Make THIR building a stealable query

compiler/rustc_mir_build/src/build/block.rs

@@ -1,8 +1,8 @@
 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

@@ -1,8 +1,8 @@
 //! 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 rustc_index::vec::Idx;
 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

@@ -1,8 +1,8 @@
 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

@@ -1,7 +1,6 @@
 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::thir::*;
 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_data_structures::fx::FxHashMap;
 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};