_stable(hcx, hasher);
+            }
+            mir::ProjectionElem::Index(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            mir::ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
+                offset.hash_stable(hcx, hasher);
+                min_length.hash_stable(hcx, hasher);
+                from_end.hash_stable(hcx, hasher);
+            }
+            mir::ProjectionElem::Subslice { from, to } => {
+                from.hash_stable(hcx, hasher);
+                to.hash_stable(hcx, hasher);
+            }
+            mir::ProjectionElem::Downcast(adt_def, variant) => {
+                adt_def.hash_stable(hcx, hasher);
+                variant.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct mir::VisibilityScopeData { span, parent_scope });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Operand<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            mir::Operand::Consume(ref lvalue) => {
+                lvalue.hash_stable(hcx, hasher);
+            }
+            mir::Operand::Constant(ref constant) => {
+                constant.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Rvalue<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            mir::Rvalue::Use(ref operand) => {
+                operand.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Repeat(ref operand, ref val) => {
+                operand.hash_stable(hcx, hasher);
+                val.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Ref(region, borrow_kind, ref lvalue) => {
+                region.hash_stable(hcx, hasher);
+                borrow_kind.hash_stable(hcx, hasher);
+                lvalue.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Len(ref lvalue) => {
+                lvalue.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Cast(cast_kind, ref operand, ty) => {
+                cast_kind.hash_stable(hcx, hasher);
+                operand.hash_stable(hcx, hasher);
+                ty.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::BinaryOp(op, ref operand1, ref operand2) |
+            mir::Rvalue::CheckedBinaryOp(op, ref operand1, ref operand2) => {
+                op.hash_stable(hcx, hasher);
+                operand1.hash_stable(hcx, hasher);
+                operand2.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::UnaryOp(op, ref operand) => {
+                op.hash_stable(hcx, hasher);
+                operand.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Discriminant(ref lvalue) => {
+                lvalue.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Box(ty) => {
+                ty.hash_stable(hcx, hasher);
+            }
+            mir::Rvalue::Aggregate(ref kind, ref operands) => {
+                kind.hash_stable(hcx, hasher);
+                operands.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(enum mir::CastKind {
+    Misc,
+    ReifyFnPointer,
+    ClosureFnPointer,
+    UnsafeFnPointer,
+    Unsize
+});
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::AggregateKind<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            mir::AggregateKind::Tuple => {}
+            mir::AggregateKind::Array(t) => {
+                t.hash_stable(hcx, hasher);
+            }
+            mir::AggregateKind::Adt(adt_def, idx, substs, active_field) => {
+                adt_def.hash_stable(hcx, hasher);
+                idx.hash_stable(hcx, hasher);
+                substs.hash_stable(hcx, hasher);
+                active_field.hash_stable(hcx, hasher);
+            }
+            mir::AggregateKind::Closure(def_id, ref substs) => {
+                def_id.hash_stable(hcx, hasher);
+                substs.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(enum mir::BinOp {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Rem,
+    BitXor,
+    BitAnd,
+    BitOr,
+    Shl,
+    Shr,
+    Eq,
+    Lt,
+    Le,
+    Ne,
+    Ge,
+    Gt
+});
+
+impl_stable_hash_for!(enum mir::UnOp {
+    Not,
+    Neg
+});
+
+
+impl_stable_hash_for!(struct mir::Constant<'tcx> { span, ty, literal });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for mir::Literal<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            mir::Literal::Item { def_id, substs } => {
+                def_id.hash_stable(hcx, hasher);
+                substs.hash_stable(hcx, hasher);
+            }
+            mir::Literal::Value { ref value } => {
+                value.hash_stable(hcx, hasher);
+            }
+            mir::Literal::Promoted { index } => {
+                index.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct mir::Location { block, statement_index });

src/librustc/ich/impls_syntax.rs

+// 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.
+
+//! This module contains `HashStable` implementations for various data types
+//! from libsyntax in no particular order.
+
+use ich::StableHashingContext;
+
+use std::hash as std_hash;
+use std::mem;
+
+use syntax::ast;
+use syntax::parse::token;
+use syntax::tokenstream;
+use syntax_pos::Span;
+
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHasherResult};
+use rustc_data_structures::accumulate_vec::AccumulateVec;
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ::syntax::symbol::InternedString {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let s: &str = &**self;
+        s.hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ast::Name {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        self.as_str().hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_for!(enum ::syntax::ast::AsmDialect {
+    Att,
+    Intel
+});
+
+impl_stable_hash_for!(enum ::syntax::ext::base::MacroKind {
+    Bang,
+    Attr,
+    Derive
+});
+
+
+impl_stable_hash_for!(enum ::syntax::abi::Abi {
+    Cdecl,
+    Stdcall,
+    Fastcall,
+    Vectorcall,
+    Aapcs,
+    Win64,
+    SysV64,
+    PtxKernel,
+    Msp430Interrupt,
+    X86Interrupt,
+    Rust,
+    C,
+    System,
+    RustIntrinsic,
+    RustCall,
+    PlatformIntrinsic,
+    Unadjusted
+});
+
+impl_stable_hash_for!(struct ::syntax::attr::Deprecation { since, note });
+impl_stable_hash_for!(struct ::syntax::attr::Stability { level, feature, rustc_depr });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ::syntax::attr::StabilityLevel {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ::syntax::attr::StabilityLevel::Unstable { ref reason, ref issue } => {
+                reason.hash_stable(hcx, hasher);
+                issue.hash_stable(hcx, hasher);
+            }
+            ::syntax::attr::StabilityLevel::Stable { ref since } => {
+                since.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct ::syntax::attr::RustcDeprecation { since, reason });
+
+
+impl_stable_hash_for!(enum ::syntax::attr::IntType {
+    SignedInt(int_ty),
+    UnsignedInt(uint_ty)
+});
+
+impl_stable_hash_for!(enum ::syntax::ast::LitIntType {
+    Signed(int_ty),
+    Unsigned(int_ty),
+    Unsuffixed
+});
+
+impl_stable_hash_for_spanned!(::syntax::ast::LitKind);
+impl_stable_hash_for!(enum ::syntax::ast::LitKind {
+    Str(value, style),
+    ByteStr(value),
+    Byte(value),
+    Char(value),
+    Int(value, lit_int_type),
+    Float(value, float_ty),
+    FloatUnsuffixed(value),
+    Bool(value)
+});
+
+impl_stable_hash_for!(enum ::syntax::ast::IntTy { Is, I8, I16, I32, I64, I128 });
+impl_stable_hash_for!(enum ::syntax::ast::UintTy { Us, U8, U16, U32, U64, U128 });
+impl_stable_hash_for!(enum ::syntax::ast::FloatTy { F32, F64 });
+impl_stable_hash_for!(enum ::syntax::ast::Unsafety { Unsafe, Normal });
+impl_stable_hash_for!(enum ::syntax::ast::Constness { Const, NotConst });
+impl_stable_hash_for!(enum ::syntax::ast::Defaultness { Default, Final });
+impl_stable_hash_for!(struct ::syntax::ast::Lifetime { id, span, name });
+impl_stable_hash_for!(enum ::syntax::ast::StrStyle { Cooked, Raw(pounds) });
+impl_stable_hash_for!(enum ::syntax::ast::AttrStyle { Outer, Inner });
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for [ast::Attribute] {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        // Some attributes are always ignored during hashing.
+        let filtered: AccumulateVec<[&ast::Attribute; 8]> = self
+            .iter()
+            .filter(|attr| {
+                !attr.is_sugared_doc &&
+                attr.name().map(|name| !hcx.is_ignored_attr(name)).unwrap_or(true)
+            })
+            .collect();
+
+        filtered.len().hash_stable(hcx, hasher);
+        for attr in filtered {
+            attr.hash_stable(hcx, hasher);
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ast::Attribute {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        // Make sure that these have been filtered out.
+        debug_assert!(self.name().map(|name| !hcx.is_ignored_attr(name)).unwrap_or(true));
+        debug_assert!(!self.is_sugared_doc);
+
+        let ast::Attribute {
+            id: _,
+            style,
+            ref path,
+            ref tokens,
+            is_sugared_doc: _,
+            span,
+        } = *self;
+
+        style.hash_stable(hcx, hasher);
+        path.segments.len().hash_stable(hcx, hasher);
+        for segment in &path.segments {
+            segment.identifier.name.hash_stable(hcx, hasher);
+        }
+        for tt in tokens.trees() {
+            tt.hash_stable(hcx, hasher);
+        }
+        span.hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for tokenstream::TokenTree {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            tokenstream::TokenTree::Token(span, ref token) => {
+                span.hash_stable(hcx, hasher);
+                hash_token(token, hcx, hasher, span);
+            }
+            tokenstream::TokenTree::Delimited(span, ref delimited) => {
+                span.hash_stable(hcx, hasher);
+                std_hash::Hash::hash(&delimited.delim, hasher);
+                for sub_tt in delimited.stream().trees() {
+                    sub_tt.hash_stable(hcx, hasher);
+                }
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for tokenstream::TokenStream {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        for sub_tt in self.trees() {
+            sub_tt.hash_stable(hcx, hasher);
+        }
+    }
+}
+
+fn hash_token<'a, 'tcx, W: StableHasherResult>(token: &token::Token,
+                                               hcx: &mut StableHashingContext<'a, 'tcx>,
+                                               hasher: &mut StableHasher<W>,
+                                               error_reporting_span: Span) {
+    mem::discriminant(token).hash_stable(hcx, hasher);
+    match *token {
+        token::Token::Eq |
+        token::Token::Lt |
+        token::Token::Le |
+        token::Token::EqEq |
+        token::Token::Ne |
+        token::Token::Ge |
+        token::Token::Gt |
+        token::Token::AndAnd |
+        token::Token::OrOr |
+        token::Token::Not |
+        token::Token::Tilde |
+        token::Token::At |
+        token::Token::Dot |
+        token::Token::DotDot |
+        token::Token::DotDotDot |
+        token::Token::Comma |
+        token::Token::Semi |
+        token::Token::Colon |
+        token::Token::ModSep |
+        token::Token::RArrow |
+        token::Token::LArrow |
+        token::Token::FatArrow |
+        token::Token::Pound |
+        token::Token::Dollar |
+        token::Token::Question |
+        token::Token::Underscore |
+        token::Token::Whitespace |
+        token::Token::Comment |
+        token::Token::Eof => {}
+
+        token::Token::BinOp(bin_op_token) |
+        token::Token::BinOpEq(bin_op_token) => {
+            std_hash::Hash::hash(&bin_op_token, hasher);
+        }
+
+        token::Token::OpenDelim(delim_token) |
+        token::Token::CloseDelim(delim_token) => {
+            std_hash::Hash::hash(&delim_token, hasher);
+        }
+        token::Token::Literal(ref lit, ref opt_name) => {
+            mem::discriminant(lit).hash_stable(hcx, hasher);
+            match *lit {
+                token::Lit::Byte(val) |
+                token::Lit::Char(val) |
+                token::Lit::Integer(val) |
+                token::Lit::Float(val) |
+                token::Lit::Str_(val) |
+                token::Lit::ByteStr(val) => val.hash_stable(hcx, hasher),
+                token::Lit::StrRaw(val, n) |
+                token::Lit::ByteStrRaw(val, n) => {
+                    val.hash_stable(hcx, hasher);
+                    n.hash_stable(hcx, hasher);
+                }
+            };
+            opt_name.hash_stable(hcx, hasher);
+        }
+
+        token::Token::Ident(ident) |
+        token::Token::Lifetime(ident) |
+        token::Token::SubstNt(ident) => ident.name.hash_stable(hcx, hasher),
+
+        token::Token::Interpolated(ref non_terminal) => {
+            // FIXME(mw): This could be implemented properly. It's just a
+            //            lot of work, since we would need to hash the AST
+            //            in a stable way, in addition to the HIR.
+            //            Since this is hardly used anywhere, just emit a
+            //            warning for now.
+            if hcx.tcx().sess.opts.debugging_opts.incremental.is_some() {
+                let msg = format!("Quasi-quoting might make incremental \
+                                   compilation very inefficient: {:?}",
+                                  non_terminal);
+                hcx.tcx().sess.span_warn(error_reporting_span, &msg[..]);
+            }
+
+            std_hash::Hash::hash(non_terminal, hasher);
+        }
+
+        token::Token::DocComment(val) |
+        token::Token::Shebang(val) => val.hash_stable(hcx, hasher),
+    }
+}

src/librustc/ich/impls_ty.rs

+// 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.
+
+//! This module contains `HashStable` implementations for various data types
+//! from rustc::ty in no particular order.
+
+use ich::StableHashingContext;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHasherResult};
+use std::hash as std_hash;
+use std::mem;
+use ty;
+
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::Ty<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let type_hash = hcx.tcx().type_id_hash(*self);
+        type_hash.hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_for!(struct ty::ItemSubsts<'tcx> { substs });
+
+impl<'a, 'tcx, T> HashStable<StableHashingContext<'a, 'tcx>> for ty::Slice<T>
+    where T: HashStable<StableHashingContext<'a, 'tcx>> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        (&**self).hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::subst::Kind<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        self.as_type().hash_stable(hcx, hasher);
+        self.as_region().hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::Region {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ty::ReErased |
+            ty::ReStatic |
+            ty::ReEmpty => {
+                // No variant fields to hash for these ...
+            }
+            ty::ReLateBound(db, ty::BrAnon(i)) => {
+                db.depth.hash_stable(hcx, hasher);
+                i.hash_stable(hcx, hasher);
+            }
+            ty::ReEarlyBound(ty::EarlyBoundRegion { index, name }) => {
+                index.hash_stable(hcx, hasher);
+                name.hash_stable(hcx, hasher);
+            }
+            ty::ReLateBound(..) |
+            ty::ReFree(..) |
+            ty::ReScope(..) |
+            ty::ReVar(..) |
+            ty::ReSkolemized(..) => {
+                bug!("TypeIdHasher: unexpected region {:?}", *self)
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::adjustment::AutoBorrow<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ty::adjustment::AutoBorrow::Ref(ref region, mutability) => {
+                region.hash_stable(hcx, hasher);
+                mutability.hash_stable(hcx, hasher);
+            }
+            ty::adjustment::AutoBorrow::RawPtr(mutability) => {
+                mutability.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::adjustment::Adjust<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ty::adjustment::Adjust::NeverToAny |
+            ty::adjustment::Adjust::ReifyFnPointer |
+            ty::adjustment::Adjust::UnsafeFnPointer |
+            ty::adjustment::Adjust::ClosureFnPointer |
+            ty::adjustment::Adjust::MutToConstPointer => {}
+            ty::adjustment::Adjust::DerefRef { autoderefs, ref autoref, unsize } => {
+                autoderefs.hash_stable(hcx, hasher);
+                autoref.hash_stable(hcx, hasher);
+                unsize.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct ty::adjustment::Adjustment<'tcx> { kind, target });
+impl_stable_hash_for!(struct ty::MethodCall { expr_id, autoderef });
+impl_stable_hash_for!(struct ty::MethodCallee<'tcx> { def_id, ty, substs });
+impl_stable_hash_for!(struct ty::UpvarId { var_id, closure_expr_id });
+impl_stable_hash_for!(struct ty::UpvarBorrow<'tcx> { kind, region });
+
+impl_stable_hash_for!(enum ty::BorrowKind {
+    ImmBorrow,
+    UniqueImmBorrow,
+    MutBorrow
+});
+
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::UpvarCapture<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ty::UpvarCapture::ByValue => {}
+            ty::UpvarCapture::ByRef(ref up_var_borrow) => {
+                up_var_borrow.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct ty::FnSig<'tcx> {
+    inputs_and_output,
+    variadic,
+    unsafety,
+    abi
+});
+
+impl<'a, 'tcx, T> HashStable<StableHashingContext<'a, 'tcx>> for ty::Binder<T>
+    where T: HashStable<StableHashingContext<'a, 'tcx>> + ty::fold::TypeFoldable<'tcx>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        hcx.tcx().anonymize_late_bound_regions(self).0.hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_for!(enum ty::ClosureKind { Fn, FnMut, FnOnce });
+
+impl_stable_hash_for!(enum ty::Visibility {
+    Public,
+    Restricted(def_id),
+    Invisible
+});
+
+impl_stable_hash_for!(struct ty::TraitRef<'tcx> { def_id, substs });
+impl_stable_hash_for!(struct ty::TraitPredicate<'tcx> { trait_ref });
+impl_stable_hash_for!(tuple_struct ty::EquatePredicate<'tcx> { t1, t2 });
+
+impl<'a, 'tcx, A, B> HashStable<StableHashingContext<'a, 'tcx>> for ty::OutlivesPredicate<A, B>
+    where A: HashStable<StableHashingContext<'a, 'tcx>>,
+          B: HashStable<StableHashingContext<'a, 'tcx>>,
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let ty::OutlivesPredicate(ref a, ref b) = *self;
+        a.hash_stable(hcx, hasher);
+        b.hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_for!(struct ty::ProjectionPredicate<'tcx> { projection_ty, ty });
+impl_stable_hash_for!(struct ty::ProjectionTy<'tcx> { trait_ref, item_name });
+
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::Predicate<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            ty::Predicate::Trait(ref pred) => {
+                pred.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::Equate(ref pred) => {
+                pred.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::RegionOutlives(ref pred) => {
+                pred.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::TypeOutlives(ref pred) => {
+                pred.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::Projection(ref pred) => {
+                pred.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::WellFormed(ty) => {
+                ty.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::ObjectSafe(def_id) => {
+                def_id.hash_stable(hcx, hasher);
+            }
+            ty::Predicate::ClosureKind(def_id, closure_kind) => {
+                def_id.hash_stable(hcx, hasher);
+                closure_kind.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::AdtFlags {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        std_hash::Hash::hash(self, hasher);
+    }
+}
+
+impl_stable_hash_for!(struct ty::VariantDef {
+    did,
+    name,
+    discr,
+    fields,
+    ctor_kind
+});
+
+impl_stable_hash_for!(enum ty::VariantDiscr {
+    Explicit(def_id),
+    Relative(distance)
+});
+
+impl_stable_hash_for!(struct ty::FieldDef {
+    did,
+    name,
+    vis
+});
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>>
+for ::middle::const_val::ConstVal<'tcx> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use middle::const_val::ConstVal;
+
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            ConstVal::Float(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Integral(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Str(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::ByteStr(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Bool(value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Function(def_id, substs) => {
+                def_id.hash_stable(hcx, hasher);
+                substs.hash_stable(hcx, hasher);
+            }
+            ConstVal::Struct(ref _name_value_map) => {
+                // BTreeMap<ast::Name, ConstVal<'tcx>>),
+                panic!("Ordering still unstable")
+            }
+            ConstVal::Tuple(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Array(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+            ConstVal::Repeat(ref value, times) => {
+                value.hash_stable(hcx, hasher);
+                times.hash_stable(hcx, hasher);
+            }
+            ConstVal::Char(value) => {
+                value.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(struct ty::ClosureSubsts<'tcx> { substs });
+
+
+impl_stable_hash_for!(struct ty::GenericPredicates<'tcx> {
+    parent,
+    predicates
+});
+
+impl_stable_hash_for!(enum ty::Variance {
+    Covariant,
+    Invariant,
+    Contravariant,
+    Bivariant
+});
+
+impl_stable_hash_for!(enum ty::adjustment::CustomCoerceUnsized {
+    Struct(index)
+});
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::Generics {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let ty::Generics {
+            parent,
+            parent_regions,
+            parent_types,
+            ref regions,
+            ref types,
+
+            // Reverse map to each `TypeParameterDef`'s `index` field, from
+            // `def_id.index` (`def_id.krate` is the same as the item's).
+            type_param_to_index: _, // Don't hash this
+            has_self,
+        } = *self;
+
+        parent.hash_stable(hcx, hasher);
+        parent_regions.hash_stable(hcx, hasher);
+        parent_types.hash_stable(hcx, hasher);
+        regions.hash_stable(hcx, hasher);
+        types.hash_stable(hcx, hasher);
+        has_self.hash_stable(hcx, hasher);
+    }
+}
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::RegionParameterDef {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let ty::RegionParameterDef {
+            name,
+            def_id,
+            index,
+            issue_32330: _,
+            pure_wrt_drop
+        } = *self;
+
+        name.hash_stable(hcx, hasher);
+        def_id.hash_stable(hcx, hasher);
+        index.hash_stable(hcx, hasher);
+        pure_wrt_drop.hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_for!(struct ty::TypeParameterDef {
+    name,
+    def_id,
+    index,
+    has_default,
+    object_lifetime_default,
+    pure_wrt_drop
+});
+
+
+impl<'a, 'tcx, T> HashStable<StableHashingContext<'a, 'tcx>>
+for ::middle::resolve_lifetime::Set1<T>
+    where T: HashStable<StableHashingContext<'a, 'tcx>>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        use middle::resolve_lifetime::Set1;
+
+        mem::discriminant(self).hash_stable(hcx, hasher);
+        match *self {
+            Set1::Empty |
+            Set1::Many => {
+                // Nothing to do.
+            }
+            Set1::One(ref value) => {
+                value.hash_stable(hcx, hasher);
+            }
+        }
+    }
+}
+
+impl_stable_hash_for!(enum ::middle::resolve_lifetime::Region {
+    Static,
+    EarlyBound(index, decl),
+    LateBound(db_index, decl),
+    LateBoundAnon(db_index, anon_index),
+    Free(call_site_scope_data, decl)
+});
+
+impl_stable_hash_for!(struct ::middle::region::CallSiteScopeData {
+    fn_id,
+    body_id
+});
+
+impl_stable_hash_for!(struct ty::DebruijnIndex {
+    depth
+});

src/librustc/ich/mod.rs

@@ -8,13 +8,23 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+//! ICH - Incremental Compilation Hash
+
 pub use self::fingerprint::Fingerprint;
 pub use self::def_path_hash::DefPathHashes;
 pub use self::caching_codemap_view::CachingCodemapView;
+pub use self::hcx::{StableHashingContext, NodeIdHashingMode};
 
 mod fingerprint;
 mod def_path_hash;
 mod caching_codemap_view;
+mod hcx;
+
+mod impls_const_math;
+mod impls_hir;
+mod impls_mir;
+mod impls_ty;
+mod impls_syntax;
 
 pub const ATTR_DIRTY: &'static str = "rustc_dirty";
 pub const ATTR_CLEAN: &'static str = "rustc_clean";
@@ -22,6 +32,20 @@
 pub const ATTR_CLEAN_METADATA: &'static str = "rustc_metadata_clean";
 pub const ATTR_IF_THIS_CHANGED: &'static str = "rustc_if_this_changed";
 pub const ATTR_THEN_THIS_WOULD_NEED: &'static str = "rustc_then_this_would_need";
+pub const ATTR_PARTITION_REUSED: &'static str = "rustc_partition_reused";
+pub const ATTR_PARTITION_TRANSLATED: &'static str = "rustc_partition_translated";
+
+
+pub const DEP_GRAPH_ASSERT_ATTRS: &'static [&'static str] = &[
+    ATTR_IF_THIS_CHANGED,
+    ATTR_THEN_THIS_WOULD_NEED,
+    ATTR_DIRTY,
+    ATTR_CLEAN,
+    ATTR_DIRTY_METADATA,
+    ATTR_CLEAN_METADATA,
+    ATTR_PARTITION_REUSED,
+    ATTR_PARTITION_TRANSLATED,
+];
 
 pub const IGNORED_ATTRIBUTES: &'static [&'static str] = &[
     "cfg",
@@ -30,5 +54,7 @@
     ATTR_DIRTY,
     ATTR_CLEAN,
     ATTR_DIRTY_METADATA,
-    ATTR_CLEAN_METADATA
+    ATTR_CLEAN_METADATA,
+    ATTR_PARTITION_REUSED,
+    ATTR_PARTITION_TRANSLATED,
 ];

src/librustc/lib.rs

@@ -41,6 +41,7 @@
 #![feature(specialization)]
 #![feature(staged_api)]
 #![feature(unboxed_closures)]
+#![feature(discriminant_value)]
 
 extern crate arena;
 extern crate core;

src/librustc/macros.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// ignore-tidy-linelength
+
 macro_rules! enum_from_u32 {
     ($(#[$attr:meta])* pub enum $name:ident {
         $($variant:ident = $e:expr,)*
@@ -59,3 +61,80 @@ pub fn from_u32(u: u32) -> Option<$name> {
         $crate::session::span_bug_fmt(file!(), line!(), $span, format_args!($($message)*))
     })
 }
+
+#[macro_export]
+macro_rules! __impl_stable_hash_field {
+    (DECL IGNORED) => (_);
+    (DECL $name:ident) => (ref $name);
+    (USE IGNORED $ctx:expr, $hasher:expr) => ({});
+    (USE $name:ident, $ctx:expr, $hasher:expr) => ($name.hash_stable($ctx, $hasher));
+}
+
+#[macro_export]
+macro_rules! impl_stable_hash_for {
+    (enum $enum_name:path { $( $variant:ident $( ( $($arg:ident),* ) )* ),* }) => {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx>> for $enum_name {
+            #[inline]
+            fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx>,
+                                                  __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
+                use $enum_name::*;
+                ::std::mem::discriminant(self).hash_stable(__ctx, __hasher);
+
+                match *self {
+                    $(
+                        $variant $( ( $( __impl_stable_hash_field!(DECL $arg) ),* ) )* => {
+                            $($( __impl_stable_hash_field!(USE $arg, __ctx, __hasher) );*)*
+                        }
+                    )*
+                }
+            }
+        }
+    };
+    (struct $struct_name:path { $($field:ident),* }) => {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx>> for $struct_name {
+            #[inline]
+            fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx>,
+                                                  __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
+                let $struct_name {
+                    $(ref $field),*
+                } = *self;
+
+                $( $field.hash_stable(__ctx, __hasher));*
+            }
+        }
+    };
+    (tuple_struct $struct_name:path { $($field:ident),* }) => {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx>> for $struct_name {
+            #[inline]
+            fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx>,
+                                                  __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
+                let $struct_name (
+                    $(ref $field),*
+                ) = *self;
+
+                $( $field.hash_stable(__ctx, __hasher));*
+            }
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! impl_stable_hash_for_spanned {
+    ($T:path) => (
+
+        impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ::syntax::codemap::Spanned<$T>
+        {
+            #[inline]
+            fn hash_stable<W: StableHasherResult>(&self,
+                                                  hcx: &mut StableHashingContext<'a, 'tcx>,
+                                                  hasher: &mut StableHasher<W>) {
+                self.node.hash_stable(hcx, hasher);
+                self.span.hash_stable(hcx, hasher);
+            }
+        }
+    );
+}
+

src/librustc/mir/cache.rs

@@ -10,7 +10,9 @@
 
 use std::cell::{Ref, RefCell};
 use rustc_data_structures::indexed_vec::IndexVec;
-
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHasherResult};
+use ich::StableHashingContext;
 use mir::{Mir, BasicBlock};
 
 use rustc_serialize as serialize;
@@ -33,6 +35,13 @@ fn decode<D: serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
     }
 }
 
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for Cache {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _: &mut StableHashingContext<'a, 'tcx>,
+                                          _: &mut StableHasher<W>) {
+        // do nothing
+    }
+}
 
 impl Cache {
     pub fn new() -> Self {

src/librustc/mir/mod.rs

@@ -243,6 +243,19 @@ pub fn make_statement_nop(&mut self, location: Location) {
     }
 }
 
+impl_stable_hash_for!(struct Mir<'tcx> {
+    basic_blocks,
+    visibility_scopes,
+    promoted,
+    return_ty,
+    local_decls,
+    arg_count,
+    upvar_decls,
+    spread_arg,
+    span,
+    cache
+});
+
 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
     type Output = BasicBlockData<'tcx>;
 
@@ -830,6 +843,11 @@ pub struct Static<'tcx> {
     pub ty: Ty<'tcx>,
 }
 
+impl_stable_hash_for!(struct Static<'tcx> {
+    def_id,
+    ty
+});
+
 /// The `Projection` data structure defines things of the form `B.x`
 /// or `*B` or `B[index]`. Note that it is parameterized because it is
 /// shared between `Constant` and `Lvalue`. See the aliases

src/librustc/ty/mod.rs

@@ -19,6 +19,7 @@
 use hir::{map as hir_map, FreevarMap, TraitMap};
 use hir::def::{Def, CtorKind, ExportMap};
 use hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
+use ich::StableHashingContext;
 use middle::const_val::ConstVal;
 use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
 use middle::privacy::AccessLevels;
@@ -50,6 +51,8 @@
 use rustc_const_math::ConstInt;
 
 use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter;
+use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
+                                           HashStable};
 
 use hir;
 use hir::itemlikevisit::ItemLikeVisitor;
@@ -1379,6 +1382,25 @@ fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 
 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {}
 
+
+impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for AdtDef {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a, 'tcx>,
+                                          hasher: &mut StableHasher<W>) {
+        let ty::AdtDef {
+            did,
+            ref variants,
+            ref flags,
+            ref repr,
+        } = *self;
+
+        did.hash_stable(hcx, hasher);
+        variants.hash_stable(hcx, hasher);
+        flags.hash_stable(hcx, hasher);
+        repr.hash_stable(hcx, hasher);
+    }
+}
+
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum AdtKind { Struct, Union, Enum }
 
@@ -1391,6 +1413,13 @@ pub struct ReprOptions {
     pub int: Option<attr::IntType>,
 }
 
+impl_stable_hash_for!(struct ReprOptions {
+    c,
+    packed,
+    simd,
+    int
+});
+
 impl ReprOptions {
     pub fn new(tcx: TyCtxt, did: DefId) -> ReprOptions {
         let mut ret = ReprOptions::default();

src/librustc_data_structures/lib.rs

@@ -37,6 +37,8 @@
 #![feature(unsize)]
 #![feature(i128_type)]
 #![feature(conservative_impl_trait)]
+#![feature(discriminant_value)]
+#![feature(specialization)]
 
 #![cfg_attr(unix, feature(libc))]
 #![cfg_attr(test, feature(test))]

src/librustc_data_structures/stable_hasher.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::hash::Hasher;
+use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
 use blake2b::Blake2bHasher;
@@ -174,3 +174,193 @@ fn write_isize(&mut self, i: isize) {
         self.write_ileb128(i as i64);
     }
 }
+
+
+/// Something that implements `HashStable<CTX>` can be hashed in a way that is
+/// stable across multiple compiliation sessions.
+pub trait HashStable<CTX> {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut CTX,
+                                          hasher: &mut StableHasher<W>);
+}
+
+// Implement HashStable by just calling `Hash::hash()`. This works fine for
+// self-contained values that don't depend on the hashing context `CTX`.
+macro_rules! impl_stable_hash_via_hash {
+    ($t:ty) => (
+        impl<CTX> HashStable<CTX> for $t {
+            #[inline]
+            fn hash_stable<W: StableHasherResult>(&self,
+                                                  _: &mut CTX,
+                                                  hasher: &mut StableHasher<W>) {
+                ::std::hash::Hash::hash(self, hasher);
+            }
+        }
+    );
+}
+
+impl_stable_hash_via_hash!(i8);
+impl_stable_hash_via_hash!(i16);
+impl_stable_hash_via_hash!(i32);
+impl_stable_hash_via_hash!(i64);
+impl_stable_hash_via_hash!(isize);
+
+impl_stable_hash_via_hash!(u8);
+impl_stable_hash_via_hash!(u16);
+impl_stable_hash_via_hash!(u32);
+impl_stable_hash_via_hash!(u64);
+impl_stable_hash_via_hash!(usize);
+
+impl_stable_hash_via_hash!(u128);
+impl_stable_hash_via_hash!(i128);
+
+impl_stable_hash_via_hash!(char);
+impl_stable_hash_via_hash!(());
+
+impl<CTX> HashStable<CTX> for f32 {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        let val: u32 = unsafe {
+            ::std::mem::transmute(*self)
+        };
+        val.hash_stable(ctx, hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for f64 {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        let val: u64 = unsafe {
+            ::std::mem::transmute(*self)
+        };
+        val.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T1: HashStable<CTX>, T2: HashStable<CTX>, CTX> HashStable<CTX> for (T1, T2) {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        self.0.hash_stable(ctx, hasher);
+        self.1.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T: HashStable<CTX>, CTX> HashStable<CTX> for [T] {
+    default fn hash_stable<W: StableHasherResult>(&self,
+                                                  ctx: &mut CTX,
+                                                  hasher: &mut StableHasher<W>) {
+        self.len().hash_stable(ctx, hasher);
+        for item in self {
+            item.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<T: HashStable<CTX>, CTX> HashStable<CTX> for Vec<T> {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        (&self[..]).hash_stable(ctx, hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for str {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        self.len().hash(hasher);
+        self.as_bytes().hash(hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for bool {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        (if *self { 1u8 } else { 0u8 }).hash_stable(ctx, hasher);
+    }
+}
+
+
+impl<T, CTX> HashStable<CTX> for Option<T>
+    where T: HashStable<CTX>
+{
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        if let Some(ref value) = *self {
+            1u8.hash_stable(ctx, hasher);
+            value.hash_stable(ctx, hasher);
+        } else {
+            0u8.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<'a, T, CTX> HashStable<CTX> for &'a T
+    where T: HashStable<CTX>
+{
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        (**self).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for ::std::mem::Discriminant<T> {
+    #[inline]
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        ::std::hash::Hash::hash(self, hasher);
+    }
+}
+
+impl<K, V, CTX> HashStable<CTX> for ::std::collections::BTreeMap<K, V>
+    where K: Ord + HashStable<CTX>,
+          V: HashStable<CTX>,
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        self.len().hash_stable(ctx, hasher);
+        for (k, v) in self {
+            k.hash_stable(ctx, hasher);
+            v.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for ::std::collections::BTreeSet<T>
+    where T: Ord + HashStable<CTX>,
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        self.len().hash_stable(ctx, hasher);
+        for v in self {
+            v.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<I: ::indexed_vec::Idx, T, CTX> HashStable<CTX> for ::indexed_vec::IndexVec<I, T>
+    where T: HashStable<CTX>,
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          ctx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        self.len().hash_stable(ctx, hasher);
+        for v in &self.raw {
+            v.hash_stable(ctx, hasher);
+        }
+    }
+}

src/librustc_incremental/calculate_svh/mod.rs

@@ -27,24 +27,17 @@
 //! at the end of compilation would be different from those computed
 //! at the beginning.
 
-use syntax::ast;
 use std::cell::RefCell;
 use std::hash::Hash;
 use rustc::dep_graph::DepNode;
 use rustc::hir;
 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
-use rustc::hir::intravisit as visit;
-use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
-use rustc::ich::{Fingerprint, DefPathHashes, CachingCodemapView};
+use rustc::hir::itemlikevisit::ItemLikeVisitor;
+use rustc::ich::{Fingerprint, StableHashingContext};
 use rustc::ty::TyCtxt;
-use rustc_data_structures::stable_hasher::StableHasher;
+use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 use rustc_data_structures::fx::FxHashMap;
 use rustc::util::common::record_time;
-use rustc::session::config::DebugInfoLevel::NoDebugInfo;
-
-use self::svh_visitor::StrictVersionHashVisitor;
-
-mod svh_visitor;
 
 pub type IchHasher = StableHasher<Fingerprint>;
 
@@ -94,91 +87,42 @@ fn index(&self, index: &'a DepNode<DefId>) -> &Fingerprint {
     }
 }
 
-
-pub fn compute_incremental_hashes_map<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
-                                                    -> IncrementalHashesMap {
-    let _ignore = tcx.dep_graph.in_ignore();
-    let krate = tcx.hir.krate();
-    let hash_spans = tcx.sess.opts.debuginfo != NoDebugInfo;
-    let mut visitor = HashItemsVisitor {
-        tcx: tcx,
-        hashes: IncrementalHashesMap::new(),
-        def_path_hashes: DefPathHashes::new(tcx),
-        codemap: CachingCodemapView::new(tcx),
-        hash_spans: hash_spans,
-    };
-    record_time(&tcx.sess.perf_stats.incr_comp_hashes_time, || {
-        visitor.calculate_def_id(DefId::local(CRATE_DEF_INDEX), |v| {
-            v.hash_crate_root_module(krate);
-        });
-        krate.visit_all_item_likes(&mut visitor.as_deep_visitor());
-
-        for macro_def in krate.exported_macros.iter() {
-            visitor.calculate_node_id(macro_def.id,
-                                      |v| v.visit_macro_def(macro_def));
-        }
-    });
-
-    tcx.sess.perf_stats.incr_comp_hashes_count.set(visitor.hashes.len() as u64);
-
-    record_time(&tcx.sess.perf_stats.svh_time, || visitor.compute_crate_hash());
-    visitor.hashes
-}
-
-struct HashItemsVisitor<'a, 'tcx: 'a> {
-    tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    def_path_hashes: DefPathHashes<'a, 'tcx>,
-    codemap: CachingCodemapView<'tcx>,
+struct ComputeItemHashesVisitor<'a, 'tcx: 'a> {
+    hcx: StableHashingContext<'a, 'tcx>,
     hashes: IncrementalHashesMap,
-    hash_spans: bool,
 }
 
-impl<'a, 'tcx> HashItemsVisitor<'a, 'tcx> {
-    fn calculate_node_id<W>(&mut self, id: ast::NodeId, walk_op: W)
-        where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
-    {
-        let def_id = self.tcx.hir.local_def_id(id);
-        self.calculate_def_id(def_id, walk_op)
-    }
-
-    fn calculate_def_id<W>(&mut self, def_id: DefId, mut walk_op: W)
-        where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
+impl<'a, 'tcx: 'a> ComputeItemHashesVisitor<'a, 'tcx> {
+    fn compute_and_store_ich_for_item_like<T>(&mut self,
+                                              dep_node: DepNode<DefId>,
+                                              hash_bodies: bool,
+                                              item_like: T)
+        where T: HashStable<StableHashingContext<'a, 'tcx>>
     {
-        assert!(def_id.is_local());
-        debug!("HashItemsVisitor::calculate(def_id={:?})", def_id);
-        self.calculate_def_hash(DepNode::Hir(def_id), false, &mut walk_op);
-        self.calculate_def_hash(DepNode::HirBody(def_id), true, &mut walk_op);
-    }
+        let mut hasher = IchHasher::new();
+        self.hcx.while_hashing_hir_bodies(hash_bodies, |hcx| {
+            item_like.hash_stable(hcx, &mut hasher);
+        });
 
-    fn calculate_def_hash<W>(&mut self,
-                             dep_node: DepNode<DefId>,
-                             hash_bodies: bool,
-                             walk_op: &mut W)
-        where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
-    {
-        let mut state = IchHasher::new();
-        walk_op(&mut StrictVersionHashVisitor::new(&mut state,
-                                                   self.tcx,
-                                                   &mut self.def_path_hashes,
-                                                   &mut self.codemap,
-                                                   self.hash_spans,
-                                                   hash_bodies));
-        let bytes_hashed = state.bytes_hashed();
-        let item_hash = state.finish();
+        let bytes_hashed = hasher.bytes_hashed();
+        let item_hash = hasher.finish();
         debug!("calculate_def_hash: dep_node={:?} hash={:?}", dep_node, item_hash);
         self.hashes.insert(dep_node, item_hash);
 
-        let bytes_hashed = self.tcx.sess.perf_stats.incr_comp_bytes_hashed.get() +
+        let tcx = self.hcx.tcx();
+        let bytes_hashed =
+            tcx.sess.perf_stats.incr_comp_bytes_hashed.get() +
             bytes_hashed;
-        self.tcx.sess.perf_stats.incr_comp_bytes_hashed.set(bytes_hashed);
+        tcx.sess.perf_stats.incr_comp_bytes_hashed.set(bytes_hashed);
     }
 
     fn compute_crate_hash(&mut self) {
-        let krate = self.tcx.hir.krate();
+        let tcx = self.hcx.tcx();
+        let krate = tcx.hir.krate();
 
         let mut crate_state = IchHasher::new();
 
-        let crate_disambiguator = self.tcx.sess.local_crate_disambiguator();
+        let crate_disambiguator = tcx.sess.local_crate_disambiguator();
         "crate_disambiguator".hash(&mut crate_state);
         crate_disambiguator.as_str().len().hash(&mut crate_state);
         crate_disambiguator.as_str().hash(&mut crate_state);
@@ -186,7 +130,7 @@ fn compute_crate_hash(&mut self) {
         // add each item (in some deterministic order) to the overall
         // crate hash.
         {
-            let def_path_hashes = &mut self.def_path_hashes;
+            let hcx = &mut self.hcx;
             let mut item_hashes: Vec<_> =
                 self.hashes.iter()
                            .map(|(item_dep_node, &item_hash)| {
@@ -194,7 +138,7 @@ fn compute_crate_hash(&mut self) {
                                // DepNode<u64> where the u64 is the
                                // hash of the def-id's def-path:
                                let item_dep_node =
-                                   item_dep_node.map_def(|&did| Some(def_path_hashes.hash(did)))
+                                   item_dep_node.map_def(|&did| Some(hcx.def_path_hash(did)))
                                                 .unwrap();
                                (item_dep_node, item_hash)
                            })
@@ -203,40 +147,85 @@ fn compute_crate_hash(&mut self) {
             item_hashes.hash(&mut crate_state);
         }
 
-        {
-            let mut visitor = StrictVersionHashVisitor::new(&mut crate_state,
-                                                            self.tcx,
-                                                            &mut self.def_path_hashes,
-                                                            &mut self.codemap,
-                                                            self.hash_spans,
-                                                            false);
-            visitor.hash_attributes(&krate.attrs);
-        }
+        krate.attrs.hash_stable(&mut self.hcx, &mut crate_state);
 
         let crate_hash = crate_state.finish();
         self.hashes.insert(DepNode::Krate, crate_hash);
         debug!("calculate_crate_hash: crate_hash={:?}", crate_hash);
     }
-}
 
-
-impl<'a, 'tcx> Visitor<'tcx> for HashItemsVisitor<'a, 'tcx> {
-    fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
-        NestedVisitorMap::None
+    fn hash_crate_root_module(&mut self, krate: &'tcx hir::Crate) {
+        let hir::Crate {
+            ref module,
+            // Crate attributes are not copied over to the root `Mod`, so hash
+            // them explicitly here.
+            ref attrs,
+            span,
+
+            // These fields are handled separately:
+            exported_macros: _,
+            items: _,
+            trait_items: _,
+            impl_items: _,
+            bodies: _,
+            trait_impls: _,
+            trait_default_impl: _,
+            body_ids: _,
+        } = *krate;
+
+        let def_id = DefId::local(CRATE_DEF_INDEX);
+        self.compute_and_store_ich_for_item_like(DepNode::Hir(def_id),
+                                                 false,
+                                                 (module, (span, attrs)));
+        self.compute_and_store_ich_for_item_like(DepNode::HirBody(def_id),
+                                                 true,
+                                                 (module, (span, attrs)));
     }
+}
 
+impl<'a, 'tcx: 'a> ItemLikeVisitor<'tcx> for ComputeItemHashesVisitor<'a, 'tcx> {
     fn visit_item(&mut self, item: &'tcx hir::Item) {
-        self.calculate_node_id(item.id, |v| v.visit_item(item));
-        visit::walk_item(self, item);
+        let def_id = self.hcx.tcx().hir.local_def_id(item.id);
+        self.compute_and_store_ich_for_item_like(DepNode::Hir(def_id), false, item);
+        self.compute_and_store_ich_for_item_like(DepNode::HirBody(def_id), true, item);
     }
 
-    fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
-        self.calculate_node_id(trait_item.id, |v| v.visit_trait_item(trait_item));
-        visit::walk_trait_item(self, trait_item);
+    fn visit_trait_item(&mut self, item: &'tcx hir::TraitItem) {
+        let def_id = self.hcx.tcx().hir.local_def_id(item.id);
+        self.compute_and_store_ich_for_item_like(DepNode::Hir(def_id), false, item);
+        self.compute_and_store_ich_for_item_like(DepNode::HirBody(def_id), true, item);
     }
 
-    fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
-        self.calculate_node_id(impl_item.id, |v| v.visit_impl_item(impl_item));
-        visit::walk_impl_item(self, impl_item);
+    fn visit_impl_item(&mut self, item: &'tcx hir::ImplItem) {
+        let def_id = self.hcx.tcx().hir.local_def_id(item.id);
+        self.compute_and_store_ich_for_item_like(DepNode::Hir(def_id), false, item);
+        self.compute_and_store_ich_for_item_like(DepNode::HirBody(def_id), true, item);
     }
 }
+
+pub fn compute_incremental_hashes_map<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
+                                                    -> IncrementalHashesMap {
+    let _ignore = tcx.dep_graph.in_ignore();
+    let krate = tcx.hir.krate();
+
+    let mut visitor = ComputeItemHashesVisitor {
+        hcx: StableHashingContext::new(tcx),
+        hashes: IncrementalHashesMap::new(),
+    };
+
+    record_time(&tcx.sess.perf_stats.incr_comp_hashes_time, || {
+        visitor.hash_crate_root_module(krate);
+        krate.visit_all_item_likes(&mut visitor);
+
+        for macro_def in krate.exported_macros.iter() {
+            let def_id = tcx.hir.local_def_id(macro_def.id);
+            visitor.compute_and_store_ich_for_item_like(DepNode::Hir(def_id), false, macro_def);
+            visitor.compute_and_store_ich_for_item_like(DepNode::HirBody(def_id), true, macro_def);
+        }
+    });
+
+    tcx.sess.perf_stats.incr_comp_hashes_count.set(visitor.hashes.len() as u64);
+
+    record_time(&tcx.sess.perf_stats.svh_time, || visitor.compute_crate_hash());
+    visitor.hashes
+}

src/librustc_incremental/lib.rs

@@ -22,7 +22,6 @@
 #![feature(rustc_private)]
 #![feature(staged_api)]
 #![feature(rand)]
-#![feature(core_intrinsics)]
 #![feature(conservative_impl_trait)]
 #![cfg_attr(stage0, feature(pub_restricted))]
 

src/librustc_trans/assert_module_sources.rs

@@ -32,8 +32,7 @@
 
 use {ModuleSource, ModuleTranslation};
 
-const PARTITION_REUSED: &'static str = "rustc_partition_reused";
-const PARTITION_TRANSLATED: &'static str = "rustc_partition_translated";
+use rustc::ich::{ATTR_PARTITION_REUSED, ATTR_PARTITION_TRANSLATED};
 
 const MODULE: &'static str = "module";
 const CFG: &'static str = "cfg";
@@ -62,9 +61,9 @@ struct AssertModuleSource<'a, 'tcx: 'a> {
 
 impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
     fn check_attr(&self, attr: &ast::Attribute) {
-        let disposition = if attr.check_name(PARTITION_REUSED) {
+        let disposition = if attr.check_name(ATTR_PARTITION_REUSED) {
             Disposition::Reused
-        } else if attr.check_name(PARTITION_TRANSLATED) {
+        } else if attr.check_name(ATTR_PARTITION_TRANSLATED) {
             Disposition::Translated
         } else {
             return;

src/libsyntax/ptr.rs

@@ -43,6 +43,8 @@
 
 use serialize::{Encodable, Decodable, Encoder, Decoder};
 
+use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
+                                           HashStable};
 /// An owned smart pointer.
 #[derive(Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub struct P<T: ?Sized> {
@@ -215,3 +217,13 @@ fn decode<D: Decoder>(d: &mut D) -> Result<P<[T]>, D::Error> {
         }))
     }
 }
+
+impl<CTX, T> HashStable<CTX> for P<T>
+    where T: ?Sized + HashStable<CTX>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        (**self).hash_stable(hcx, hasher);
+    }
+}

src/libsyntax/util/rc_slice.rs

@@ -12,6 +12,9 @@
 use std::ops::Deref;
 use std::rc::Rc;
 
+use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
+                                           HashStable};
+
 #[derive(Clone)]
 pub struct RcSlice<T> {
     data: Rc<Box<[T]>>,
@@ -41,3 +44,13 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(self.deref(), f)
     }
 }
+
+impl<CTX, T> HashStable<CTX> for RcSlice<T>
+    where T: HashStable<CTX>
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut CTX,
+                                          hasher: &mut StableHasher<W>) {
+        (**self).hash_stable(hcx, hasher);
+    }
+}