From ef9403371f2d4759cd7b0d0a276e63aae2ce68fe Mon Sep 17 00:00:00 2001 From: John Kåre Alsaker Date: Sat, 2 Mar 2024 18:32:42 +0100 Subject: Drop AST on a separate thread and prefetch `hir_crate` --- compiler/rustc_ast_lowering/src/lib.rs | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'compiler/rustc_ast_lowering/src') diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index 1e14b4d6723..8b1c63cd21d 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -49,6 +49,7 @@ use rustc_attr_parsing::{AttributeParser, OmitDoc}; use rustc_data_structures::fingerprint::Fingerprint; use rustc_data_structures::sorted_map::SortedMap; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; +use rustc_data_structures::sync::spawn; use rustc_data_structures::tagged_ptr::TaggedRef; use rustc_errors::{DiagArgFromDisplay, DiagCtxtHandle, StashKey}; use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res}; @@ -454,9 +455,14 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> { .lower_node(def_id); } - // Drop AST to free memory drop(ast_index); - sess.time("drop_ast", || drop(krate)); + + // Drop AST to free memory. It can be expensive so try to drop it on a separate thread. + let prof = sess.prof.clone(); + spawn(move || { + let _timer = prof.verbose_generic_activity("drop_ast"); + drop(krate); + }); // Don't hash unless necessary, because it's expensive. let opt_hir_hash = -- cgit 1.4.1-3-g733a5