Binary compatibility of Symbian ARMv5 and ARMv6 builds

Use ARMv6 atomics where available
Use OS atomics otherwise

Integrate ARMV6 atomics to Symbian builds

Use compiler defined macros to detect if ARMv6 instructions are available
This defines the QT_HAVE_ARMV6 macro, replacing the way it was defined
by the Symbian build system previously in qpainting.pri.
qatomic_symbian now uses qatomic_arm or qatomic_armv6 automatically

Port armv6 atomics to implement generic atomics interface

The inline atomics are not inlined when we build for thumb using RVCT.
So there is no performance improvement of using the "inline" versions vs
a shared version called through a function call.
The generic atomics interface is good for binary compatibility, as the
same symbols are exported in all versions now.
Changed the fallback generic atomics implementation from the unix one
to a symbian specific one using RFastLock (identical code to the windows
generic atomics, except for RFastLock replaces Win32 CRITICAL_SECTION)

Note: GCCE atomics still need porting

Tell git to ignore .lst listing files (produced by sbs/abld listing)

ARMv6 support for GCCE compiler and fallback implementation using OS

When building corelib with GCCE and -march=armv6, QT_HAVE_ARMV6 will be
defined. This patch adds copies of the asm functions in GCC syntax.

When building for the Symbian emulator, or ARMv5, then Symbian OS atomic
functions are used as a fallback - these are more efficient than the unix
atomics, and don't require data import (which the ARMv5 atomics use, but
the OS loader doesn't support fully)

Symbian OS functions are always used for QBasicAtomicInt::ref / deref,
because these are faster than the generic function in all cases.
They are machine coded for ARMv6, and are used internally by RFastLock.

Reviewed-By: axis
Reviewed-By: Brad

2 files changed, 82 insertions, 24 deletions

diff --git a/src/corelib/arch/symbian/arch.pri b/src/corelib/arch/symbian/arch.pri
index deb94b1..3ef1c9e 100644
--- a/src/corelib/arch/symbian/arch.pri
+++ b/src/corelib/arch/symbian/arch.pri
@@ -2,4 +2,4 @@
 # Symbian architecture
 #
 SOURCES +=  $$QT_ARCH_CPP/qatomic_symbian.cpp \
-            $$QT_ARCH_CPP/../generic/qatomic_generic_unix.cpp
+            $$QT_ARCH_CPP/../armv6/qatomic_generic_armv6.cpp
diff --git a/src/corelib/arch/symbian/qatomic_symbian.cpp b/src/corelib/arch/symbian/qatomic_symbian.cpp
index 8f02155..2ab5ae9 100644
--- a/src/corelib/arch/symbian/qatomic_symbian.cpp
+++ b/src/corelib/arch/symbian/qatomic_symbian.cpp
@@ -50,7 +50,7 @@ QT_BEGIN_NAMESPACE
 // This way we can report on heap cells and handles that are really not owned by anything which still exists.
 // This information can be used to detect whether memory leaks are happening, particularly if these numbers grow as the app is used more.
 // This code is placed here as it happens to make it the very last static to be destroyed in a Qt app. The
-// reason assumed is that this file appears before any other file declaring static data in the generated 
+// reason assumed is that this file appears before any other file declaring static data in the generated
 // Symbian MMP file. This particular file was chosen as it is the earliest symbian specific file.
 struct QSymbianPrintExitInfo
 {
@@ -77,37 +77,95 @@ struct QSymbianPrintExitInfo
     TInt initThreadHandleCount;
 } symbian_printExitInfo;
 
-QT_END_NAMESPACE
+//For ARMv6, the generic atomics are machine coded
+#ifndef QT_HAVE_ARMV6
 
+class QCriticalSection
+{
+public:
+        QCriticalSection()  { fastlock.CreateLocal(); }
+        ~QCriticalSection() { fastlock.Close(); }
+        void lock()         { fastlock.Wait(); }
+        void unlock()       { fastlock.Signal(); }
 
-#if defined(Q_CC_RVCT)
+private:
+        RFastLock fastlock;
+};
 
-#include "../arm/qatomic_arm.cpp"
+QCriticalSection qAtomicCriticalSection;
 
-QT_BEGIN_NAMESPACE
+Q_CORE_EXPORT
+bool QBasicAtomicInt_testAndSetOrdered(volatile int *_q_value, int expectedValue, int newValue)
+{
+    bool returnValue = false;
+    qAtomicCriticalSection.lock();
+    if (*_q_value == expectedValue) {
+        *_q_value = newValue;
+        returnValue = true;
+    }
+        qAtomicCriticalSection.unlock();
+    return returnValue;
+}
 
-Q_CORE_EXPORT __asm char q_atomic_swp(volatile char *ptr, char newval)
+Q_CORE_EXPORT
+int QBasicAtomicInt_fetchAndStoreOrdered(volatile int *_q_value, int newValue)
 {
-    add r2, pc, #0
-    bx r2
-    arm
-    swpb r2,r1,[r0]
-    mov r0, r2
-    bx lr
-    thumb
+    int returnValue;
+        qAtomicCriticalSection.lock();
+    returnValue = *_q_value;
+    *_q_value = newValue;
+        qAtomicCriticalSection.unlock();
+    return returnValue;
 }
 
-Q_CORE_EXPORT __asm int QBasicAtomicInt::fetchAndStoreOrdered(int newValue)
+Q_CORE_EXPORT
+int QBasicAtomicInt_fetchAndAddOrdered(volatile int *_q_value, int valueToAdd)
 {
-    add r2, pc, #0
-    bx r2
-    arm
-    swp r2,r1,[r0]
-    mov r0, r2
-    bx lr
-    thumb
+    int returnValue;
+        qAtomicCriticalSection.lock();
+    returnValue = *_q_value;
+    *_q_value += valueToAdd;
+        qAtomicCriticalSection.unlock();
+    return returnValue;
 }
 
-QT_END_NAMESPACE
+Q_CORE_EXPORT
+bool QBasicAtomicPointer_testAndSetOrdered(void * volatile *_q_value,
+                                           void *expectedValue,
+                                           void *newValue)
+{
+    bool returnValue = false;
+        qAtomicCriticalSection.lock();
+    if (*_q_value == expectedValue) {
+        *_q_value = newValue;
+        returnValue = true;
+    }
+        qAtomicCriticalSection.unlock();
+    return returnValue;
+}
 
-#endif // Q_CC_RVCT
+Q_CORE_EXPORT
+void *QBasicAtomicPointer_fetchAndStoreOrdered(void * volatile *_q_value, void *newValue)
+{
+    void *returnValue;
+        qAtomicCriticalSection.lock();
+    returnValue = *_q_value;
+    *_q_value = newValue;
+        qAtomicCriticalSection.unlock();
+    return returnValue;
+}
+
+Q_CORE_EXPORT
+void *QBasicAtomicPointer_fetchAndAddOrdered(void * volatile *_q_value, qptrdiff valueToAdd)
+{
+    void *returnValue;
+        qAtomicCriticalSection.lock();
+    returnValue = *_q_value;
+    *_q_value = reinterpret_cast<char *>(returnValue) + valueToAdd;
+        qAtomicCriticalSection.unlock();
+    return returnValue;
+}
+
+#endif // QT_HAVE_ARMV6
+
+QT_END_NAMESPACE