Auto merge of #89266 - cjgillot:session-ich, r=michaelwoerister

Move ICH to rustc_query_system

Based on https://github.com/rust-lang/rust/pull/89183

The StableHashingContext does not need to be in rustc_middle.

This PR moves it to rustc_query_system. This will avoid a dependency between rustc_ast_lowering and rustc_middle in https://github.com/rust-lang/rust/pull/89124.

74 files changed, 152 insertions, 216 deletions

diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 0ab452fb42d..8d7f2b65c5a 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -66,7 +66,7 @@ fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug)]
+#[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum InlineAttr {
     None,
     Hint,
@@ -74,13 +74,13 @@ pub enum InlineAttr {
     Never,
 }
 
-#[derive(Clone, Encodable, Decodable, Debug, PartialEq, Eq)]
+#[derive(Clone, Encodable, Decodable, Debug, PartialEq, Eq, HashStable_Generic)]
 pub enum InstructionSetAttr {
     ArmA32,
     ArmT32,
 }
 
-#[derive(Clone, Encodable, Decodable, Debug)]
+#[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum OptimizeAttr {
     None,
     Speed,
diff --git a/compiler/rustc_codegen_cranelift/src/archive.rs b/compiler/rustc_codegen_cranelift/src/archive.rs
index 8a1f6543990..71f510c037f 100644
--- a/compiler/rustc_codegen_cranelift/src/archive.rs
+++ b/compiler/rustc_codegen_cranelift/src/archive.rs
@@ -242,7 +242,7 @@ impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
     fn inject_dll_import_lib(
         &mut self,
         _lib_name: &str,
-        _dll_imports: &[rustc_middle::middle::cstore::DllImport],
+        _dll_imports: &[rustc_session::cstore::DllImport],
         _tmpdir: &rustc_data_structures::temp_dir::MaybeTempDir,
     ) {
         bug!("injecting dll imports is not supported");
diff --git a/compiler/rustc_codegen_gcc/src/archive.rs b/compiler/rustc_codegen_gcc/src/archive.rs
index d749d763402..11dd6d49aa7 100644
--- a/compiler/rustc_codegen_gcc/src/archive.rs
+++ b/compiler/rustc_codegen_gcc/src/archive.rs
@@ -1,12 +1,11 @@
 use std::fs::File;
 use std::path::{Path, PathBuf};
 
-use rustc_session::Session;
 use rustc_codegen_ssa::back::archive::ArchiveBuilder;
+use rustc_session::Session;
 
 use rustc_data_structures::temp_dir::MaybeTempDir;
-use rustc_middle::middle::cstore::DllImport;
-
+use rustc_session::cstore::DllImport;
 
 struct ArchiveConfig<'a> {
     sess: &'a Session,
diff --git a/compiler/rustc_codegen_llvm/Cargo.toml b/compiler/rustc_codegen_llvm/Cargo.toml
index 3f024434581..a6a553b31a3 100644
--- a/compiler/rustc_codegen_llvm/Cargo.toml
+++ b/compiler/rustc_codegen_llvm/Cargo.toml
@@ -26,6 +26,7 @@ rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_llvm = { path = "../rustc_llvm" }
 rustc_metadata = { path = "../rustc_metadata" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_session = { path = "../rustc_session" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_target = { path = "../rustc_target" }
diff --git a/compiler/rustc_codegen_llvm/src/back/archive.rs b/compiler/rustc_codegen_llvm/src/back/archive.rs
index 4e86946219f..ebc3b704158 100644
--- a/compiler/rustc_codegen_llvm/src/back/archive.rs
+++ b/compiler/rustc_codegen_llvm/src/back/archive.rs
@@ -11,7 +11,7 @@ use crate::llvm::archive_ro::{ArchiveRO, Child};
 use crate::llvm::{self, ArchiveKind, LLVMMachineType, LLVMRustCOFFShortExport};
 use rustc_codegen_ssa::back::archive::ArchiveBuilder;
 use rustc_data_structures::temp_dir::MaybeTempDir;
-use rustc_middle::middle::cstore::{DllCallingConvention, DllImport};
+use rustc_session::cstore::{DllCallingConvention, DllImport};
 use rustc_session::Session;
 
 struct ArchiveConfig<'a> {
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index f6ec5e6395f..8e6a66a6175 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -26,13 +26,13 @@ use rustc_fs_util::path_to_c_string;
 use rustc_hir::def::CtorKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_index::vec::{Idx, IndexVec};
-use rustc_middle::ich::NodeIdHashingMode;
 use rustc_middle::mir::{self, GeneratorLayout};
 use rustc_middle::ty::layout::{self, IntegerExt, LayoutOf, PrimitiveExt, TyAndLayout};
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::Instance;
 use rustc_middle::ty::{self, AdtKind, GeneratorSubsts, ParamEnv, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
+use rustc_query_system::ich::NodeIdHashingMode;
 use rustc_session::config::{self, DebugInfo};
 use rustc_span::symbol::Symbol;
 use rustc_span::FileNameDisplayPreference;
diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml
index 54641df6179..83dd6256110 100644
--- a/compiler/rustc_codegen_ssa/Cargo.toml
+++ b/compiler/rustc_codegen_ssa/Cargo.toml
@@ -33,6 +33,7 @@ rustc_incremental = { path = "../rustc_incremental" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_metadata = { path = "../rustc_metadata" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_target = { path = "../rustc_target" }
 rustc_session = { path = "../rustc_session" }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/archive.rs b/compiler/rustc_codegen_ssa/src/back/archive.rs
index 5188abdbe62..3db948a16fc 100644
--- a/compiler/rustc_codegen_ssa/src/back/archive.rs
+++ b/compiler/rustc_codegen_ssa/src/back/archive.rs
@@ -1,5 +1,5 @@
 use rustc_data_structures::temp_dir::MaybeTempDir;
-use rustc_middle::middle::cstore::DllImport;
+use rustc_session::cstore::DllImport;
 use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 43affdebbaf..ed15b464872 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -3,10 +3,10 @@ use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_errors::{ErrorReported, Handler};
 use rustc_fs_util::fix_windows_verbatim_for_gcc;
 use rustc_hir::def_id::CrateNum;
-use rustc_middle::middle::cstore::DllImport;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, LdImpl, Strip};
 use rustc_session::config::{OutputFilenames, OutputType, PrintRequest};
+use rustc_session::cstore::DllImport;
 use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
 use rustc_session::search_paths::PathKind;
 use rustc_session::utils::NativeLibKind;
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index 0fff3195808..ffeb926e648 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -8,7 +8,7 @@ use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::owning_ref::OwningRef;
 use rustc_data_structures::rustc_erase_owner;
 use rustc_data_structures::sync::MetadataRef;
-use rustc_middle::middle::cstore::MetadataLoader;
+use rustc_session::cstore::MetadataLoader;
 use rustc_target::spec::Target;
 
 use crate::METADATA_FILENAME;
diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index e842f5e9391..6e7b2968597 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -16,10 +16,10 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::definitions::{DefPathData, DefPathDataName, DisambiguatedDefPathData};
-use rustc_middle::ich::NodeIdHashingMode;
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
 use rustc_middle::ty::{self, AdtDef, ExistentialProjection, Ty, TyCtxt};
+use rustc_query_system::ich::NodeIdHashingMode;
 use rustc_target::abi::{Integer, TagEncoding, Variants};
 use smallvec::SmallVec;
 
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 70b351f6433..b759e3a7a7a 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -25,10 +25,10 @@ use rustc_data_structures::sync::Lrc;
 use rustc_hir::def_id::CrateNum;
 use rustc_hir::LangItem;
 use rustc_middle::dep_graph::WorkProduct;
-use rustc_middle::middle::cstore::{self, CrateSource};
 use rustc_middle::middle::dependency_format::Dependencies;
 use rustc_middle::ty::query::Providers;
 use rustc_session::config::{CrateType, OutputFilenames, OutputType, RUST_CGU_EXT};
+use rustc_session::cstore::{self, CrateSource};
 use rustc_session::utils::NativeLibKind;
 use rustc_span::symbol::Symbol;
 use std::path::{Path, PathBuf};
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index 50a46877c5a..8129a14fcfd 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -8,12 +8,12 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorReported;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::MetadataLoaderDyn;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_session::{
     config::{self, OutputFilenames, PrintRequest},
+    cstore::MetadataLoaderDyn,
     Session,
 };
 use rustc_span::symbol::Symbol;
diff --git a/compiler/rustc_const_eval/Cargo.toml b/compiler/rustc_const_eval/Cargo.toml
index a51273732ae..5f659dd977a 100644
--- a/compiler/rustc_const_eval/Cargo.toml
+++ b/compiler/rustc_const_eval/Cargo.toml
@@ -21,6 +21,7 @@ rustc_infer = { path = "../rustc_infer" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_mir_dataflow = { path = "../rustc_mir_dataflow" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_session = { path = "../rustc_session" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 0521443533b..cf084faade8 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -6,13 +6,13 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
 use rustc_index::vec::IndexVec;
 use rustc_macros::HashStable;
-use rustc_middle::ich::StableHashingContext;
 use rustc_middle::mir;
 use rustc_middle::ty::layout::{self, LayoutError, LayoutOf, LayoutOfHelpers, TyAndLayout};
 use rustc_middle::ty::{
     self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable,
 };
 use rustc_mir_dataflow::storage::AlwaysLiveLocals;
+use rustc_query_system::ich::StableHashingContext;
 use rustc_session::Limit;
 use rustc_span::{Pos, Span};
 use rustc_target::abi::{Align, HasDataLayout, Size, TargetDataLayout};
diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index 7fd7f6b1340..ab7ee03b643 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -25,12 +25,12 @@ use rustc_interface::util::{self, collect_crate_types, get_codegen_backend};
 use rustc_interface::{interface, Queries};
 use rustc_lint::LintStore;
 use rustc_metadata::locator;
-use rustc_middle::middle::cstore::MetadataLoader;
 use rustc_save_analysis as save;
 use rustc_save_analysis::DumpHandler;
 use rustc_serialize::json::{self, ToJson};
 use rustc_session::config::{nightly_options, CG_OPTIONS, DB_OPTIONS};
 use rustc_session::config::{ErrorOutputType, Input, OutputType, PrintRequest, TrimmedDefPaths};
+use rustc_session::cstore::MetadataLoader;
 use rustc_session::getopts;
 use rustc_session::lint::{Lint, LintId};
 use rustc_session::{config, DiagnosticOutput, Session};
diff --git a/compiler/rustc_hir/src/stable_hash_impls.rs b/compiler/rustc_hir/src/stable_hash_impls.rs
index 422a1064874..9d5ef279dd7 100644
--- a/compiler/rustc_hir/src/stable_hash_impls.rs
+++ b/compiler/rustc_hir/src/stable_hash_impls.rs
@@ -33,6 +33,25 @@ impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for HirId {
     }
 }
 
+impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for ItemLocalId {
+    type KeyType = ItemLocalId;
+
+    #[inline]
+    fn to_stable_hash_key(&self, _: &HirCtx) -> ItemLocalId {
+        *self
+    }
+}
+
+impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for BodyId {
+    type KeyType = (DefPathHash, ItemLocalId);
+
+    #[inline]
+    fn to_stable_hash_key(&self, hcx: &HirCtx) -> (DefPathHash, ItemLocalId) {
+        let BodyId { hir_id } = *self;
+        hir_id.to_stable_hash_key(hcx)
+    }
+}
+
 impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for ItemId {
     type KeyType = DefPathHash;
 
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 2d12ea94a0b..bcfa0ef3520 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -19,7 +19,6 @@ use rustc_metadata::creader::CStore;
 use rustc_metadata::{encode_metadata, EncodedMetadata};
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
-use rustc_middle::middle::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, GlobalCtxt, ResolverOutputs, TyCtxt};
 use rustc_mir_build as mir_build;
@@ -30,6 +29,7 @@ use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
 use rustc_resolve::{Resolver, ResolverArenas};
 use rustc_serialize::json;
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType, PpMode, PpSourceMode};
+use rustc_session::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_session::lint;
 use rustc_session::output::{filename_for_input, filename_for_metadata};
 use rustc_session::search_paths::PathKind;
diff --git a/compiler/rustc_macros/src/hash_stable.rs b/compiler/rustc_macros/src/hash_stable.rs
index b916113a0e5..dba885a27fe 100644
--- a/compiler/rustc_macros/src/hash_stable.rs
+++ b/compiler/rustc_macros/src/hash_stable.rs
@@ -116,14 +116,14 @@ pub fn hash_stable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::To
     s.bound_impl(
         quote!(
             ::rustc_data_structures::stable_hasher::HashStable<
-                ::rustc_middle::ich::StableHashingContext<'__ctx>,
+                ::rustc_query_system::ich::StableHashingContext<'__ctx>,
             >
         ),
         quote! {
             #[inline]
             fn hash_stable(
                 &self,
-                __hcx: &mut ::rustc_middle::ich::StableHashingContext<'__ctx>,
+                __hcx: &mut ::rustc_query_system::ich::StableHashingContext<'__ctx>,
                 __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher) {
                 #discriminant
                 match *self { #body }
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 3a05020c0b5..95b74fd5306 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -13,11 +13,11 @@ use rustc_expand::base::SyntaxExtension;
 use rustc_hir::def_id::{CrateNum, LocalDefId, StableCrateId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
 use rustc_index::vec::IndexVec;
-use rustc_middle::middle::cstore::{CrateDepKind, CrateSource, ExternCrate};
-use rustc_middle::middle::cstore::{ExternCrateSource, MetadataLoaderDyn};
 use rustc_middle::ty::TyCtxt;
 use rustc_serialize::json::ToJson;
 use rustc_session::config::{self, CrateType, ExternLocation};
+use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate};
+use rustc_session::cstore::{ExternCrateSource, MetadataLoaderDyn};
 use rustc_session::lint::{self, BuiltinLintDiagnostics, ExternDepSpec};
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
diff --git a/compiler/rustc_metadata/src/dependency_format.rs b/compiler/rustc_metadata/src/dependency_format.rs
index 6637dbd1901..ddc3e10fa48 100644
--- a/compiler/rustc_metadata/src/dependency_format.rs
+++ b/compiler/rustc_metadata/src/dependency_format.rs
@@ -55,11 +55,11 @@ use crate::creader::CStore;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::CrateNum;
-use rustc_middle::middle::cstore::CrateDepKind;
-use rustc_middle::middle::cstore::LinkagePreference::{self, RequireDynamic, RequireStatic};
 use rustc_middle::middle::dependency_format::{Dependencies, DependencyList, Linkage};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::CrateType;
+use rustc_session::cstore::CrateDepKind;
+use rustc_session::cstore::LinkagePreference::{self, RequireDynamic, RequireStatic};
 use rustc_target::spec::PanicStrategy;
 
 crate fn calculate(tcx: TyCtxt<'_>) -> Dependencies {
diff --git a/compiler/rustc_metadata/src/foreign_modules.rs b/compiler/rustc_metadata/src/foreign_modules.rs
index 9eac4c9f69b..5b42f48a7d4 100644
--- a/compiler/rustc_metadata/src/foreign_modules.rs
+++ b/compiler/rustc_metadata/src/foreign_modules.rs
@@ -1,7 +1,7 @@
 use rustc_hir as hir;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
-use rustc_middle::middle::cstore::ForeignModule;
 use rustc_middle::ty::TyCtxt;
+use rustc_session::cstore::ForeignModule;
 
 crate fn collect(tcx: TyCtxt<'_>) -> Vec<ForeignModule> {
     let mut collector = Collector { modules: Vec::new() };
diff --git a/compiler/rustc_metadata/src/locator.rs b/compiler/rustc_metadata/src/locator.rs
index 80963c9658e..abdac78ae24 100644
--- a/compiler/rustc_metadata/src/locator.rs
+++ b/compiler/rustc_metadata/src/locator.rs
@@ -221,8 +221,8 @@ use rustc_data_structures::owning_ref::OwningRef;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
 use rustc_errors::struct_span_err;
-use rustc_middle::middle::cstore::{CrateSource, MetadataLoader};
 use rustc_session::config::{self, CrateType};
+use rustc_session::cstore::{CrateSource, MetadataLoader};
 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
 use rustc_session::search_paths::PathKind;
 use rustc_session::utils::CanonicalizedPath;
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 93226b6a2f2..75b9e2ef62a 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -3,8 +3,8 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
-use rustc_middle::middle::cstore::{DllCallingConvention, DllImport, NativeLib};
 use rustc_middle::ty::{List, ParamEnv, ParamEnvAnd, Ty, TyCtxt};
+use rustc_session::cstore::{DllCallingConvention, DllImport, NativeLib};
 use rustc_session::parse::feature_err;
 use rustc_session::utils::NativeLibKind;
 use rustc_session::Session;
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index eb3a9f576a7..08fc11f21d9 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -21,8 +21,6 @@ use rustc_hir::definitions::{DefKey, DefPath, DefPathData, DefPathHash};
 use rustc_hir::lang_items;
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::hir::exports::Export;
-use rustc_middle::middle::cstore::{CrateSource, ExternCrate};
-use rustc_middle::middle::cstore::{ForeignModule, LinkagePreference, NativeLib};
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc_middle::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc_middle::mir::{self, Body, Promoted};
@@ -30,6 +28,9 @@ use rustc_middle::thir;
 use rustc_middle::ty::codec::TyDecoder;
 use rustc_middle::ty::{self, Ty, TyCtxt, Visibility};
 use rustc_serialize::{opaque, Decodable, Decoder};
+use rustc_session::cstore::{
+    CrateSource, ExternCrate, ForeignModule, LinkagePreference, NativeLib,
+};
 use rustc_session::Session;
 use rustc_span::hygiene::{ExpnIndex, MacroKind};
 use rustc_span::source_map::{respan, Spanned};
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index bd1d99640f8..292ef03d856 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -8,12 +8,11 @@ use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
 use rustc_middle::hir::exports::Export;
-use rustc_middle::middle::cstore::ForeignModule;
-use rustc_middle::middle::cstore::{CrateSource, CrateStore};
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt, Visibility};
+use rustc_session::cstore::{CrateSource, CrateStore, ForeignModule};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::{Session, StableCrateId};
 use rustc_span::hygiene::{ExpnHash, ExpnId};
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 3dc1205c4c5..072398983af 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -18,7 +18,6 @@ use rustc_hir::{AnonConst, GenericParamKind};
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_index::vec::Idx;
 use rustc_middle::hir::map::Map;
-use rustc_middle::middle::cstore::{ForeignModule, LinkagePreference, NativeLib};
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::{
     metadata_symbol_name, ExportedSymbol, SymbolExportLevel,
@@ -30,6 +29,7 @@ use rustc_middle::ty::codec::TyEncoder;
 use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_serialize::{opaque, Encodable, Encoder};
 use rustc_session::config::CrateType;
+use rustc_session::cstore::{ForeignModule, LinkagePreference, NativeLib};
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{self, ExternalSource, FileName, SourceFile, Span, SyntaxContext};
 use rustc_span::{
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index af06e1cf3f9..42855e9d9d1 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -13,13 +13,13 @@ use rustc_hir::definitions::DefKey;
 use rustc_hir::lang_items;
 use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_middle::hir::exports::Export;
-use rustc_middle::middle::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc_middle::mir;
 use rustc_middle::thir;
 use rustc_middle::ty::{self, ReprOptions, Ty};
 use rustc_serialize::opaque::Encoder;
 use rustc_session::config::SymbolManglingVersion;
+use rustc_session::cstore::{CrateDepKind, ForeignModule, LinkagePreference, NativeLib};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{ExpnIndex, MacroKind};
 use rustc_span::symbol::{Ident, Symbol};
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 2dd43a4e852..962aea448b8 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -79,8 +79,8 @@ macro_rules! arena_types {
                 >,
             [few] all_traits: Vec<rustc_hir::def_id::DefId>,
             [few] privacy_access_levels: rustc_middle::middle::privacy::AccessLevels,
-            [few] foreign_module: rustc_middle::middle::cstore::ForeignModule,
-            [few] foreign_modules: Vec<rustc_middle::middle::cstore::ForeignModule>,
+            [few] foreign_module: rustc_session::cstore::ForeignModule,
+            [few] foreign_modules: Vec<rustc_session::cstore::ForeignModule>,
             [] upvars_mentioned: rustc_data_structures::fx::FxIndexMap<rustc_hir::HirId, rustc_hir::Upvar>,
             [] object_safety_violations: rustc_middle::traits::ObjectSafetyViolation,
             [] codegen_unit: rustc_middle::mir::mono::CodegenUnit<$tcx>,
diff --git a/compiler/rustc_middle/src/dep_graph/mod.rs b/compiler/rustc_middle/src/dep_graph/mod.rs
index 35dc1631db3..70895f7b98e 100644
--- a/compiler/rustc_middle/src/dep_graph/mod.rs
+++ b/compiler/rustc_middle/src/dep_graph/mod.rs
@@ -1,7 +1,7 @@
-use crate::ich::StableHashingContext;
 use crate::ty::{self, TyCtxt};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sync::Lock;
+use rustc_query_system::ich::StableHashingContext;
 use rustc_session::Session;
 
 #[macro_use]
@@ -90,10 +90,9 @@ impl rustc_query_system::dep_graph::DepKind for DepKind {
 
 impl<'tcx> DepContext for TyCtxt<'tcx> {
     type DepKind = DepKind;
-    type StableHashingContext = StableHashingContext<'tcx>;
 
     #[inline]
-    fn create_stable_hashing_context(&self) -> Self::StableHashingContext {
+    fn create_stable_hashing_context(&self) -> StableHashingContext<'_> {
         TyCtxt::create_stable_hashing_context(*self)
     }
 
diff --git a/compiler/rustc_middle/src/hir/map/collector.rs b/compiler/rustc_middle/src/hir/map/collector.rs
index 5ecb1c9b0ff..efebf73224f 100644
--- a/compiler/rustc_middle/src/hir/map/collector.rs
+++ b/compiler/rustc_middle/src/hir/map/collector.rs
@@ -1,7 +1,6 @@
 use crate::arena::Arena;
 use crate::hir::map::Map;
 use crate::hir::{IndexedHir, OwnerNodes, ParentedNode};
-use crate::ich::StableHashingContext;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -12,6 +11,7 @@ use rustc_hir::definitions;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::*;
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_query_system::ich::StableHashingContext;
 use rustc_session::Session;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{Span, DUMMY_SP};
diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index de4b75f9463..5016c5ce954 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -6,7 +6,6 @@ pub mod exports;
 pub mod map;
 pub mod place;
 
-use crate::ich::StableHashingContext;
 use crate::ty::query::Providers;
 use crate::ty::TyCtxt;
 use rustc_ast::Attribute;
@@ -16,6 +15,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::*;
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_query_system::ich::StableHashingContext;
 use rustc_span::DUMMY_SP;
 use std::collections::BTreeMap;
 
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 594ac899f15..e41f5add457 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -81,7 +81,6 @@ pub mod arena;
 #[macro_use]
 pub mod dep_graph;
 pub mod hir;
-pub mod ich;
 pub mod infer;
 pub mod lint;
 pub mod middle;
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 37fec0ac38c..1eba2994ed3 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -1,11 +1,11 @@
 use std::cmp;
 
-use crate::ich::StableHashingContext;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::{DiagnosticBuilder, DiagnosticId};
 use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
+use rustc_query_system::ich::StableHashingContext;
 use rustc_session::lint::{
     builtin::{self, FORBIDDEN_LINT_GROUPS},
     FutureIncompatibilityReason, Level, Lint, LintId,
diff --git a/compiler/rustc_middle/src/middle/mod.rs b/compiler/rustc_middle/src/middle/mod.rs
index b370ec152e8..80a54071311 100644
--- a/compiler/rustc_middle/src/middle/mod.rs
+++ b/compiler/rustc_middle/src/middle/mod.rs
@@ -1,5 +1,4 @@
 pub mod codegen_fn_attrs;
-pub mod cstore;
 pub mod dependency_format;
 pub mod exported_symbols;
 pub mod lang_items;
diff --git a/compiler/rustc_middle/src/middle/privacy.rs b/compiler/rustc_middle/src/middle/privacy.rs
index a11ca74b25e..f33bd3438b9 100644
--- a/compiler/rustc_middle/src/middle/privacy.rs
+++ b/compiler/rustc_middle/src/middle/privacy.rs
@@ -3,7 +3,9 @@
 //! which are available for use externally when compiled as a library.
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_macros::HashStable;
+use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 use rustc_span::def_id::LocalDefId;
 use std::hash::Hash;
 
@@ -53,3 +55,12 @@ impl<Id> Default for AccessLevels<Id> {
         AccessLevels { map: Default::default() }
     }
 }
+
+impl<'a> HashStable<StableHashingContext<'a>> for AccessLevels {
+    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
+        hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
+            let AccessLevels { ref map } = *self;
+            map.hash_stable(hcx, hasher);
+        });
+    }
+}
diff --git a/compiler/rustc_middle/src/middle/region.rs b/compiler/rustc_middle/src/middle/region.rs
index e271f59da87..605e0bc2e63 100644
--- a/compiler/rustc_middle/src/middle/region.rs
+++ b/compiler/rustc_middle/src/middle/region.rs
@@ -6,10 +6,10 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/borrow_check.html
 
-use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::ty::TyCtxt;
 use rustc_hir as hir;
 use rustc_hir::Node;
+use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 2a36c01d221..971556d4463 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -803,8 +803,8 @@ pub enum ImplicitSelfKind {
 TrivialTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
 
 mod binding_form_impl {
-    use crate::ich::StableHashingContext;
     use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+    use rustc_query_system::ich::StableHashingContext;
 
     impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
         fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 776cf002c17..67a20d72905 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -1,5 +1,4 @@
 use crate::dep_graph::{DepNode, WorkProduct, WorkProductId};
-use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt};
 use rustc_attr::InlineAttr;
 use rustc_data_structures::base_n;
@@ -8,6 +7,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_hir::{HirId, ItemId};
+use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 use rustc_session::config::OptLevel;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
diff --git a/compiler/rustc_middle/src/traits/query.rs b/compiler/rustc_middle/src/traits/query.rs
index b0ab0c9ae52..cb35a4005f8 100644
--- a/compiler/rustc_middle/src/traits/query.rs
+++ b/compiler/rustc_middle/src/traits/query.rs
@@ -5,7 +5,6 @@
 //! The providers for the queries defined here can be found in
 //! `rustc_traits`.
 
-use crate::ich::StableHashingContext;
 use crate::infer::canonical::{Canonical, QueryResponse};
 use crate::ty::error::TypeError;
 use crate::ty::subst::GenericArg;
@@ -14,6 +13,7 @@ use crate::ty::{self, Ty, TyCtxt};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::struct_span_err;
+use rustc_query_system::ich::StableHashingContext;
 use rustc_span::source_map::Span;
 use std::iter::FromIterator;
 use std::mem;
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index c32f0ea9ca5..44f741c5df1 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -1,4 +1,3 @@
-use crate::ich::StableHashingContext;
 use crate::mir::interpret::ErrorHandled;
 use crate::ty;
 use crate::ty::util::{Discr, IntTypeExt};
@@ -11,6 +10,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::{self, Encodable, Encoder};
 use rustc_session::DataTypeKind;
 use rustc_span::symbol::sym;
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 01847d352c3..080e2fef203 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -3,7 +3,6 @@
 use crate::arena::Arena;
 use crate::dep_graph::DepGraph;
 use crate::hir::place::Place as HirPlace;
-use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::{struct_lint_level, LintDiagnosticBuilder, LintLevelSource};
 use crate::middle;
@@ -45,6 +44,7 @@ use rustc_hir::{
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_macros::HashStable;
 use rustc_middle::mir::FakeReadCause;
+use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{BorrowckMode, CrateType, OutputFilenames};
 use rustc_session::lint::{Level, Lint};
diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs
index 94d75a469d3..11ee942b83e 100644
--- a/compiler/rustc_middle/src/ty/fast_reject.rs
+++ b/compiler/rustc_middle/src/ty/fast_reject.rs
@@ -1,7 +1,7 @@
-use crate::ich::StableHashingContext;
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::DefId;
+use rustc_query_system::ich::StableHashingContext;
 use std::fmt::Debug;
 use std::hash::Hash;
 use std::mem;
diff --git a/compiler/rustc_middle/src/ich/impls_ty.rs b/compiler/rustc_middle/src/ty/impls_ty.rs
index 3b0640eb98d..9f47ed89f13 100644
--- a/compiler/rustc_middle/src/ich/impls_ty.rs
+++ b/compiler/rustc_middle/src/ty/impls_ty.rs
@@ -1,13 +1,13 @@
 //! This module contains `HashStable` implementations for various data types
 //! from `rustc_middle::ty` in no particular order.
 
-use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::middle::region;
 use crate::mir;
 use crate::ty;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
+use rustc_query_system::ich::StableHashingContext;
 use std::cell::RefCell;
 use std::mem;
 
@@ -163,37 +163,3 @@ impl<'a> ToStableHashKey<StableHashingContext<'a>> for region::Scope {
         *self
     }
 }
-
-impl<'a> HashStable<StableHashingContext<'a>> for ty::TyVid {
-    fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) {
-        // `TyVid` values are confined to an inference context and hence
-        // should not be hashed.
-        bug!("ty::TyKind::hash_stable() - can't hash a TyVid {:?}.", *self)
-    }
-}
-
-impl<'a> HashStable<StableHashingContext<'a>> for ty::IntVid {
-    fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) {
-        // `IntVid` values are confined to an inference context and hence
-        // should not be hashed.
-        bug!("ty::TyKind::hash_stable() - can't hash an IntVid {:?}.", *self)
-    }
-}
-
-impl<'a> HashStable<StableHashingContext<'a>> for ty::FloatVid {
-    fn hash_stable(&self, _hcx: &mut StableHashingContext<'a>, _hasher: &mut StableHasher) {
-        // `FloatVid` values are confined to an inference context and hence
-        // should not be hashed.
-        bug!("ty::TyKind::hash_stable() - can't hash a FloatVid {:?}.", *self)
-    }
-}
-
-impl<'a> HashStable<StableHashingContext<'a>> for crate::middle::privacy::AccessLevels {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
-            let crate::middle::privacy::AccessLevels { ref map } = *self;
-
-            map.hash_stable(hcx, hasher);
-        });
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index b6aeb9122c3..f13531814d6 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2,7 +2,6 @@ use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
 use crate::ty::subst::Subst;
 use crate::ty::{self, subst::SubstsRef, ReprOptions, Ty, TyCtxt, TypeFoldable};
-
 use rustc_ast as ast;
 use rustc_attr as attr;
 use rustc_hir as hir;
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 8983fda6ced..e124f0c3894 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -20,8 +20,6 @@ pub use generics::*;
 pub use vtable::*;
 
 use crate::hir::exports::ExportMap;
-use crate::ich::StableHashingContext;
-use crate::middle::cstore::CrateStoreDyn;
 use crate::mir::{Body, GeneratorLayout};
 use crate::traits::{self, Reveal};
 use crate::ty;
@@ -37,6 +35,8 @@ use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX};
 use rustc_hir::Node;
 use rustc_macros::HashStable;
+use rustc_query_system::ich::StableHashingContext;
+use rustc_session::cstore::CrateStoreDyn;
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::Span;
 use rustc_target::abi::Align;
@@ -110,6 +110,7 @@ mod context;
 mod diagnostics;
 mod erase_regions;
 mod generics;
+mod impls_ty;
 mod instance;
 mod list;
 mod structural_impls;
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index f8a476266d6..251bee0a3bf 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1,4 +1,3 @@
-use crate::middle::cstore::{ExternCrate, ExternCrateSource};
 use crate::mir::interpret::{AllocRange, ConstValue, GlobalAlloc, Pointer, Provenance, Scalar};
 use crate::ty::subst::{GenericArg, GenericArgKind, Subst};
 use crate::ty::{self, ConstInt, DefIdTree, ParamConst, ScalarInt, Ty, TyCtxt, TypeFoldable};
@@ -11,6 +10,7 @@ use rustc_hir::def_id::{DefId, DefIdSet, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefPathData, DefPathDataName, DisambiguatedDefPathData};
 use rustc_hir::ItemKind;
 use rustc_session::config::TrimmedDefPaths;
+use rustc_session::cstore::{ExternCrate, ExternCrateSource};
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi;
diff --git a/compiler/rustc_middle/src/ty/query.rs b/compiler/rustc_middle/src/ty/query.rs
index e5fd38252da..b1bc073ca99 100644
--- a/compiler/rustc_middle/src/ty/query.rs
+++ b/compiler/rustc_middle/src/ty/query.rs
@@ -3,8 +3,6 @@ use crate::hir::exports::Export;
 use crate::infer::canonical::{self, Canonical};
 use crate::lint::LintLevelMap;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
-use crate::middle::cstore::{CrateDepKind, CrateSource};
-use crate::middle::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
 use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use crate::middle::lib_features::LibFeatures;
 use crate::middle::privacy::AccessLevels;
@@ -46,6 +44,8 @@ use rustc_hir::lang_items::{LangItem, LanguageItems};
 use rustc_hir::{Crate, ItemLocalId, TraitCandidate};
 use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
+use rustc_session::cstore::{CrateDepKind, CrateSource};
+use rustc_session::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::Limits;
 use rustc_target::abi;
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index d4032cdf696..2c884813d23 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1,6 +1,5 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
-use crate::ich::NodeIdHashingMode;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::ty::fold::TypeFolder;
 use crate::ty::layout::IntegerExt;
@@ -18,6 +17,7 @@ use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
+use rustc_query_system::ich::NodeIdHashingMode;
 use rustc_span::DUMMY_SP;
 use rustc_target::abi::{Integer, Size, TargetDataLayout};
 use smallvec::SmallVec;
diff --git a/compiler/rustc_mir_transform/Cargo.toml b/compiler/rustc_mir_transform/Cargo.toml
index bde4e215a2a..e85d74ef3ea 100644
--- a/compiler/rustc_mir_transform/Cargo.toml
+++ b/compiler/rustc_mir_transform/Cargo.toml
@@ -19,6 +19,7 @@ rustc_index = { path = "../rustc_index" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_const_eval = { path = "../rustc_const_eval" }
 rustc_mir_dataflow = { path = "../rustc_mir_dataflow" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_target = { path = "../rustc_target" }
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index b9e3c058ad7..1c946bd2d8a 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -21,7 +21,6 @@ use rustc_data_structures::sync::Lrc;
 use rustc_index::vec::IndexVec;
 use rustc_middle::hir;
 use rustc_middle::hir::map::blocks::FnLikeNode;
-use rustc_middle::ich::StableHashingContext;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir::coverage::*;
 use rustc_middle::mir::dump_enabled;
@@ -30,6 +29,7 @@ use rustc_middle::mir::{
     TerminatorKind,
 };
 use rustc_middle::ty::TyCtxt;
+use rustc_query_system::ich::StableHashingContext;
 use rustc_span::def_id::DefId;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{CharPos, ExpnKind, Pos, SourceFile, Span, Symbol};
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index c14f4460a31..388c33917c6 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -10,9 +10,6 @@
 use crate::check_attr::target_from_impl_item;
 use crate::weak_lang_items;
 
-use rustc_middle::middle::cstore::ExternCrate;
-use rustc_middle::ty::TyCtxt;
-
 use rustc_ast::Attribute;
 use rustc_errors::{pluralize, struct_span_err};
 use rustc_hir as hir;
@@ -20,6 +17,8 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::lang_items::{extract, GenericRequirement, ITEM_REFS};
 use rustc_hir::{HirId, LangItem, LanguageItems, Target};
+use rustc_middle::ty::TyCtxt;
+use rustc_session::cstore::ExternCrate;
 use rustc_span::Span;
 
 use rustc_middle::ty::query::Providers;
diff --git a/compiler/rustc_plugin_impl/src/load.rs b/compiler/rustc_plugin_impl/src/load.rs
index 51cf85f794b..c21075a443c 100644
--- a/compiler/rustc_plugin_impl/src/load.rs
+++ b/compiler/rustc_plugin_impl/src/load.rs
@@ -4,7 +4,7 @@ use crate::Registry;
 use rustc_ast::Crate;
 use rustc_errors::struct_span_err;
 use rustc_metadata::locator;
-use rustc_middle::middle::cstore::MetadataLoader;
+use rustc_session::cstore::MetadataLoader;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index bb0e6511159..e50a8c191ad 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -20,10 +20,10 @@ use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::DiagnosticBuilder;
 use rustc_middle::dep_graph;
-use rustc_middle::ich::StableHashingContext;
 use rustc_middle::ty::query::{query_keys, query_storage, query_stored, query_values};
 use rustc_middle::ty::query::{Providers, QueryEngine};
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_query_system::ich::StableHashingContext;
 use rustc_span::Span;
 
 #[macro_use]
diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index 818b798ab55..b71a1722036 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -36,7 +36,6 @@ impl<'tcx> std::ops::Deref for QueryCtxt<'tcx> {
 
 impl HasDepContext for QueryCtxt<'tcx> {
     type DepKind = rustc_middle::dep_graph::DepKind;
-    type StableHashingContext = rustc_middle::ich::StableHashingContext<'tcx>;
     type DepContext = TyCtxt<'tcx>;
 
     #[inline]
diff --git a/compiler/rustc_query_system/Cargo.toml b/compiler/rustc_query_system/Cargo.toml
index 11c18a497e5..898a8caa3ca 100644
--- a/compiler/rustc_query_system/Cargo.toml
+++ b/compiler/rustc_query_system/Cargo.toml
@@ -10,12 +10,16 @@ doctest = false
 rustc_arena = { path = "../rustc_arena" }
 tracing = "0.1"
 rustc-rayon-core = "0.3.1"
+rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
-rustc_macros = { path = "../rustc_macros" }
+rustc_feature = { path = "../rustc_feature" }
+rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
+rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
+rustc_target = { path = "../rustc_target" }
 parking_lot = "0.11"
 smallvec = { version = "1.6.1", features = ["union", "may_dangle"] }
diff --git a/compiler/rustc_query_system/src/dep_graph/dep_node.rs b/compiler/rustc_query_system/src/dep_graph/dep_node.rs
index 46dc0c720ce..dd500015374 100644
--- a/compiler/rustc_query_system/src/dep_graph/dep_node.rs
+++ b/compiler/rustc_query_system/src/dep_graph/dep_node.rs
@@ -43,10 +43,10 @@
 //!   lost during fingerprint computation.
 
 use super::{DepContext, DepKind};
+use crate::ich::StableHashingContext;
 
 use rustc_data_structures::fingerprint::{Fingerprint, PackedFingerprint};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-
 use std::fmt;
 use std::hash::Hash;
 
@@ -119,7 +119,7 @@ pub trait DepNodeParams<Ctxt: DepContext>: fmt::Debug + Sized {
 
 impl<Ctxt: DepContext, T> DepNodeParams<Ctxt> for T
 where
-    T: HashStable<Ctxt::StableHashingContext> + fmt::Debug,
+    T: for<'a> HashStable<StableHashingContext<'a>> + fmt::Debug,
 {
     #[inline]
     default fn can_reconstruct_query_key() -> bool {
diff --git a/compiler/rustc_query_system/src/dep_graph/graph.rs b/compiler/rustc_query_system/src/dep_graph/graph.rs
index 23a43771842..114d12fb90b 100644
--- a/compiler/rustc_query_system/src/dep_graph/graph.rs
+++ b/compiler/rustc_query_system/src/dep_graph/graph.rs
@@ -1,3 +1,4 @@
+use parking_lot::Mutex;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::profiling::{EventId, QueryInvocationId, SelfProfilerRef};
@@ -7,8 +8,6 @@ use rustc_data_structures::steal::Steal;
 use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock, Lrc, Ordering};
 use rustc_index::vec::IndexVec;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
-
-use parking_lot::Mutex;
 use smallvec::{smallvec, SmallVec};
 use std::collections::hash_map::Entry;
 use std::fmt::Debug;
@@ -19,6 +18,7 @@ use std::sync::atomic::Ordering::Relaxed;
 use super::query::DepGraphQuery;
 use super::serialized::{GraphEncoder, SerializedDepGraph, SerializedDepNodeIndex};
 use super::{DepContext, DepKind, DepNode, HasDepContext, WorkProductId};
+use crate::ich::StableHashingContext;
 use crate::query::{QueryContext, QuerySideEffects};
 
 #[cfg(debug_assertions)]
@@ -96,9 +96,9 @@ struct DepGraphData<K: DepKind> {
     dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
 }
 
-pub fn hash_result<HashCtxt, R>(hcx: &mut HashCtxt, result: &R) -> Option<Fingerprint>
+pub fn hash_result<R>(hcx: &mut StableHashingContext<'_>, result: &R) -> Option<Fingerprint>
 where
-    R: HashStable<HashCtxt>,
+    R: for<'a> HashStable<StableHashingContext<'a>>,
 {
     let mut stable_hasher = StableHasher::new();
     result.hash_stable(hcx, &mut stable_hasher);
@@ -215,7 +215,7 @@ impl<K: DepKind> DepGraph<K> {
         cx: Ctxt,
         arg: A,
         task: fn(Ctxt, A) -> R,
-        hash_result: fn(&mut Ctxt::StableHashingContext, &R) -> Option<Fingerprint>,
+        hash_result: fn(&mut StableHashingContext<'_>, &R) -> Option<Fingerprint>,
     ) -> (R, DepNodeIndex) {
         if self.is_fully_enabled() {
             self.with_task_impl(key, cx, arg, task, hash_result)
@@ -234,7 +234,7 @@ impl<K: DepKind> DepGraph<K> {
         cx: Ctxt,
         arg: A,
         task: fn(Ctxt, A) -> R,
-        hash_result: fn(&mut Ctxt::StableHashingContext, &R) -> Option<Fingerprint>,
+        hash_result: fn(&mut StableHashingContext<'_>, &R) -> Option<Fingerprint>,
     ) -> (R, DepNodeIndex) {
         // This function is only called when the graph is enabled.
         let data = self.data.as_ref().unwrap();
diff --git a/compiler/rustc_query_system/src/dep_graph/mod.rs b/compiler/rustc_query_system/src/dep_graph/mod.rs
index b5be1192ce7..2afef210254 100644
--- a/compiler/rustc_query_system/src/dep_graph/mod.rs
+++ b/compiler/rustc_query_system/src/dep_graph/mod.rs
@@ -9,6 +9,7 @@ pub use graph::{hash_result, DepGraph, DepNodeColor, DepNodeIndex, TaskDeps, Wor
 pub use query::DepGraphQuery;
 pub use serialized::{SerializedDepGraph, SerializedDepNodeIndex};
 
+use crate::ich::StableHashingContext;
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sync::Lock;
 use rustc_serialize::{opaque::FileEncoder, Encodable};
@@ -19,10 +20,9 @@ use std::hash::Hash;
 
 pub trait DepContext: Copy {
     type DepKind: self::DepKind;
-    type StableHashingContext;
 
     /// Create a hashing context for hashing new results.
-    fn create_stable_hashing_context(&self) -> Self::StableHashingContext;
+    fn create_stable_hashing_context(&self) -> StableHashingContext<'_>;
 
     /// Access the DepGraph.
     fn dep_graph(&self) -> &DepGraph<Self::DepKind>;
@@ -36,18 +36,13 @@ pub trait DepContext: Copy {
 
 pub trait HasDepContext: Copy {
     type DepKind: self::DepKind;
-    type StableHashingContext;
-    type DepContext: self::DepContext<
-        DepKind = Self::DepKind,
-        StableHashingContext = Self::StableHashingContext,
-    >;
+    type DepContext: self::DepContext<DepKind = Self::DepKind>;
 
     fn dep_context(&self) -> &Self::DepContext;
 }
 
 impl<T: DepContext> HasDepContext for T {
     type DepKind = T::DepKind;
-    type StableHashingContext = T::StableHashingContext;
     type DepContext = Self;
 
     fn dep_context(&self) -> &Self::DepContext {
diff --git a/compiler/rustc_middle/src/ich/hcx.rs b/compiler/rustc_query_system/src/ich/hcx.rs
index 4b4f65a062f..f2e935c59fc 100644
--- a/compiler/rustc_middle/src/ich/hcx.rs
+++ b/compiler/rustc_query_system/src/ich/hcx.rs
@@ -1,7 +1,4 @@
 use crate::ich;
-use crate::middle::cstore::CrateStore;
-use crate::ty::TyCtxt;
-
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -9,6 +6,7 @@ use rustc_data_structures::sync::Lrc;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::definitions::{DefPathHash, Definitions};
+use rustc_session::cstore::CrateStore;
 use rustc_session::Session;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::Symbol;
@@ -179,42 +177,15 @@ impl<'a> StableHashingContext<'a> {
     }
 }
 
-/// Something that can provide a stable hashing context.
-pub trait StableHashingContextProvider<'a> {
-    fn get_stable_hashing_context(&self) -> StableHashingContext<'a>;
-}
-
-impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b T {
-    fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
-        (**self).get_stable_hashing_context()
-    }
-}
-
-impl<'a, 'b, T: StableHashingContextProvider<'a>> StableHashingContextProvider<'a> for &'b mut T {
-    fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
-        (**self).get_stable_hashing_context()
-    }
-}
-
-impl StableHashingContextProvider<'tcx> for TyCtxt<'tcx> {
-    fn get_stable_hashing_context(&self) -> StableHashingContext<'tcx> {
-        (*self).create_stable_hashing_context()
-    }
-}
-
-impl<'a> StableHashingContextProvider<'a> for StableHashingContext<'a> {
-    fn get_stable_hashing_context(&self) -> StableHashingContext<'a> {
-        self.clone()
-    }
-}
-
 impl<'a> HashStable<StableHashingContext<'a>> for ast::NodeId {
+    #[inline]
     fn hash_stable(&self, _: &mut StableHashingContext<'a>, _: &mut StableHasher) {
         panic!("Node IDs should not appear in incremental state");
     }
 }
 
 impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
+    #[inline]
     fn hash_spans(&self) -> bool {
         self.hash_spans
     }
@@ -229,6 +200,7 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
         self.definitions.def_span(def_id)
     }
 
+    #[inline]
     fn span_data_to_lines_and_cols(
         &mut self,
         span: &SpanData,
@@ -237,4 +209,4 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
     }
 }
 
-impl rustc_session::HashStableContext for StableHashingContext<'a> {}
+impl<'a> rustc_session::HashStableContext for StableHashingContext<'a> {}
diff --git a/compiler/rustc_middle/src/ich/impls_hir.rs b/compiler/rustc_query_system/src/ich/impls_hir.rs
index 5dfd00bc6d4..04eb263a977 100644
--- a/compiler/rustc_middle/src/ich/impls_hir.rs
+++ b/compiler/rustc_query_system/src/ich/impls_hir.rs
@@ -2,7 +2,6 @@
 //! types in no particular order.
 
 use crate::ich::{NodeIdHashingMode, StableHashingContext};
-use rustc_attr as attr;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_hir as hir;
@@ -27,6 +26,7 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         }
     }
 
+    #[inline]
     fn hash_body_id(&mut self, id: hir::BodyId, hasher: &mut StableHasher) {
         let hcx = self;
         if hcx.hash_bodies() {
@@ -34,6 +34,7 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         }
     }
 
+    #[inline]
     fn hash_reference_to_item(&mut self, id: hir::HirId, hasher: &mut StableHasher) {
         let hcx = self;
 
@@ -42,6 +43,7 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         })
     }
 
+    #[inline]
     fn hash_hir_mod(&mut self, module: &hir::Mod<'_>, hasher: &mut StableHasher) {
         let hcx = self;
         let hir::Mod { inner: ref inner_span, ref item_ids } = *module;
@@ -104,6 +106,7 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         }
     }
 
+    #[inline]
     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;
@@ -114,16 +117,8 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
     }
 }
 
-impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::ItemLocalId {
-    type KeyType = hir::ItemLocalId;
-
-    #[inline]
-    fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> hir::ItemLocalId {
-        *self
-    }
-}
-
 impl<'a> HashStable<StableHashingContext<'a>> for hir::Body<'_> {
+    #[inline]
     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
         let hir::Body { params, value, generator_kind } = self;
 
@@ -135,19 +130,6 @@ impl<'a> HashStable<StableHashingContext<'a>> for hir::Body<'_> {
     }
 }
 
-impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::BodyId {
-    type KeyType = (DefPathHash, hir::ItemLocalId);
-
-    #[inline]
-    fn to_stable_hash_key(
-        &self,
-        hcx: &StableHashingContext<'a>,
-    ) -> (DefPathHash, hir::ItemLocalId) {
-        let hir::BodyId { hir_id } = *self;
-        hir_id.to_stable_hash_key(hcx)
-    }
-}
-
 impl<'a> HashStable<StableHashingContext<'a>> for hir::TraitCandidate {
     fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
         hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
@@ -171,21 +153,3 @@ impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::TraitCandidate {
         )
     }
 }
-
-impl<'hir> HashStable<StableHashingContext<'hir>> for attr::InlineAttr {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-    }
-}
-
-impl<'hir> HashStable<StableHashingContext<'hir>> for attr::InstructionSetAttr {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-    }
-}
-
-impl<'hir> HashStable<StableHashingContext<'hir>> for attr::OptimizeAttr {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'hir>, hasher: &mut StableHasher) {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-    }
-}
diff --git a/compiler/rustc_middle/src/ich/impls_syntax.rs b/compiler/rustc_query_system/src/ich/impls_syntax.rs
index acf2990b643..acf2990b643 100644
--- a/compiler/rustc_middle/src/ich/impls_syntax.rs
+++ b/compiler/rustc_query_system/src/ich/impls_syntax.rs
diff --git a/compiler/rustc_middle/src/ich/mod.rs b/compiler/rustc_query_system/src/ich/mod.rs
index e8e5c4a2669..54416902e5f 100644
--- a/compiler/rustc_middle/src/ich/mod.rs
+++ b/compiler/rustc_query_system/src/ich/mod.rs
@@ -1,13 +1,11 @@
 //! ICH - Incremental Compilation Hash
 
-pub use self::hcx::{NodeIdHashingMode, StableHashingContext, StableHashingContextProvider};
+pub use self::hcx::{NodeIdHashingMode, StableHashingContext};
 use rustc_span::symbol::{sym, Symbol};
 
 mod hcx;
-
 mod impls_hir;
 mod impls_syntax;
-mod impls_ty;
 
 pub const IGNORED_ATTRIBUTES: &[Symbol] = &[
     sym::cfg,
diff --git a/compiler/rustc_query_system/src/lib.rs b/compiler/rustc_query_system/src/lib.rs
index c205f0fb531..bc23de069b0 100644
--- a/compiler/rustc_query_system/src/lib.rs
+++ b/compiler/rustc_query_system/src/lib.rs
@@ -1,3 +1,4 @@
+#![feature(assert_matches)]
 #![feature(bool_to_option)]
 #![feature(core_intrinsics)]
 #![feature(hash_raw_entry)]
@@ -14,4 +15,5 @@ extern crate rustc_macros;
 
 pub mod cache;
 pub mod dep_graph;
+pub mod ich;
 pub mod query;
diff --git a/compiler/rustc_query_system/src/query/config.rs b/compiler/rustc_query_system/src/query/config.rs
index d1e527dff98..76a165ed8e6 100644
--- a/compiler/rustc_query_system/src/query/config.rs
+++ b/compiler/rustc_query_system/src/query/config.rs
@@ -2,6 +2,7 @@
 
 use crate::dep_graph::DepNode;
 use crate::dep_graph::SerializedDepNodeIndex;
+use crate::ich::StableHashingContext;
 use crate::query::caches::QueryCache;
 use crate::query::{QueryCacheStore, QueryContext, QueryState};
 
@@ -23,7 +24,7 @@ pub(crate) struct QueryVtable<CTX: QueryContext, K, V> {
     pub dep_kind: CTX::DepKind,
     pub eval_always: bool,
 
-    pub hash_result: fn(&mut CTX::StableHashingContext, &V) -> Option<Fingerprint>,
+    pub hash_result: fn(&mut StableHashingContext<'_>, &V) -> Option<Fingerprint>,
     pub handle_cycle_error: fn(CTX, DiagnosticBuilder<'_>) -> V,
     pub cache_on_disk: fn(CTX, &K, Option<&V>) -> bool,
     pub try_load_from_disk: fn(CTX, SerializedDepNodeIndex) -> Option<V>,
@@ -39,7 +40,7 @@ impl<CTX: QueryContext, K, V> QueryVtable<CTX, K, V> {
 
     pub(crate) fn hash_result(
         &self,
-        hcx: &mut CTX::StableHashingContext,
+        hcx: &mut StableHashingContext<'_>,
         value: &V,
     ) -> Option<Fingerprint> {
         (self.hash_result)(hcx, value)
@@ -74,10 +75,8 @@ pub trait QueryAccessors<CTX: QueryContext>: QueryConfig {
     // Don't use this method to compute query results, instead use the methods on TyCtxt
     fn compute_fn(tcx: CTX, key: &Self::Key) -> fn(CTX::DepContext, Self::Key) -> Self::Value;
 
-    fn hash_result(
-        hcx: &mut CTX::StableHashingContext,
-        result: &Self::Value,
-    ) -> Option<Fingerprint>;
+    fn hash_result(hcx: &mut StableHashingContext<'_>, result: &Self::Value)
+    -> Option<Fingerprint>;
 
     fn handle_cycle_error(tcx: CTX, diag: DiagnosticBuilder<'_>) -> Self::Value;
 }
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 8dfa839453d..2a562a06cb3 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -27,8 +27,8 @@ use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_INDEX};
 use rustc_metadata::creader::LoadedMacro;
 use rustc_middle::bug;
 use rustc_middle::hir::exports::Export;
-use rustc_middle::middle::cstore::CrateStore;
 use rustc_middle::ty;
+use rustc_session::cstore::CrateStore;
 use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind};
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 04a1fae8fb7..3e7783033ef 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -51,10 +51,10 @@ use rustc_hir::TraitCandidate;
 use rustc_index::vec::IndexVec;
 use rustc_metadata::creader::{CStore, CrateLoader};
 use rustc_middle::hir::exports::ExportMap;
-use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn};
 use rustc_middle::span_bug;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, DefIdTree, MainDefinition, ResolverOutputs};
+use rustc_session::cstore::{CrateStore, MetadataLoaderDyn};
 use rustc_session::lint;
 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::Session;
diff --git a/compiler/rustc_save_analysis/src/lib.rs b/compiler/rustc_save_analysis/src/lib.rs
index d69d7daa555..543cd0247a5 100644
--- a/compiler/rustc_save_analysis/src/lib.rs
+++ b/compiler/rustc_save_analysis/src/lib.rs
@@ -19,11 +19,11 @@ use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::Node;
 use rustc_hir_pretty::{enum_def_to_string, fn_to_string, ty_to_string};
 use rustc_middle::hir::map::Map;
-use rustc_middle::middle::cstore::ExternCrate;
 use rustc_middle::middle::privacy::AccessLevels;
 use rustc_middle::ty::{self, print::with_no_trimmed_paths, DefIdTree, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::config::{CrateType, Input, OutputType};
+use rustc_session::cstore::ExternCrate;
 use rustc_session::output::{filename_for_metadata, out_filename};
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::Ident;
diff --git a/compiler/rustc_session/Cargo.toml b/compiler/rustc_session/Cargo.toml
index 4cff21bee3d..37cfc4a0dc3 100644
--- a/compiler/rustc_session/Cargo.toml
+++ b/compiler/rustc_session/Cargo.toml
@@ -9,6 +9,7 @@ rustc_macros = { path = "../rustc_macros" }
 tracing = "0.1"
 rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
+rustc_hir = { path = "../rustc_hir" }
 rustc_target = { path = "../rustc_target" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_data_structures = { path = "../rustc_data_structures" }
diff --git a/compiler/rustc_middle/src/middle/cstore.rs b/compiler/rustc_session/src/cstore.rs
index 2a1bb43a466..9d6bd201039 100644
--- a/compiler/rustc_middle/src/middle/cstore.rs
+++ b/compiler/rustc_session/src/cstore.rs
@@ -2,13 +2,12 @@
 //! are *mostly* used as a part of that interface, but these should
 //! probably get a better home if someone can find one.
 
+use crate::search_paths::PathKind;
+use crate::utils::NativeLibKind;
 use rustc_ast as ast;
 use rustc_data_structures::sync::{self, MetadataRef};
 use rustc_hir::def_id::{CrateNum, DefId, StableCrateId, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
-use rustc_macros::HashStable;
-use rustc_session::search_paths::PathKind;
-use rustc_session::utils::NativeLibKind;
 use rustc_span::hygiene::{ExpnHash, ExpnId};
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
@@ -21,7 +20,7 @@ use std::path::{Path, PathBuf};
 
 /// Where a crate came from on the local filesystem. One of these three options
 /// must be non-None.
-#[derive(PartialEq, Clone, Debug, HashStable, Encodable, Decodable)]
+#[derive(PartialEq, Clone, Debug, HashStable_Generic, Encodable, Decodable)]
 pub struct CrateSource {
     pub dylib: Option<(PathBuf, PathKind)>,
     pub rlib: Option<(PathBuf, PathKind)>,
@@ -29,13 +28,14 @@ pub struct CrateSource {
 }
 
 impl CrateSource {
+    #[inline]
     pub fn paths(&self) -> impl Iterator<Item = &PathBuf> {
         self.dylib.iter().chain(self.rlib.iter()).chain(self.rmeta.iter()).map(|p| &p.0)
     }
 }
 
 #[derive(Encodable, Decodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
-#[derive(HashStable)]
+#[derive(HashStable_Generic)]
 pub enum CrateDepKind {
     /// A dependency that is only used for its macros.
     MacrosOnly,
@@ -48,6 +48,7 @@ pub enum CrateDepKind {
 }
 
 impl CrateDepKind {
+    #[inline]
     pub fn macros_only(self) -> bool {
         match self {
             CrateDepKind::MacrosOnly => true,
@@ -56,13 +57,13 @@ impl CrateDepKind {
     }
 }
 
-#[derive(Copy, Debug, PartialEq, Clone, Encodable, Decodable, HashStable)]
+#[derive(Copy, Debug, PartialEq, Clone, Encodable, Decodable, HashStable_Generic)]
 pub enum LinkagePreference {
     RequireDynamic,
     RequireStatic,
 }
 
-#[derive(Debug, Encodable, Decodable, HashStable)]
+#[derive(Debug, Encodable, Decodable, HashStable_Generic)]
 pub struct NativeLib {
     pub kind: NativeLibKind,
     pub name: Option<Symbol>,
@@ -73,7 +74,7 @@ pub struct NativeLib {
     pub dll_imports: Vec<DllImport>,
 }
 
-#[derive(Clone, Debug, Encodable, Decodable, HashStable)]
+#[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
 pub struct DllImport {
     pub name: Symbol,
     pub ordinal: Option<u16>,
@@ -90,7 +91,7 @@ pub struct DllImport {
 ///
 /// The usize value, where present, indicates the size of the function's argument list
 /// in bytes.
-#[derive(Clone, PartialEq, Debug, Encodable, Decodable, HashStable)]
+#[derive(Clone, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
 pub enum DllCallingConvention {
     C,
     Stdcall(usize),
@@ -98,13 +99,13 @@ pub enum DllCallingConvention {
     Vectorcall(usize),
 }
 
-#[derive(Clone, TyEncodable, TyDecodable, HashStable, Debug)]
+#[derive(Clone, Encodable, Decodable, HashStable_Generic, Debug)]
 pub struct ForeignModule {
     pub foreign_items: Vec<DefId>,
     pub def_id: DefId,
 }
 
-#[derive(Copy, Clone, Debug, HashStable)]
+#[derive(Copy, Clone, Debug, HashStable_Generic)]
 pub struct ExternCrate {
     pub src: ExternCrateSource,
 
@@ -123,10 +124,12 @@ impl ExternCrate {
     /// If true, then this crate is the crate named by the extern
     /// crate referenced above. If false, then this crate is a dep
     /// of the crate.
+    #[inline]
     pub fn is_direct(&self) -> bool {
         self.dependency_of == LOCAL_CRATE
     }
 
+    #[inline]
     pub fn rank(&self) -> impl PartialOrd {
         // Prefer:
         // - direct extern crate to indirect
@@ -135,7 +138,7 @@ impl ExternCrate {
     }
 }
 
-#[derive(Copy, Clone, Debug, HashStable)]
+#[derive(Copy, Clone, Debug, HashStable_Generic)]
 pub enum ExternCrateSource {
     /// Crate is loaded by `extern crate`.
     Extern(
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 9a82ae3fc10..6c86f86ecd9 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -1,4 +1,5 @@
 #![feature(crate_visibility_modifier)]
+#![feature(min_specialization)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
 
@@ -14,6 +15,7 @@ pub mod parse;
 mod code_stats;
 #[macro_use]
 pub mod config;
+pub mod cstore;
 pub mod filesearch;
 mod options;
 pub mod search_paths;
@@ -28,4 +30,4 @@ pub use getopts;
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
 /// instead of implementing everything in `rustc_middle`.
-pub trait HashStableContext {}
+pub trait HashStableContext: rustc_ast::HashStableContext + rustc_hir::HashStableContext {}
diff --git a/compiler/rustc_symbol_mangling/Cargo.toml b/compiler/rustc_symbol_mangling/Cargo.toml
index d5befa10e23..b9751f0adb5 100644
--- a/compiler/rustc_symbol_mangling/Cargo.toml
+++ b/compiler/rustc_symbol_mangling/Cargo.toml
@@ -16,4 +16,5 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_target = { path = "../rustc_target" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_session = { path = "../rustc_session" }
diff --git a/compiler/rustc_symbol_mangling/src/legacy.rs b/compiler/rustc_symbol_mangling/src/legacy.rs
index e236ef996bc..de18614360e 100644
--- a/compiler/rustc_symbol_mangling/src/legacy.rs
+++ b/compiler/rustc_symbol_mangling/src/legacy.rs
@@ -1,12 +1,12 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::CrateNum;
 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
-use rustc_middle::ich::NodeIdHashingMode;
 use rustc_middle::mir::interpret::{ConstValue, Scalar};
 use rustc_middle::ty::print::{PrettyPrinter, Print, Printer};
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::util::common::record_time;
+use rustc_query_system::ich::NodeIdHashingMode;
 
 use tracing::debug;
 
diff --git a/compiler/rustc_trait_selection/Cargo.toml b/compiler/rustc_trait_selection/Cargo.toml
index 9a9737362c6..aa1074709a0 100644
--- a/compiler/rustc_trait_selection/Cargo.toml
+++ b/compiler/rustc_trait_selection/Cargo.toml
@@ -18,6 +18,7 @@ rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_infer = { path = "../rustc_infer" }
 rustc_macros = { path = "../rustc_macros" }
+rustc_query_system = { path = "../rustc_query_system" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }