Don't use thread local shims for foreign thread locals

Author: Zoxc

Diff for: compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -188,7 +188,7 @@ fn exported_symbols_provider_local(
     // Export TLS shims
     if !tcx.sess.target.dll_tls_export {
         symbols.extend(sorted.iter().filter_map(|(&def_id, &info)| {
-            tcx.is_thread_local_static(def_id).then(|| {
+            tcx.needs_thread_local_shim(def_id).then(|| {
                 (
                     ExportedSymbol::ThreadLocalShim(def_id),
                     SymbolExportInfo {

Diff for: compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -463,7 +463,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             mir::Rvalue::ThreadLocalRef(def_id) => {
                 assert!(bx.cx().tcx().is_static(def_id));
                 let layout = bx.layout_of(bx.cx().tcx().static_ptr_ty(def_id));
-                let static_ = if !def_id.is_local() && !bx.cx().tcx().sess.target.dll_tls_export {
+                let static_ = if !def_id.is_local() && bx.cx().tcx().needs_thread_local_shim(def_id)
+                {
                     let instance = ty::Instance {
                         def: ty::InstanceDef::ThreadLocalShim(def_id),
                         substs: ty::InternalSubsts::empty(),

Diff for: compiler/rustc_middle/src/ty/util.rs

@@ -599,6 +599,15 @@ impl<'tcx> TyCtxt<'tcx> {
         self.static_mutability(def_id) == Some(hir::Mutability::Mut)
     }
 
+    /// Returns `true` if the item pointed to by `def_id` is a thread local which needs a
+    /// thread local shim generated.
+    #[inline]
+    pub fn needs_thread_local_shim(self, def_id: DefId) -> bool {
+        !self.sess.target.dll_tls_export
+            && self.is_thread_local_static(def_id)
+            && !self.is_foreign_item(def_id)
+    }
+
     /// Returns the type a reference to the thread local takes in MIR.
     pub fn thread_local_ptr_ty(self, def_id: DefId) -> Ty<'tcx> {
         let static_ty = self.type_of(def_id).subst_identity();

Diff for: compiler/rustc_monomorphize/src/collector.rs

@@ -464,7 +464,7 @@ fn collect_items_rec<'tcx>(
                 }
             }
 
-            if !tcx.sess.target.dll_tls_export && tcx.is_thread_local_static(def_id) {
+            if tcx.needs_thread_local_shim(def_id) {
                 neighbors.push(respan(
                     starting_point.span,
                     MonoItem::Fn(Instance {