From f22390ac3f273defcf6988b9ab3c805ced85323c Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Tue, 31 Oct 2017 11:41:57 -0400
Subject: [PATCH] short-circuit some iterations in `jl_recache_type` to speed
 up loading of large precompiled packages. (#24407)

extracted from #24399

(cherry picked from commit b8d42d43d3d5bc3c1cf999dd8c24481c8b1594f4)
---
 src/dump.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/dump.c b/src/dump.c
index 0b9d3e228da5e7..c49bc2168e79f1 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -3035,6 +3035,8 @@ static jl_datatype_t *jl_recache_type(jl_datatype_t *dt, size_t start, jl_value_
         t = dt;
     }
     assert(t->uid != 0);
+    if (t == dt && v == NULL)
+        return t;
     // delete / replace any other usages of this type in the backref list
     // with the newly constructed object
     size_t i = start;
@@ -3087,8 +3089,7 @@ static void jl_recache_types(void)
             if (jl_is_datatype(o)) {
                 dt = (jl_datatype_t*)o;
                 v = dt->instance;
-                assert(dt->uid == -1);
-                t = jl_recache_type(dt, i + 2, NULL);
+                t = dt->uid == -1 ? jl_recache_type(dt, i + 2, NULL) : dt;
             }
             else {
                 dt = (jl_datatype_t*)jl_typeof(o);