6 files changed, 74 insertions, 9 deletions
diff --git a/src/corelib/global/global.pri b/src/corelib/global/global.pri
index dd846955f6..6a8948822c 100644
--- a/src/corelib/global/global.pri
+++ b/src/corelib/global/global.pri
@@ -28,8 +28,9 @@ SOURCES += \
 	global/qmalloc.cpp \
         global/qnumeric.cpp \
         global/qlogging.cpp \
-        global/qhooks.cpp \
-        global/qversiontagging.cpp
+        global/qhooks.cpp
+
+VERSIONTAGGING_SOURCES = global/qversiontagging.cpp
 
 # qlibraryinfo.cpp includes qconfig.cpp
 INCLUDEPATH += $$QT_BUILD_TREE/src/corelib/global
@@ -63,3 +64,21 @@ journald {
 syslog {
     DEFINES += QT_USE_SYSLOG
 }
+
+gcc:ltcg {
+    versiontagging_compiler.commands = $$QMAKE_CXX -c $(CXXFLAGS) $(INCPATH)
+
+    # Disable LTO, as the symbols disappear somehow under GCC
+    versiontagging_compiler.commands += -fno-lto
+
+    versiontagging_compiler.commands += -o ${QMAKE_FILE_OUT} ${QMAKE_FILE_IN}
+    versiontagging_compiler.dependency_type = TYPE_C
+    versiontagging_compiler.output = ${QMAKE_VAR_OBJECTS_DIR}${QMAKE_FILE_BASE}$${first(QMAKE_EXT_OBJ)}
+    versiontagging_compiler.input = VERSIONTAGGING_SOURCES
+    versiontagging_compiler.variable_out = OBJECTS
+    versiontagging_compiler.name = compiling[versiontagging] ${QMAKE_FILE_IN}
+    silent: versiontagging_compiler.commands = @echo compiling[versiontagging] ${QMAKE_FILE_IN} && $$versiontagging_compiler.commands
+    QMAKE_EXTRA_COMPILERS += versiontagging_compiler
+} else {
+    SOURCES += $$VERSIONTAGGING_SOURCES
+}
diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index 1ebf37d610..c5424be035 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -748,7 +748,9 @@
 #      define Q_COMPILER_TEMPLATE_ALIAS
 #    endif
 #    if __has_feature(cxx_thread_local)
-#      define Q_COMPILER_THREAD_LOCAL
+#      if !defined(__FreeBSD__) /* FreeBSD clang fails on __cxa_thread_atexit */
+#        define Q_COMPILER_THREAD_LOCAL
+#      endif
 #    endif
 #    if __has_feature(cxx_user_literals)
 #      define Q_COMPILER_UDL
@@ -1108,7 +1110,8 @@
 # define Q_DECL_NOTHROW Q_DECL_NOEXCEPT
 #endif
 
-#if defined(Q_COMPILER_ALIGNOF) && !defined(Q_ALIGNOF)
+#if defined(Q_COMPILER_ALIGNOF)
+#  undef Q_ALIGNOF
 #  define Q_ALIGNOF(x)  alignof(x)
 #endif
 
diff --git a/src/corelib/global/qendian.h b/src/corelib/global/qendian.h
index c5ff82c10a..34bb015a2f 100644
--- a/src/corelib/global/qendian.h
+++ b/src/corelib/global/qendian.h
@@ -49,6 +49,11 @@
 
 QT_BEGIN_NAMESPACE
 
+#ifdef __has_builtin
+#  define QT_HAS_BUILTIN(x)     __has_builtin(x)
+#else
+#  define QT_HAS_BUILTIN(x)     0
+#endif
 
 /*
  * ENDIAN FUNCTIONS
@@ -71,18 +76,29 @@ template <typename T> inline void qbswap(const T src, uchar *dest)
 
 // Used to implement a type-safe and alignment-safe copy operation
 // If you want to avoid the memcpy, you must write specializations for these functions
-template <typename T> inline void qToUnaligned(const T src, uchar *dest)
+template <typename T> Q_ALWAYS_INLINE void qToUnaligned(const T src, uchar *dest)
 {
     // Using sizeof(T) inside memcpy function produces internal compiler error with
     // MSVC2008/ARM in tst_endian -> use extra indirection to resolve size of T.
     const size_t size = sizeof(T);
-    memcpy(dest, &src, size);
+#if QT_HAS_BUILTIN(__builtin_memcpy)
+    __builtin_memcpy
+#else
+    memcpy
+#endif
+            (dest, &src, size);
 }
-template <typename T> inline T qFromUnaligned(const uchar *src)
+
+template <typename T> Q_ALWAYS_INLINE T qFromUnaligned(const uchar *src)
 {
     T dest;
     const size_t size = sizeof(T);
-    memcpy(&dest, src, size);
+#if QT_HAS_BUILTIN(__builtin_memcpy)
+    __builtin_memcpy
+#else
+    memcpy
+#endif
+            (&dest, src, size);
     return dest;
 }
 
diff --git a/src/corelib/global/qendian.qdoc b/src/corelib/global/qendian.qdoc
index 63d924211f..3b22dcec87 100644
--- a/src/corelib/global/qendian.qdoc
+++ b/src/corelib/global/qendian.qdoc
@@ -34,6 +34,29 @@
 */
 
 /*!
+    \internal
+    \fn T qFromUnaligned(const uchar *ptr)
+    \since 5.5
+
+    Loads a \c{T} from address \a ptr, which may be misaligned.
+
+    Use of this function avoids the undefined behavior that the C++ standard
+    otherwise attributes to unaligned loads.
+*/
+
+/*!
+    \internal
+    \fn void qToUnaligned(T t, uchar *ptr)
+    \since 4.5
+
+    Stores \a t to address \a ptr, which may be misaligned.
+
+    Use of this function avoids the undefined behavior that the C++ standard
+    otherwise attributes to unaligned stores.
+*/
+
+
+/*!
     \fn T qFromBigEndian(const uchar *src)
     \since 4.3
     \relates <QtEndian>
diff --git a/src/corelib/global/qhooks.cpp b/src/corelib/global/qhooks.cpp
index 2ec1714cd2..7b9a3db30d 100644
--- a/src/corelib/global/qhooks.cpp
+++ b/src/corelib/global/qhooks.cpp
@@ -67,7 +67,7 @@ quintptr Q_CORE_EXPORT qtHookData[] = {
     // The required sizes and offsets are tested in tests/auto/other/toolsupport.
     // When this fails and the change was intentional, adjust the test and
     // adjust this value here.
-    14
+    15
 };
 
 Q_STATIC_ASSERT(QHooks::LastHookIndex == sizeof(qtHookData) / sizeof(qtHookData[0]));
diff --git a/src/corelib/global/qsystemdetection.h b/src/corelib/global/qsystemdetection.h
index 10f9068d0a..ccf5851d18 100644
--- a/src/corelib/global/qsystemdetection.h
+++ b/src/corelib/global/qsystemdetection.h
@@ -66,6 +66,7 @@
      NETBSD   - NetBSD
      OPENBSD  - OpenBSD
      BSDI     - BSD/OS
+     INTERIX  - Interix
      IRIX     - SGI Irix
      OSF      - HP Tru64 UNIX
      SCO      - SCO OpenServer 5
@@ -172,6 +173,9 @@
 #elif defined(__bsdi__)
 #  define Q_OS_BSDI
 #  define Q_OS_BSD4
+#elif defined(__INTERIX)
+#  define Q_OS_INTERIX
+#  define Q_OS_BSD4
 #elif defined(__sgi)
 #  define Q_OS_IRIX
 #elif defined(__osf__)