Emit the TLS intialization functions into a list.

Add the TLS initialization functions to a list of initialization functions. The
back-end takes this list and places the function pointers into the correct
section. This way they're called before `main().'

<rdar://problem/13733006>

llvm-svn: 180739

1 files changed, 26 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index bf67bd1007a..6247b15ce98 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -182,6 +182,7 @@ void CodeGenModule::Release() {
       AddGlobalCtor(ObjCInitFunction);
   EmitCtorList(GlobalCtors, "llvm.global_ctors");
   EmitCtorList(GlobalDtors, "llvm.global_dtors");
+  EmitTLSList(TLSInitFuncs);
   EmitGlobalAnnotations();
   EmitStaticExternCAliases();
   EmitLLVMUsed();
@@ -479,6 +480,12 @@ void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
   GlobalDtors.push_back(std::make_pair(Dtor, Priority));
 }
 
+/// AddTLSInitFunc - Add a function to the list that will initialize TLS
+/// variables before main() runs.
+void CodeGenModule::AddTLSInitFunc(llvm::Function *Init) {
+  TLSInitFuncs.push_back(Init);
+}
+
 void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
   // Ctor function type is void()*.
   llvm::FunctionType* CtorFTy = llvm::FunctionType::get(VoidTy, false);
@@ -507,6 +514,25 @@ void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
   }
 }
 
+void CodeGenModule::EmitTLSList(ArrayRef<llvm::Constant*> Fns) {
+  if (Fns.empty()) return;
+
+  // TLS init function types are void()*.
+  llvm::FunctionType* TLSFTy = llvm::FunctionType::get(VoidTy, false);
+  llvm::Type *TLSPFTy = llvm::PointerType::getUnqual(TLSFTy);
+
+  SmallVector<llvm::Constant*, 8> Inits;
+  for (ArrayRef<llvm::Constant*>::iterator I = Fns.begin(),
+         E = Fns.end(); I != E; ++I)
+    Inits.push_back(llvm::ConstantExpr::getBitCast(*I, TLSPFTy));
+
+  llvm::ArrayType *AT = llvm::ArrayType::get(TLSPFTy, Inits.size());
+  new llvm::GlobalVariable(TheModule, AT, false,
+                           llvm::GlobalValue::AppendingLinkage,
+                           llvm::ConstantArray::get(AT, Inits),
+                           "llvm.tls_init_funcs");
+}
+
 llvm::GlobalValue::LinkageTypes
 CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
   GVALinkage Linkage = getContext().GetGVALinkageForFunction(D);