2 files changed, 37 insertions, 0 deletions
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index e33e26b5165..b264be15edf 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1646,6 +1646,21 @@ void VarDecl::setStorageClass(StorageClass SC) {
   VarDeclBits.SClass = SC;
 }
 
+VarDecl::TLSKind VarDecl::getTLSKind() const {
+  switch (VarDeclBits.TSCSpec) {
+  case TSCS_unspecified:
+    if (hasAttr<ThreadAttr>())
+      return TLS_Static;
+    return TLS_None;
+  case TSCS___thread: // Fall through.
+  case TSCS__Thread_local:
+      return TLS_Static;
+  case TSCS_thread_local:
+    return TLS_Dynamic;
+  }
+  llvm_unreachable("Unknown thread storage class specifier!");
+}
+
 SourceRange VarDecl::getSourceRange() const {
   if (const Expr *Init = getInit()) {
     SourceLocation InitEnd = Init->getLocEnd();
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 1920182ce20..c33408f193a 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3697,6 +3697,25 @@ static void handleMSInheritanceAttr(Sema &S, Decl *D, const AttributeList &Attr)
     D->addAttr(IA);
 }
 
+static void handleDeclspecThreadAttr(Sema &S, Decl *D,
+                                     const AttributeList &Attr) {
+  VarDecl *VD = cast<VarDecl>(D);
+  if (!S.Context.getTargetInfo().isTLSSupported()) {
+    S.Diag(Attr.getLoc(), diag::err_thread_unsupported);
+    return;
+  }
+  if (VD->getTSCSpec() != TSCS_unspecified) {
+    S.Diag(Attr.getLoc(), diag::err_declspec_thread_on_thread_variable);
+    return;
+  }
+  if (VD->hasLocalStorage()) {
+    S.Diag(Attr.getLoc(), diag::err_thread_non_global) << "__declspec(thread)";
+    return;
+  }
+  VD->addAttr(::new (S.Context) ThreadAttr(
+      Attr.getRange(), S.Context, Attr.getAttributeSpellingListIndex()));
+}
+
 static void handleARMInterruptAttr(Sema &S, Decl *D,
                                    const AttributeList &Attr) {
   // Check the attribute arguments.
@@ -4394,6 +4413,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_SelectAny:
     handleSimpleAttribute<SelectAnyAttr>(S, D, Attr);
     break;
+  case AttributeList::AT_Thread:
+    handleDeclspecThreadAttr(S, D, Attr);
+    break;
 
   // Thread safety attributes:
   case AttributeList::AT_AssertExclusiveLock: