Extend the IL for selecting TLS models (PR9788)
This allows the user/front-end to specify a model that is better
than what LLVM would choose by default. For example, a variable
might be declared as
@x = thread_local(initialexec) global i32 42
if it will not be used in a shared library that is dlopen'ed.
If the specified model isn't supported by the target, or if LLVM can
make a better choice, a different model may be used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159077 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CppBackend/CPPBackend.cpp b/lib/Target/CppBackend/CPPBackend.cpp
index cd2ebcb..0ea2a29 100644
--- a/lib/Target/CppBackend/CPPBackend.cpp
+++ b/lib/Target/CppBackend/CPPBackend.cpp
@@ -130,6 +130,7 @@
private:
void printLinkageType(GlobalValue::LinkageTypes LT);
void printVisibilityType(GlobalValue::VisibilityTypes VisTypes);
+ void printThreadLocalMode(GlobalVariable::ThreadLocalMode TLM);
void printCallingConv(CallingConv::ID cc);
void printEscapedString(const std::string& str);
void printCFP(const ConstantFP* CFP);
@@ -325,6 +326,26 @@
}
}
+void CppWriter::printThreadLocalMode(GlobalVariable::ThreadLocalMode TLM) {
+ switch (TLM) {
+ case GlobalVariable::NotThreadLocal:
+ Out << "GlobalVariable::NotThreadLocal";
+ break;
+ case GlobalVariable::GeneralDynamicTLSModel:
+ Out << "GlobalVariable::GeneralDynamicTLSModel";
+ break;
+ case GlobalVariable::LocalDynamicTLSModel:
+ Out << "GlobalVariable::LocalDynamicTLSModel";
+ break;
+ case GlobalVariable::InitialExecTLSModel:
+ Out << "GlobalVariable::InitialExecTLSModel";
+ break;
+ case GlobalVariable::LocalExecTLSModel:
+ Out << "GlobalVariable::LocalExecTLSModel";
+ break;
+ }
+}
+
// printEscapedString - Print each character of the specified string, escaping
// it if it is not printable or if it is an escape char.
void CppWriter::printEscapedString(const std::string &Str) {
@@ -996,7 +1017,9 @@
}
if (GV->isThreadLocal()) {
printCppName(GV);
- Out << "->setThreadLocal(true);";
+ Out << "->setThreadLocalMode(";
+ printThreadLocalMode(GV->getThreadLocalMode());
+ Out << ");";
nl(Out);
}
if (is_inline) {
diff --git a/lib/Target/TargetMachine.cpp b/lib/Target/TargetMachine.cpp
index 6cdab5a..3825719 100644
--- a/lib/Target/TargetMachine.cpp
+++ b/lib/Target/TargetMachine.cpp
@@ -77,6 +77,24 @@
return CodeGenInfo->getCodeModel();
}
+/// Get the IR-specified TLS model for Var.
+static TLSModel::Model getSelectedTLSModel(const GlobalVariable *Var) {
+ switch (Var->getThreadLocalMode()) {
+ case GlobalVariable::NotThreadLocal:
+ llvm_unreachable("getSelectedTLSModel for non-TLS variable");
+ break;
+ case GlobalVariable::GeneralDynamicTLSModel:
+ return TLSModel::GeneralDynamic;
+ case GlobalVariable::LocalDynamicTLSModel:
+ return TLSModel::LocalDynamic;
+ case GlobalVariable::InitialExecTLSModel:
+ return TLSModel::InitialExec;
+ case GlobalVariable::LocalExecTLSModel:
+ return TLSModel::LocalExec;
+ }
+ llvm_unreachable("invalid TLS model");
+}
+
TLSModel::Model TargetMachine::getTLSModel(const GlobalValue *GV) const {
// If GV is an alias then use the aliasee for determining
// thread-localness.
@@ -86,22 +104,31 @@
bool isLocal = Var->hasLocalLinkage();
bool isDeclaration = Var->isDeclaration();
+ bool isPIC = getRelocationModel() == Reloc::PIC_;
+ bool isPIE = Options.PositionIndependentExecutable;
// FIXME: what should we do for protected and internal visibility?
// For variables, is internal different from hidden?
bool isHidden = Var->hasHiddenVisibility();
- if (getRelocationModel() == Reloc::PIC_ &&
- !Options.PositionIndependentExecutable) {
+ TLSModel::Model Model;
+ if (isPIC && !isPIE) {
if (isLocal || isHidden)
- return TLSModel::LocalDynamic;
+ Model = TLSModel::LocalDynamic;
else
- return TLSModel::GeneralDynamic;
+ Model = TLSModel::GeneralDynamic;
} else {
if (!isDeclaration || isHidden)
- return TLSModel::LocalExec;
+ Model = TLSModel::LocalExec;
else
- return TLSModel::InitialExec;
+ Model = TLSModel::InitialExec;
}
+
+ // If the user specified a more specific model, use that.
+ TLSModel::Model SelectedModel = getSelectedTLSModel(Var);
+ if (SelectedModel > Model)
+ return SelectedModel;
+
+ return Model;
}
/// getOptLevel - Returns the optimization level: None, Less,
@@ -135,4 +162,3 @@
void TargetMachine::setDataSections(bool V) {
DataSections = V;
}
-