fix TLS alignment for Windows 8.0 or below

src/core/sys/windows/threadaux.d

@@ -319,6 +319,16 @@ public:
         return tls;
     }
 
+    // get the address of the entry in the TLS array for the current thread
+    // use C mangling to access it from msvc.c
+    extern(C) void** GetTlsEntryAdr()
+    {
+        if( void** teb = getTEB() )
+            if( void** tlsarray = cast(void**) teb[11] )
+                return tlsarray + _tls_index;
+        return null;
+    }
+
     ///////////////////////////////////////////////////////////////////
     // run rt_moduleTlsCtor in the context of the given thread
     void thread_moduleTlsCtor( uint id )

src/ldc/msvc.c

@@ -1,95 +1,178 @@
-/**
- * Implementation of support routines for synchronized blocks.
- *
- * Copyright: Copyright The LDC Developers 2012
- * License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
- * Authors:   Kai Nacke <kai@redstar.de>
- */
-
-/*          Copyright The LDC Developers 2012.
- * Distributed under the Boost Software License, Version 1.0.
- *    (See accompanying file LICENSE or copy at
- *          http://www.boost.org/LICENSE_1_0.txt)
- */
-
-/* ================================= Win32 ============================ */
-
-#if _WIN32
-
-#if _MSC_VER || __MINGW64__
-
-#include <Windows.h>
-#include <string.h>
-
-const char* _data_start__;
-const char* _data_end__;
-const char* _bss_start__;
-const char* _bss_end__;
-
-EXTERN_C IMAGE_DOS_HEADER __ImageBase;
-
-static void init_data_seg(void)
-{
-    // Get handle to this module (.exe/.dll)
-    HMODULE hModule = (HMODULE) &__ImageBase;
-    char* imageBase = (char*) hModule;
-
-    // Get the DOS header
-    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER) hModule;
-
-    // Get the address of the NT headers
-    PIMAGE_NT_HEADERS pNtHeaders = (PIMAGE_NT_HEADERS) (imageBase + pDosHeader->e_lfanew);
-
-    // After the NT headers comes the sections table
-    PIMAGE_SECTION_HEADER pSectionHeader = (PIMAGE_SECTION_HEADER) (pNtHeaders + 1);
-
-    // Iterate over all sections
-    for (int i = 0; i < pNtHeaders->FileHeader.NumberOfSections; i++)
-    {
-         BYTE* name = pSectionHeader->Name;
-         if (memcmp(name, ".data", 6) == 0)
-         {
-            _data_start__ = imageBase + pSectionHeader->VirtualAddress;
-            _data_end__ = _data_start__ + pSectionHeader->Misc.VirtualSize;
-         }
-         else if (memcmp(name, ".bss", 5) == 0)
-         {
-            _bss_start__ = imageBase + pSectionHeader->VirtualAddress;
-            _bss_end__ = _bss_start__ + pSectionHeader->Misc.VirtualSize;
-         }
-
-         pSectionHeader++;
-    }
-}
-
-
-typedef int  (__cdecl *_PF)(void);
-
-static int __cdecl ctor(void)
-{
-    init_data_seg();
-    return 0;
-}
-
-static int __cdecl dtor(void)
-{
-    return 0;
-}
-
-
-#pragma data_seg(push)
-
-#pragma section(".CRT$XIY", long, read)
-#pragma section(".CRT$XTY", long, read)
-
-#pragma data_seg(".CRT$XIY")
-__declspec(allocate(".CRT$XIY")) static _PF _ctor = &ctor;
-
-#pragma data_seg(".CRT$XTY")
-__declspec(allocate(".CRT$XTY")) static _PF _dtor = &dtor;
-
-#pragma data_seg(pop)
-#endif
-
-#endif
-
+/**
+ * Implementation of support routines for synchronized blocks.
+ *
+ * Copyright: Copyright The LDC Developers 2012
+ * License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
+ * Authors:   Kai Nacke <kai@redstar.de>
+ */
+
+/*          Copyright The LDC Developers 2012.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE or copy at
+ *          http://www.boost.org/LICENSE_1_0.txt)
+ */
+
+/* ================================= Win32 ============================ */
+
+#if _WIN32
+
+#if _MSC_VER || __MINGW64__
+
+#include <Windows.h>
+#include <string.h>
+
+const char* _data_start__;
+const char* _data_end__;
+const char* _bss_start__;
+const char* _bss_end__;
+
+EXTERN_C IMAGE_DOS_HEADER __ImageBase;
+
+static void init_data_seg(void)
+{
+    // Get handle to this module (.exe/.dll)
+    HMODULE hModule = (HMODULE) &__ImageBase;
+    char* imageBase = (char*) hModule;
+
+    // Get the DOS header
+    PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER) hModule;
+
+    // Get the address of the NT headers
+    PIMAGE_NT_HEADERS pNtHeaders = (PIMAGE_NT_HEADERS) (imageBase + pDosHeader->e_lfanew);
+
+    // After the NT headers comes the sections table
+    PIMAGE_SECTION_HEADER pSectionHeader = (PIMAGE_SECTION_HEADER) (pNtHeaders + 1);
+
+    // Iterate over all sections
+    for (int i = 0; i < pNtHeaders->FileHeader.NumberOfSections; i++)
+    {
+         BYTE* name = pSectionHeader->Name;
+         if (memcmp(name, ".data", 6) == 0)
+         {
+            _data_start__ = imageBase + pSectionHeader->VirtualAddress;
+            _data_end__ = _data_start__ + pSectionHeader->Misc.VirtualSize;
+         }
+         else if (memcmp(name, ".bss", 5) == 0)
+         {
+            _bss_start__ = imageBase + pSectionHeader->VirtualAddress;
+            _bss_end__ = _bss_start__ + pSectionHeader->Misc.VirtualSize;
+         }
+
+         pSectionHeader++;
+    }
+}
+
+
+typedef int  (__cdecl *_PF)(void);
+
+static int __cdecl ctor(void)
+{
+    init_data_seg();
+    return 0;
+}
+
+static int __cdecl dtor(void)
+{
+    return 0;
+}
+
+
+#pragma data_seg(push)
+
+#pragma section(".CRT$XIY", long, read)
+#pragma section(".CRT$XTY", long, read)
+
+#pragma data_seg(".CRT$XIY")
+__declspec(allocate(".CRT$XIY")) static _PF _ctor = &ctor;
+
+#pragma data_seg(".CRT$XTY")
+__declspec(allocate(".CRT$XTY")) static _PF _dtor = &dtor;
+
+#pragma data_seg(pop)
+
+/*********************************************************
+ * Windows before Windows 8.1 does not support TLS alignment to anything
+ *  higher than 8/16 bytes for Win32 and Win64, respectively.
+ *  Some optimizations in LLVM (e.g. using aligned XMM access) do require
+ *  higher alignments, though. In addition, the programmer can use align()
+ *  to specify even larger requirements.
+ * Fixing the alignment is done by adding a TLS callback that allocates
+ *  a new copy of the TLS segment if the current one is not aligned properly.
+ */
+
+__declspec(thread) void* originalTLS; // saves the address of the original TLS to restore it before termination
+
+extern void** GetTlsEntryAdr();
+
+BOOL WINAPI fix_tlsAlignment(HINSTANCE hModule, DWORD  fdwReason, LPVOID lpvReserved)
+{
+    if (fdwReason == DLL_PROCESS_DETACH || fdwReason == DLL_THREAD_DETACH)
+    {
+        if (originalTLS)
+        {
+            // restore original pointer
+            void** tlsAdr = GetTlsEntryAdr();
+            void* allocAdr = ((void**) *tlsAdr)[-1];
+            *tlsAdr = originalTLS;
+            HeapFree(GetProcessHeap(), 0, allocAdr);
+        }
+    }
+    else
+    {
+        // crawl through the image to find the TLS alignment
+        char* imageBase = (char*) hModule;
+        PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER) hModule;
+        PIMAGE_NT_HEADERS pNtHeaders = (PIMAGE_NT_HEADERS) (imageBase + pDosHeader->e_lfanew);
+        PIMAGE_SECTION_HEADER pSectionHeader = (PIMAGE_SECTION_HEADER) (pNtHeaders + 1);
+        PIMAGE_DATA_DIRECTORY dataDir = pNtHeaders->OptionalHeader.DataDirectory + IMAGE_DIRECTORY_ENTRY_TLS;
+        if (dataDir->VirtualAddress) // any TLS entry
+        {
+            PIMAGE_TLS_DIRECTORY tlsDir = (PIMAGE_TLS_DIRECTORY) (imageBase + dataDir->VirtualAddress);
+            int alignShift = ((tlsDir->Characteristics >> 20) & 0xf);
+
+            if (alignShift)
+            {
+                int alignmentMask = (1 << (alignShift - 1)) - 1;
+                void** tlsAdr = GetTlsEntryAdr();
+                if ((SIZE_T)*tlsAdr & alignmentMask)
+                {
+                    // this implementation does about the same as Windows 8.1.
+                    HANDLE heap = GetProcessHeap();
+                    SIZE_T tlsSize = tlsDir->EndAddressOfRawData - tlsDir->StartAddressOfRawData + tlsDir->SizeOfZeroFill;
+                    SIZE_T allocSize = tlsSize + alignmentMask + sizeof(void*);
+                    void* p = HeapAlloc(heap, 0, allocSize);
+                    if (!p)
+                        return 0;
+
+                    void* aligned = (void*) (((SIZE_T) p + alignmentMask + sizeof(PVOID)) & ~alignmentMask);
+                    void* old = *tlsAdr;
+                    ((void**) aligned)[-1] = p;    // save base pointer for freeing
+                    memcpy(aligned, old, tlsSize);
+                    *tlsAdr = aligned;
+                    originalTLS = old;
+                }
+            }
+        }
+    }
+    return 1;
+}
+
+// the C++ TLS callbacks are written to ".CRT$XLC", but actually start after ".CRT$XLA".
+//  Using ".CRT$XLB" allows this to come first in the array of TLS callbacks. This
+//  guarantees that pointers saved within C++ TLS callbacks are not pointing into
+//  abandoned memory
+
+typedef BOOL WINAPI _TLSCB(HINSTANCE, DWORD, LPVOID);
+
+#pragma data_seg(push)
+
+#pragma section(".CRT$XLB", long, read)
+
+#pragma data_seg(".CRT$XLB")
+__declspec(allocate(".CRT$XLB")) static _TLSCB* _pfix_tls = &fix_tlsAlignment;
+
+#pragma data_seg(pop)
+
+#endif
+
+#endif // _WIN32