Make liveness checking more parallel

Author: Zoxc

src/librustc_interface/passes.rs

@@ -810,6 +810,19 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
 
     sess.time("misc_checking_2", || {
         parallel!(
+            {
+                sess.time("liveness_checking", || {
+                    par_for_each(&tcx.hir().krate().modules, |(&module, _)| {
+                        // this must run before MIR dump, because
+                        // "not all control paths return a value" is reported here.
+                        //
+                        // maybe move the check to a MIR pass?
+                        let local_def_id = tcx.hir().local_def_id(module);
+
+                        tcx.ensure().check_mod_liveness(local_def_id);
+                    });
+                });
+            },
             {
                 sess.time("match_checking", || {
                     tcx.par_body_owners(|def_id| {
@@ -818,15 +831,9 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
                 });
             },
             {
-                sess.time("liveness_and_intrinsic_checking", || {
+                sess.time("intrinsic_checking", || {
                     par_for_each(&tcx.hir().krate().modules, |(&module, _)| {
-                        // this must run before MIR dump, because
-                        // "not all control paths return a value" is reported here.
-                        //
-                        // maybe move the check to a MIR pass?
                         let local_def_id = tcx.hir().local_def_id(module);
-
-                        tcx.ensure().check_mod_liveness(local_def_id);
                         tcx.ensure().check_mod_intrinsics(local_def_id);
                     });
                 });

src/librustc_passes/liveness.rs

@@ -106,6 +106,7 @@ use rustc_hir as hir;
 use rustc_hir::def::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, FnKind, NestedVisitorMap, Visitor};
+use rustc_hir::itemlikevisit::ParItemLikeVisitor;
 use rustc_hir::{Expr, HirId, HirIdMap, HirIdSet, Node};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
@@ -182,11 +183,28 @@ impl<'tcx> Visitor<'tcx> for IrMaps<'tcx> {
     }
 }
 
+struct LivenessVisitor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    module_def_id: DefId,
+}
+
+impl<'tcx> ParItemLikeVisitor<'tcx> for LivenessVisitor<'tcx> {
+    fn visit_item(&self, item: &'tcx hir::Item<'tcx>) {
+        IrMaps::new(self.tcx, self.module_def_id).visit_item(item);
+    }
+
+    fn visit_trait_item(&self, trait_item: &'tcx hir::TraitItem<'tcx>) {
+        IrMaps::new(self.tcx, self.module_def_id).visit_trait_item(trait_item);
+    }
+
+    fn visit_impl_item(&self, impl_item: &'tcx hir::ImplItem<'tcx>) {
+        IrMaps::new(self.tcx, self.module_def_id).visit_impl_item(impl_item);
+    }
+}
+
 fn check_mod_liveness(tcx: TyCtxt<'_>, module_def_id: DefId) {
-    tcx.hir().visit_item_likes_in_module(
-        module_def_id,
-        &mut IrMaps::new(tcx, module_def_id).as_deep_visitor(),
-    );
+    tcx.hir()
+        .par_visit_item_likes_in_module(module_def_id, &LivenessVisitor { tcx, module_def_id });
 }
 
 pub fn provide(providers: &mut Providers<'_>) {

src/test/ui/lint/lint-uppercase-variables.stderr

@@ -1,47 +1,47 @@
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+warning: unused variable: `Foo`
   --> $DIR/lint-uppercase-variables.rs:22:9
    |
 LL |         Foo => {}
-   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
+   |         ^^^ help: consider prefixing with an underscore: `_Foo`
    |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
+note: the lint level is defined here
+  --> $DIR/lint-uppercase-variables.rs:1:9
+   |
+LL | #![warn(unused)]
+   |         ^^^^^^
+   = note: `#[warn(unused_variables)]` implied by `#[warn(unused)]`
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+warning: unused variable: `Foo`
   --> $DIR/lint-uppercase-variables.rs:28:9
    |
 LL |     let Foo = foo::Foo::Foo;
-   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
+   |         ^^^ help: consider prefixing with an underscore: `_Foo`
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+warning: unused variable: `Foo`
   --> $DIR/lint-uppercase-variables.rs:33:17
    |
 LL |     fn in_param(Foo: foo::Foo) {}
-   |                 ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
+   |                 ^^^ help: consider prefixing with an underscore: `_Foo`
 
-warning: unused variable: `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:22:9
    |
 LL |         Foo => {}
-   |         ^^^ help: consider prefixing with an underscore: `_Foo`
-   |
-note: the lint level is defined here
-  --> $DIR/lint-uppercase-variables.rs:1:9
+   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
    |
-LL | #![warn(unused)]
-   |         ^^^^^^
-   = note: `#[warn(unused_variables)]` implied by `#[warn(unused)]`
+   = note: `#[warn(bindings_with_variant_name)]` on by default
 
-warning: unused variable: `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:28:9
    |
 LL |     let Foo = foo::Foo::Foo;
-   |         ^^^ help: consider prefixing with an underscore: `_Foo`
+   |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
 
-warning: unused variable: `Foo`
+warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:33:17
    |
 LL |     fn in_param(Foo: foo::Foo) {}
-   |                 ^^^ help: consider prefixing with an underscore: `_Foo`
+   |                 ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
 
 error: structure field `X` should have a snake case name
   --> $DIR/lint-uppercase-variables.rs:10:5