TLS: Respect visibility for thread_local variables on Darwin (PR40327)

Summary:
Teach clang to mark thread wrappers for thread_local variables with
hidden visibility when the original variable is marked with hidden
visibility. This is necessary on Darwin which exposes the thread wrapper
instead of the thread variable. The thread wrapper would previously
always be created with default visibility unless it had
linkonce*/weak_odr linkage.

Reviewers: rjmccall

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D56818

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@351457 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index b53304528c3d82228e090ed8ecc8b31345fe4bc1..c56875a0368099bd59c6c0620e31b025054cc2cc 100644 (file)
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -2463,10 +2463,12 @@ ItaniumCXXABI::getOrCreateThreadLocalWrapper(const VarDecl *VD,
     CGM.SetLLVMFunctionAttributesForDefinition(nullptr, Wrapper);
 
   // Always resolve references to the wrapper at link time.
-  if (!Wrapper->hasLocalLinkage() && !(isThreadWrapperReplaceable(VD, CGM) &&
-      !llvm::GlobalVariable::isLinkOnceLinkage(Wrapper->getLinkage()) &&
-      !llvm::GlobalVariable::isWeakODRLinkage(Wrapper->getLinkage())))
-    Wrapper->setVisibility(llvm::GlobalValue::HiddenVisibility);
+  if (!Wrapper->hasLocalLinkage())
+    if (!isThreadWrapperReplaceable(VD, CGM) ||
+        llvm::GlobalVariable::isLinkOnceLinkage(Wrapper->getLinkage()) ||
+        llvm::GlobalVariable::isWeakODRLinkage(Wrapper->getLinkage()) ||
+        VD->getVisibility() == HiddenVisibility)
+      Wrapper->setVisibility(llvm::GlobalValue::HiddenVisibility);
 
   if (isThreadWrapperReplaceable(VD, CGM)) {
     Wrapper->setCallingConv(llvm::CallingConv::CXX_FAST_TLS);

diff --git a/test/CodeGenCXX/cxx11-thread-local-visibility.cpp b/test/CodeGenCXX/cxx11-thread-local-visibility.cpp
new file mode 100644 (file)
index 0000000..b46d41d
--- /dev/null
+++ b/test/CodeGenCXX/cxx11-thread-local-visibility.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck --check-prefix=LINUX %s
+// RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple x86_64-apple-darwin12 | FileCheck --check-prefix=DARWIN %s
+
+// Regression test for PR40327
+
+// LINUX: @default_tls = thread_local global i32
+// LINUX: @hidden_tls = hidden thread_local global i32
+// LINUX: define weak_odr hidden i32* @_ZTW11default_tls()
+// LINUX: define weak_odr hidden i32* @_ZTW10hidden_tls()
+//
+// DARWIN: @default_tls = internal thread_local global i32
+// DARWIN: @hidden_tls = internal thread_local global i32
+// DARWIN: define cxx_fast_tlscc i32* @_ZTW11default_tls()
+// DARWIN: define hidden cxx_fast_tlscc i32* @_ZTW10hidden_tls()
+
+__attribute__((visibility("default"))) thread_local int default_tls;
+__attribute__((visibility("hidden"))) thread_local int hidden_tls;

diff --git a/test/CodeGenCXX/cxx11-thread-local.cpp b/test/CodeGenCXX/cxx11-thread-local.cpp
index 156c4f591908b1b5858536adcf29a2825cc93e2c..de941af1afb87ae8bce6263cdd3b5724dea62fc0 100644 (file)
--- a/test/CodeGenCXX/cxx11-thread-local.cpp
+++ b/test/CodeGenCXX/cxx11-thread-local.cpp
@@ -318,7 +318,7 @@ void set_anon_i() {
 // CHECK-NOT: call void @[[V_M_INIT]]()
 
 
-// LIUNX: define weak_odr hidden i32* @_ZTW1a() {
+// LINUX: define weak_odr hidden i32* @_ZTW1a()
 // DARWIN: define cxx_fast_tlscc i32* @_ZTW1a()
 // LINUX:   call void @_ZTH1a()
 // DARWIN: call cxx_fast_tlscc void @_ZTH1a()