Windows: Return current thread’s _Init_thread_epoch from __emutls_get…

…_address. Fixes function level static variables.

interpreter/cling/lib/Interpreter/Interpreter.cpp

@@ -61,6 +61,8 @@
 
 using namespace clang;
 
+extern "C" void* __emutls_get_address(struct __emutls_control*);
+
 namespace {
 
   // Forward cxa_atexit for global d'tors.
@@ -267,6 +269,16 @@ namespace cling {
           }
         }
       }
+#ifdef LLVM_ON_WIN32
+      // FIXME: Using emulated TLS LLVM doesn't respect external TLS data.
+      // By passing itself as the argument to __emutls_get_address, it can
+      // return a pointer to the current thread's _Init_thread_epoch.
+      // This obviously handles only one case, and would need to be rethought
+      // to properly support extern __declspec(thread), though hopefully that
+      // construct is dubious enough to never be used .
+      m_Executor->addSymbol("__emutls_v._Init_thread_epoch",
+          utils::FunctionToVoidPtr(&__emutls_get_address), true);
+#endif
     }
 
     // Disable suggestions for ROOT

interpreter/cling/lib/Utils/EmuTLS.cpp

@@ -350,6 +350,14 @@ emutls_get_address_array(uintptr_t index) {
 }
 
 extern "C" void* __emutls_get_address(__emutls_control* control) {
+#ifdef _WIN32
+    // FIXME: Using emulated TLS LLVM doesn't respect external TLS data.
+    // To get arround this Interpreter::Initialize binds
+    // "__emutls_v._Init_thread_epoch" to &__emutls_get_address to mark that
+    // the current thread's _Init_thread_epoch should be returned.
+    if (reinterpret_cast<void*>(control) == cling::utils::FunctionToVoidPtr(&__emutls_get_address))
+      return &_Init_thread_epoch;
+#endif
     uintptr_t index = emutls_get_index(control);
     emutls_address_array* array = emutls_get_address_array(index--);
     if (array->data[index] == NULL)

interpreter/cling/test/CodeGeneration/TLSVars.C

@@ -6,7 +6,7 @@
 // LICENSE.TXT for details.
 //------------------------------------------------------------------------------
 
-// RUN: cat %s | %cling -Xclang -verify | FileCheck %s
+// RUN: cat %s | %cling -Xclang -verify 2>&1 | FileCheck %s
 
 // Test whether the TLS data is properly handled
 
@@ -17,10 +17,10 @@
 #include <stdlib.h>
 
 thread_local unsigned int TLSCounter = 1;
-std::mutex WriteMutex;
+// std::mutex WriteMutex;
 
 static void WriteValue(const char* Name, unsigned Val) {
-  std::lock_guard<std::mutex> Lock(WriteMutex);
+  // std::lock_guard<std::mutex> Lock(WriteMutex);
   printf("TLSCounter for '%s' : %u\n", Name, Val);
 }
 
@@ -45,10 +45,36 @@ WriteValue("main", TLSCounter);
 
 
 // CHECK: TLSCounter for 'A' : 2
-// CHECK: TLSCounter for 'B' : 2
-// CHECK: TLSCounter for '10' : 12
-// CHECK: TLSCounter for '5' : 7
-// CHECK: TLSCounter for 'main' : 1
+// CHECK-NEXT: TLSCounter for 'B' : 2
+// CHECK-NEXT: TLSCounter for '10' : 12
+// CHECK-NEXT: TLSCounter for '5' : 7
+// CHECK-NEXT: TLSCounter for 'main' : 1
+
+// Below is predominately for Windows
+struct TERD {
+    const char *Name;
+    TERD(const char *N) : Name(N) { printf("TERD::TERD::%s\n", Name); }
+    ~TERD() { printf("TERD::~TERD::%s\n", Name); }
+};
+static TERD& inst01() {
+    static TERD st01("inst01");
+    return st01;
+}
+static TERD& inst02() {
+    static TERD st02("inst02");
+    return st02;
+}
+
+inst01();
+// CHECK-NEXT: TERD::TERD::inst01
+std::thread(&inst01).join();
+
+std::thread(&inst02).join();
+// CHECK-NEXT: TERD::TERD::inst02
+inst02();
 
 // expected-no-diagnostics
 .q
+
+// CHECK-NEXT: TERD::~TERD::inst02
+// CHECK-NEXT: TERD::~TERD::inst01