From 5a7ce4609e3a7c364d9ff8810329242cefb76a4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Fri, 3 Feb 2023 09:04:12 +0100
Subject: [PATCH] Support TLS access into dylibs on Windows

---
 src/constant.rs | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/constant.rs b/src/constant.rs
index 31278f810..ebb4de33f 100644
--- a/src/constant.rs
+++ b/src/constant.rs
@@ -54,12 +54,22 @@ pub(crate) fn codegen_tls_ref<'tcx>(
     def_id: DefId,
     layout: TyAndLayout<'tcx>,
 ) -> CValue<'tcx> {
-    let data_id = data_id_for_static(fx.tcx, fx.module, def_id, false);
-    let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
-    if fx.clif_comments.enabled() {
-        fx.add_comment(local_data_id, format!("tls {:?}", def_id));
-    }
-    let tls_ptr = fx.bcx.ins().tls_value(fx.pointer_type, local_data_id);
+    let tls_ptr = if !def_id.is_local() && fx.tcx.needs_thread_local_shim(def_id) {
+        let instance = ty::Instance {
+            def: ty::InstanceDef::ThreadLocalShim(def_id),
+            substs: ty::InternalSubsts::empty(),
+        };
+        let func_ref = fx.get_function_ref(instance);
+        let call = fx.bcx.ins().call(func_ref, &[]);
+        fx.bcx.func.dfg.first_result(call)
+    } else {
+        let data_id = data_id_for_static(fx.tcx, fx.module, def_id, false);
+        let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+        if fx.clif_comments.enabled() {
+            fx.add_comment(local_data_id, format!("tls {:?}", def_id));
+        }
+        fx.bcx.ins().tls_value(fx.pointer_type, local_data_id)
+    };
     CValue::by_val(tls_ptr, layout)
 }