From 03af82bb0cc425ff7d4518f36a80a5cb26b6a821 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Sat, 11 Jan 2020 04:02:22 +0100
Subject: [PATCH] Prefetch exported symbols

---
 src/librustc_metadata/rmeta/encoder.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/librustc_metadata/rmeta/encoder.rs b/src/librustc_metadata/rmeta/encoder.rs
index 74824e1f91be..4fb116b551d9 100644
--- a/src/librustc_metadata/rmeta/encoder.rs
+++ b/src/librustc_metadata/rmeta/encoder.rs
@@ -1726,10 +1726,15 @@ pub(super) fn encode_metadata(tcx: TyCtxt<'_>) -> EncodedMetadata {
         || {
             // Prefetch some queries used by metadata encoding
             tcx.dep_graph.with_ignore(|| {
-                par_for_each_in(tcx.mir_keys(LOCAL_CRATE), |&def_id| {
-                    tcx.optimized_mir(def_id);
-                    tcx.promoted_mir(def_id);
-                });
+                join(
+                    || {
+                        par_for_each_in(tcx.mir_keys(LOCAL_CRATE), |&def_id| {
+                            tcx.optimized_mir(def_id);
+                            tcx.promoted_mir(def_id);
+                        })
+                    },
+                    || tcx.exported_symbols(LOCAL_CRATE),
+                );
             })
         },
     )