Make THIR building a stealable query

compiler/rustc_middle/src/arena.rs

@@ -14,6 +14,7 @@
             [] layouts: rustc_target::abi::Layout,
             // AdtDef are interned and compared by address
             [] adt_def: rustc_middle::ty::AdtDef,
+            [] steal_thir: rustc_data_structures::steal::Steal<rustc_middle::thir::Thir<$tcx>>,
             [] steal_mir: rustc_data_structures::steal::Steal<rustc_middle::mir::Body<$tcx>>,
             [decode] mir: rustc_middle::mir::Body<$tcx>,
             [] steal_promoted:

compiler/rustc_middle/src/dep_graph/dep_node.rs

@@ -285,7 +285,7 @@ pub mod label_strs {
 // required that their size stay the same, but we don't want to change
 // it inadvertently. This assert just ensures we're aware of any change.
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-static_assert_size!(DepNode, 17);
+static_assert_size!(DepNode, 18);
 
 #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
 static_assert_size!(DepNode, 24);

compiler/rustc_middle/src/query/mod.rs

@@ -220,6 +220,11 @@
         desc { "checking if the crate is_panic_runtime" }
     }
 
+    /// Fetch the THIR for a given body.
+    query thir_body(key: ty::WithOptConstParam<LocalDefId>) -> (&'tcx Steal<thir::Thir<'tcx>>, thir::ExprId) {
+        desc { |tcx| "building THIR for `{}`", tcx.def_path_str(key.did.to_def_id()) }
+    }
+
     /// Set of all the `DefId`s in this crate that have MIR associated with
     /// them. This includes all the body owners, but also things like struct
     /// constructors.

compiler/rustc_middle/src/thir.rs

@@ -24,18 +24,21 @@
 use std::ops::Index;
 
 newtype_index! {
+    #[derive(HashStable)]
     pub struct ArmId {
         DEBUG_FORMAT = "a{}"
     }
 }
 
 newtype_index! {
+    #[derive(HashStable)]
     pub struct ExprId {
         DEBUG_FORMAT = "e{}"
     }
 }
 
 newtype_index! {
+    #[derive(HashStable)]
     pub struct StmtId {
         DEBUG_FORMAT = "s{}"
     }
@@ -43,6 +46,7 @@ pub struct StmtId {
 
 macro_rules! thir_with_elements {
     ($($name:ident: $id:ty => $value:ty,)*) => {
+        #[derive(Debug, HashStable)]
         pub struct Thir<'tcx> {
             $(
                 pub $name: IndexVec<$id, $value>,
@@ -76,13 +80,13 @@ fn index(&self, index: $id) -> &Self::Output {
     stmts: StmtId => Stmt<'tcx>,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, HashStable)]
 pub enum LintLevel {
     Inherited,
     Explicit(hir::HirId),
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct Block {
     pub targeted_by_break: bool,
     pub region_scope: region::Scope,
@@ -93,7 +97,7 @@ pub struct Block {
     pub safety_mode: BlockSafety,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, HashStable)]
 pub enum BlockSafety {
     Safe,
     ExplicitUnsafe(hir::HirId),
@@ -101,13 +105,13 @@ pub enum BlockSafety {
     PopUnsafe,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct Stmt<'tcx> {
     pub kind: StmtKind<'tcx>,
     pub opt_destruction_scope: Option<region::Scope>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub enum StmtKind<'tcx> {
     Expr {
         /// scope for this statement; may be used as lifetime of temporaries
@@ -157,7 +161,7 @@ pub enum StmtKind<'tcx> {
 /// MIR simplifications are already done in the impl of `Thir`. For
 /// example, method calls and overloaded operators are absent: they are
 /// expected to be converted into `Expr::Call` instances.
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct Expr<'tcx> {
     /// type of this expression
     pub ty: Ty<'tcx>,
@@ -173,7 +177,7 @@ pub struct Expr<'tcx> {
     pub kind: ExprKind<'tcx>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub enum ExprKind<'tcx> {
     Scope {
         region_scope: region::Scope,
@@ -363,19 +367,19 @@ pub enum ExprKind<'tcx> {
     },
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct FieldExpr {
     pub name: Field,
     pub expr: ExprId,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct FruInfo<'tcx> {
     pub base: ExprId,
     pub field_types: Box<[Ty<'tcx>]>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub struct Arm<'tcx> {
     pub pattern: Pat<'tcx>,
     pub guard: Option<Guard<'tcx>>,
@@ -385,19 +389,19 @@ pub struct Arm<'tcx> {
     pub span: Span,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub enum Guard<'tcx> {
     If(ExprId),
     IfLet(Pat<'tcx>, ExprId),
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, HashStable)]
 pub enum LogicalOp {
     And,
     Or,
 }
 
-#[derive(Debug)]
+#[derive(Debug, HashStable)]
 pub enum InlineAsmOperand<'tcx> {
     In {
         reg: InlineAsmRegOrRegClass,
@@ -431,19 +435,19 @@ pub enum InlineAsmOperand<'tcx> {
     },
 }
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub enum BindingMode {
     ByValue,
     ByRef(BorrowKind),
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, HashStable)]
 pub struct FieldPat<'tcx> {
     pub field: Field,
     pub pattern: Pat<'tcx>,
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, HashStable)]
 pub struct Pat<'tcx> {
     pub ty: Ty<'tcx>,
     pub span: Span,
@@ -456,7 +460,7 @@ pub fn wildcard_from_ty(ty: Ty<'tcx>) -> Self {
     }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub struct PatTyProj<'tcx> {
     pub user_ty: CanonicalUserType<'tcx>,
 }
@@ -483,7 +487,7 @@ pub fn user_ty(
     }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub struct Ascription<'tcx> {
     pub user_ty: PatTyProj<'tcx>,
     /// Variance to use when relating the type `user_ty` to the **type of the value being
@@ -508,7 +512,7 @@ pub struct Ascription<'tcx> {
     pub user_ty_span: Span,
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, HashStable)]
 pub enum PatKind<'tcx> {
     Wild,
 
@@ -586,7 +590,7 @@ pub enum PatKind<'tcx> {
     },
 }
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub struct PatRange<'tcx> {
     pub lo: &'tcx ty::Const<'tcx>,
     pub hi: &'tcx ty::Const<'tcx>,

compiler/rustc_middle/src/ty/context.rs

@@ -13,6 +13,7 @@
 use crate::middle::stability;
 use crate::mir::interpret::{self, Allocation, ConstValue, Scalar};
 use crate::mir::{Body, Field, Local, Place, PlaceElem, ProjectionKind, Promoted};
+use crate::thir::Thir;
 use crate::traits;
 use crate::ty::query::{self, OnDiskCache, TyCtxtAt};
 use crate::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSubsts};
@@ -1041,6 +1042,10 @@ pub fn typeck_opt_const_arg(
         }
     }
 
+    pub fn alloc_steal_thir(self, thir: Thir<'tcx>) -> &'tcx Steal<Thir<'tcx>> {
+        self.arena.alloc(Steal::new(thir))
+    }
+
     pub fn alloc_steal_mir(self, mir: Body<'tcx>) -> &'tcx Steal<Body<'tcx>> {
         self.arena.alloc(Steal::new(mir))
     }

compiler/rustc_middle/src/ty/query/mod.rs

@@ -18,6 +18,7 @@
 use crate::mir::interpret::{ConstAlloc, LitToConstError, LitToConstInput};
 use crate::mir::interpret::{ConstValue, EvalToAllocationRawResult, EvalToConstValueResult};
 use crate::mir::mono::CodegenUnit;
+use crate::thir;
 use crate::traits::query::{
     CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal,
     CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal,

compiler/rustc_middle/src/ty/sty.rs

@@ -669,7 +669,7 @@ pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, HashStable)]
 pub enum UpvarSubsts<'tcx> {
     Closure(SubstsRef<'tcx>),
     Generator(SubstsRef<'tcx>),

compiler/rustc_mir_build/src/build/block.rs

 use crate::build::matches::ArmHasGuard;
 use crate::build::ForGuard::OutsideGuard;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
-use rustc_middle::thir::*;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 use rustc_session::lint::builtin::UNSAFE_OP_IN_UNSAFE_FN;
 use rustc_session::lint::Level;
 use rustc_span::Span;

compiler/rustc_mir_build/src/build/expr/as_constant.rs

 //! See docs in build/expr/mod.rs
 
 use crate::build::Builder;
-use rustc_middle::thir::*;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 use rustc_middle::ty::CanonicalUserTypeAnnotation;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {

compiler/rustc_mir_build/src/build/expr/as_operand.rs

@@ -2,9 +2,9 @@
 
 use crate::build::expr::category::Category;
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
-use rustc_middle::thir::*;
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Returns an operand suitable for use until the end of the current

compiler/rustc_mir_build/src/build/expr/as_place.rs

@@ -3,13 +3,13 @@
 use crate::build::expr::category::Category;
 use crate::build::ForGuard::{OutsideGuard, RefWithinGuard};
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
-use rustc_middle::thir::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::HirId;
 use rustc_middle::hir::place::ProjectionKind as HirProjectionKind;
 use rustc_middle::middle::region;
 use rustc_middle::mir::AssertKind::BoundsCheck;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 use rustc_middle::ty::AdtDef;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt, Variance};
 use rustc_span::Span;

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -5,11 +5,11 @@
 use crate::build::expr::as_place::PlaceBase;
 use crate::build::expr::category::{Category, RvalueFunc};
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
-use rustc_middle::thir::*;
 use rustc_middle::middle::region;
 use rustc_middle::mir::AssertKind;
 use rustc_middle::mir::Place;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 use rustc_middle::ty::{self, Ty, UpvarSubsts};
 use rustc_span::Span;
 

compiler/rustc_mir_build/src/build/expr/as_temp.rs

@@ -2,10 +2,10 @@
 
 use crate::build::scope::DropKind;
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
-use rustc_middle::thir::*;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr` into a fresh temporary. This is used when building

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -2,13 +2,13 @@
 
 use crate::build::expr::category::{Category, RvalueFunc};
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
-use rustc_middle::thir::*;
 use rustc_ast::InlineAsmOptions;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_index::vec::Idx;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation};
 use std::iter;
 

compiler/rustc_mir_build/src/build/expr/stmt.rs

 use crate::build::scope::BreakableTarget;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
-use rustc_middle::thir::*;
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
+use rustc_middle::thir::*;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Builds a block of MIR statements to evaluate the THIR `expr`.

compiler/rustc_mir_build/src/build/mod.rs

 use crate::build;
 use crate::build::expr::as_place::PlaceBuilder;
 use crate::build::scope::DropKind;
-use crate::thir::build_thir;
 use crate::thir::pattern::pat_from_hir;
 use rustc_attr::{self as attr, UnwindAttr};
 use rustc_errors::ErrorReported;
@@ -106,7 +105,8 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
             };
 
             let body = tcx.hir().body(body_id);
-            let (thir, expr) = build_thir(tcx, def, &body.value);
+            let (thir, expr) = tcx.thir_body(def);
+            let thir = thir.steal();
             let ty = tcx.type_of(fn_def_id);
             let mut abi = fn_sig.abi;
             let implicit_argument = match ty.kind() {
@@ -214,8 +214,8 @@ fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_
 
             let return_ty = typeck_results.node_type(id);
 
-            let ast_expr = &tcx.hir().body(body_id).value;
-            let (thir, expr) = build_thir(tcx, def, ast_expr);
+            let (thir, expr) = tcx.thir_body(def);
+            let thir = thir.steal();
 
             build::construct_const(&thir, &infcx, expr, def, id, return_ty, return_ty_span)
         };

compiler/rustc_mir_build/src/lib.rs

@@ -31,4 +31,5 @@ pub fn provide(providers: &mut Providers) {
     providers.mir_built = build::mir_built;
     providers.thir_check_unsafety = check_unsafety::thir_check_unsafety;
     providers.thir_check_unsafety_for_const_arg = check_unsafety::thir_check_unsafety_for_const_arg;
+    providers.thir_body = thir::cx::thir_body;
 }

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -2,10 +2,11 @@
 //! structures into the THIR. The `builder` is generally ignorant of the tcx,
 //! etc., and instead goes through the `Cx` for most of its work.
 
-use crate::thir::util::UserAnnotatedTyHelpers;
 use crate::thir::pattern::pat_from_hir;
+use crate::thir::util::UserAnnotatedTyHelpers;
 
 use rustc_ast as ast;
+use rustc_data_structures::steal::Steal;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::Node;
@@ -15,14 +16,15 @@
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 
-pub fn build_thir<'tcx>(
+crate fn thir_body<'tcx>(
     tcx: TyCtxt<'tcx>,
     owner_def: ty::WithOptConstParam<LocalDefId>,
-    expr: &'tcx hir::Expr<'tcx>,
-) -> (Thir<'tcx>, ExprId) {
+) -> (&'tcx Steal<Thir<'tcx>>, ExprId) {
+    let hir = tcx.hir();
+    let body = hir.body(hir.body_owned_by(hir.local_def_id_to_hir_id(owner_def.did)));
     let mut cx = Cx::new(tcx, owner_def);
-    let expr = cx.mirror_expr(expr);
-    (cx.thir, expr)
+    let expr = cx.mirror_expr(&body.value);
+    (tcx.alloc_steal_thir(cx.thir), expr)
 }
 
 struct Cx<'tcx> {

compiler/rustc_mir_build/src/thir/mod.rs

@@ -7,7 +7,6 @@
 crate mod constant;
 
 crate mod cx;
-pub use cx::build_thir;
 
 crate mod pattern;
 

compiler/rustc_mir_build/src/thir/pattern/usefulness.rs

@@ -292,8 +292,8 @@
 use rustc_arena::TypedArena;
 use rustc_hir::def_id::DefId;
 use rustc_hir::HirId;
-use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::thir::{Pat, PatKind};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 
 use smallvec::{smallvec, SmallVec};