[Cygwin] Use -femulated-tls by default since r257718 introduced the new pass.

FIXME: Add more targets to use emutls into clang/test/Driver/emulated-tls.cpp.
FIXME: Add cygwin tests into llvm/test/CodeGen/X86. Working in progress.
llvm-svn: 257984

4 files changed, 9 insertions, 6 deletions

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5a25e0b0632..ea3dcf28357 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -74,6 +74,8 @@ Windows Support
 
 Clang's support for building native Windows programs ...
 
+TLS is enabled for Cygwin defaults to -femulated-tls.
+
 
 C Language Changes in Clang
 ---------------------------
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 90c25726df2..080fef8d9e9 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -4597,7 +4597,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddLastArg(CmdArgs, options::OPT_fno_operator_names);
   // Emulated TLS is enabled by default on Android, and can be enabled manually
   // with -femulated-tls.
-  bool EmulatedTLSDefault = Triple.isAndroid();
+  bool EmulatedTLSDefault = Triple.isAndroid() || Triple.isWindowsCygwinEnvironment();
   if (Args.hasFlag(options::OPT_femulated_tls, options::OPT_fno_emulated_tls,
                    EmulatedTLSDefault))
     CmdArgs.push_back("-femulated-tls");
diff --git a/clang/test/Driver/emulated-tls.cpp b/clang/test/Driver/emulated-tls.cpp
new file mode 100644
index 00000000000..a18c2e220bf
--- /dev/null
+++ b/clang/test/Driver/emulated-tls.cpp
@@ -0,0 +1,5 @@
+// Cygwin uses emutls. Clang should pass -femulated-tls to cc1 and cc1 should pass EmulatedTLS to LLVM CodeGen.
+// FIXME: Add more targets here to use emutls.
+// RUN: %clang -### -std=c++11 -target i686-pc-cygwin %s 2>&1 | FileCheck %s
+
+// CHECK: "-cc1" {{.*}}"-femulated-tls"
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 6904714ec78..4d0cccefca7 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -12477,17 +12477,13 @@ X86TargetLowering::LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const {
 
   GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
 
-  // Cygwin uses emutls.
-  // FIXME: It may be EmulatedTLS-generic also for X86-Android.
-  if (Subtarget->isTargetWindowsCygwin())
+  if (DAG.getTarget().Options.EmulatedTLS)
     return LowerToTLSEmulatedModel(GA, DAG);
 
   const GlobalValue *GV = GA->getGlobal();
   auto PtrVT = getPointerTy(DAG.getDataLayout());
 
   if (Subtarget->isTargetELF()) {
-    if (DAG.getTarget().Options.EmulatedTLS)
-      return LowerToTLSEmulatedModel(GA, DAG);
     TLSModel::Model model = DAG.getTarget().getTLSModel(GV);
     switch (model) {
       case TLSModel::GeneralDynamic: