Only use 64bit atomics when supported

To support Windows XP we must avoid using the 64bit variants of the
atomicIncrement/atomicDecrement operations which are only supported from
Windows 2003 and up.

This patch rolls back the minimum Win32 API version to WinNT 5.1 (32bit WinXP),
and adds a new flag to indicate the support of 64bit atomics.

The new flag is now also used to support MIPS and other architectures
without 64bit intrinsics, instead of hacking in poor support.

This also extends the atomic operations to sparc64 which was previously
skipped because it did not work with __exchange_and_add.

Task-number: QTBUG-34271
Change-Id: I21b09df3cafb7f0987a2f44c89036ff34ed34aa0
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

12 files changed, 66 insertions, 171 deletions

diff --git a/Source/JavaScriptCore/config.h b/Source/JavaScriptCore/config.h
index 4e1d2b91c..a5df3aa7a 100644
--- a/Source/JavaScriptCore/config.h
+++ b/Source/JavaScriptCore/config.h
@@ -34,15 +34,6 @@
 #endif
 
 #if OS(WINDOWS)
-
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0502
-#endif
-
-#ifndef WINVER
-#define WINVER 0x0502
-#endif
-
 // If we don't define these, they get defined in windef.h. 
 // We want to use std::min and std::max
 #define max max
diff --git a/Source/WTF/WTF.pro b/Source/WTF/WTF.pro
index 2187e6dfe..f3a77dd06 100644
--- a/Source/WTF/WTF.pro
+++ b/Source/WTF/WTF.pro
@@ -187,7 +187,6 @@ SOURCES += \
     ArrayBuffer.cpp \
     ArrayBufferView.cpp \
     Assertions.cpp \
-    Atomics.cpp \
     BitVector.cpp \
     CryptographicallyRandomNumber.cpp \
     CurrentTime.cpp \
diff --git a/Source/WTF/config.h b/Source/WTF/config.h
index 5552be3ee..175b29c7c 100644
--- a/Source/WTF/config.h
+++ b/Source/WTF/config.h
@@ -31,15 +31,6 @@
 #include <wtf/ExportMacros.h>
 
 #if OS(WINDOWS)
-
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0502
-#endif
-
-#ifndef WINVER
-#define WINVER 0x0502
-#endif
-
 // If we don't define these, they get defined in windef.h. 
 // We want to use std::min and std::max
 #define max max
diff --git a/Source/WTF/wtf/Atomics.cpp b/Source/WTF/wtf/Atomics.cpp
deleted file mode 100644
index 0feea1532..000000000
--- a/Source/WTF/wtf/Atomics.cpp
+++ /dev/null
@@ -1,110 +0,0 @@
-/*
- * Copyright (C) 2007, 2008, 2010, 2012 Apple Inc. All rights reserved.
- * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1.  Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer. 
- * 2.  Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in the
- *     documentation and/or other materials provided with the distribution. 
- * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
- *     its contributors may be used to endorse or promote products derived
- *     from this software without specific prior written permission. 
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- *
- * Note: The implementations of InterlockedIncrement and InterlockedDecrement are based
- * on atomic_increment and atomic_exchange_and_add from the Boost C++ Library. The license
- * is virtually identical to the Apple license above but is included here for completeness.
- *
- * Boost Software License - Version 1.0 - August 17th, 2003
- * 
- * Permission is hereby granted, free of charge, to any person or organization
- * obtaining a copy of the software and accompanying documentation covered by
- * this license (the "Software") to use, reproduce, display, distribute,
- * execute, and transmit the Software, and to prepare derivative works of the
- * Software, and to permit third-parties to whom the Software is furnished to
- * do so, all subject to the following:
- * 
- * The copyright notices in the Software and this entire statement, including
- * the above license grant, this restriction and the following disclaimer,
- * must be included in all copies of the Software, in whole or in part, and
- * all derivative works of the Software, unless such copies or derivative
- * works are solely in the form of machine-executable object code generated by
- * a source language processor.
- * 
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
- * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
- * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
- * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-
-#include "config.h"
-#include "Atomics.h"
-
-// Some architectures, like MIPS32, don't have GCC implementation for builtin __sync_* functions
-// with 64 bits variable size. Official GCC answer for the problem: If a target doesn't support
-// atomic operations on certain variable sizes, you are out of luck with atomicity in that case
-// (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56296). GCC >= 4.8 will support __atomic_* builtin
-// functions for this purpose for all the GCC targets, but for current compilers we have to include
-// our own implementation.
-#if COMPILER(GCC) && !defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8) && USE(LOCKFREE_THREADSAFEREFCOUNTED) && USE(PTHREADS)
-
-#include "ThreadingPrimitives.h"
-
-namespace WTF {
-
-static const size_t kSwapLockCount = 32;
-static Mutex s_swapLocks[kSwapLockCount];
-
-static inline Mutex& getSwapLock(const volatile int64_t* addr)
-{
-    return s_swapLocks[(reinterpret_cast<intptr_t>(addr) >> 3U) % kSwapLockCount];
-}
-
-static int64_t atomicStep(int64_t volatile* addend, int64_t step)
-{
-    Mutex& mutex = getSwapLock(addend);
-
-    mutex.lock();
-    int64_t value = *addend + step;
-    *addend = value;
-    mutex.unlock();
-
-    return value;
-}
-
-extern "C" {
-
-int64_t __sync_add_and_fetch_8(int64_t volatile* addend, int64_t value)
-{
-    return atomicStep(addend, value);
-}
-
-int64_t __sync_sub_and_fetch_8(int64_t volatile* addend, int64_t value)
-{
-    return atomicStep(addend, -value);
-}
-
-} // extern "C"
-
-} // namespace WTF
-
-#endif
diff --git a/Source/WTF/wtf/Atomics.h b/Source/WTF/wtf/Atomics.h
index b21d51520..ea4f55f95 100644
--- a/Source/WTF/wtf/Atomics.h
+++ b/Source/WTF/wtf/Atomics.h
@@ -78,24 +78,16 @@ extern "C" void _ReadWriteBarrier(void);
 
 namespace WTF {
 
+// 32bit atomicIncrement/atomicDecrement
 #if OS(WINDOWS)
 #define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
 
-#if OS(WINCE)
-inline int atomicIncrement(int* addend) { return InterlockedIncrement(reinterpret_cast<long*>(addend)); }
-inline int atomicDecrement(int* addend) { return InterlockedDecrement(reinterpret_cast<long*>(addend)); }
-#elif COMPILER(MINGW)
+#if OS(WINCE) || COMPILER(MINGW)
 inline int atomicIncrement(int* addend) { return InterlockedIncrement(reinterpret_cast<long*>(addend)); }
 inline int atomicDecrement(int* addend) { return InterlockedDecrement(reinterpret_cast<long*>(addend)); }
-
-inline int64_t atomicIncrement(int64_t* addend) { return InterlockedIncrement64(reinterpret_cast<long long*>(addend)); }
-inline int64_t atomicDecrement(int64_t* addend) { return InterlockedDecrement64(reinterpret_cast<long long*>(addend)); }
 #else
 inline int atomicIncrement(int volatile* addend) { return InterlockedIncrement(reinterpret_cast<long volatile*>(addend)); }
 inline int atomicDecrement(int volatile* addend) { return InterlockedDecrement(reinterpret_cast<long volatile*>(addend)); }
-
-inline int64_t atomicIncrement(int64_t volatile* addend) { return InterlockedIncrement64(reinterpret_cast<long long volatile*>(addend)); }
-inline int64_t atomicDecrement(int64_t volatile* addend) { return InterlockedDecrement64(reinterpret_cast<long long volatile*>(addend)); }
 #endif
 
 #elif OS(QNX)
@@ -115,17 +107,26 @@ inline int atomicDecrement(int volatile* addend) { return __atomic_dec(addend) -
 inline int64_t atomicIncrement(int64_t volatile* addend) { return __sync_add_and_fetch(addend, 1); }
 inline int64_t atomicDecrement(int64_t volatile* addend) { return __sync_sub_and_fetch(addend, 1); }
 
-#elif COMPILER(GCC) && !CPU(SPARC64) // sizeof(_Atomic_word) != sizeof(int) on sparc64 gcc
+#elif COMPILER(GCC)
 #define WTF_USE_LOCKFREE_THREADSAFEREFCOUNTED 1
 
 inline int atomicIncrement(int volatile* addend) { return __sync_add_and_fetch(addend, 1); }
 inline int atomicDecrement(int volatile* addend) { return __sync_sub_and_fetch(addend, 1); }
 
+#endif
+
+// 64bit atomicIncrement/atomicDecrement
+#if HAVE(ATOMICS_64BIT)
+#if COMPILER(GCC)
 inline int64_t atomicIncrement(int64_t volatile* addend) { return __sync_add_and_fetch(addend, 1); }
 inline int64_t atomicDecrement(int64_t volatile* addend) { return __sync_sub_and_fetch(addend, 1); }
-
+#elif OS(WINDOWS)
+inline int64_t atomicIncrement(int64_t volatile* addend) { return InterlockedIncrement64(reinterpret_cast<long long volatile*>(addend)); }
+inline int64_t atomicDecrement(int64_t volatile* addend) { return InterlockedDecrement64(reinterpret_cast<long long volatile*>(addend)); }
+#endif
 #endif
 
+
 #if OS(WINDOWS)
 inline bool weakCompareAndSwap(volatile unsigned* location, unsigned expected, unsigned newValue)
 {
diff --git a/Source/WTF/wtf/Platform.h b/Source/WTF/wtf/Platform.h
index 6a544fa4f..3a9b509f2 100644
--- a/Source/WTF/wtf/Platform.h
+++ b/Source/WTF/wtf/Platform.h
@@ -440,6 +440,33 @@
 #define WTF_OS_UNIX 1
 #endif
 
+#if OS(WINDOWS)
+// Minimum supported windows is Windows XP.
+// The original WinXP was NT 5.1, but Win XP 64bit was NT 5.2
+#if CPU(X86_64)
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0502
+#endif
+
+#ifndef WINVER
+#define WINVER 0x0502
+#endif
+
+#else /* !CPU(X86_64) */
+
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501
+#endif
+
+#ifndef WINVER
+#define WINVER 0x0501
+#endif
+
+#endif
+
+#endif
+
+
 /* Operating environments */
 
 /* FIXME: these are all mixes of OS, operating environment and policy choices. */
@@ -1020,6 +1047,11 @@
 #define WTF_USE_CONTENT_FILTERING 1
 #endif
 
+#if COMPILER(GCC) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)
+#define HAVE_ATOMICS_64BIT 1
+#elif OS(WINDOWS) && (_WIN32_WINNT >= 0x0502)
+#define HAVE_ATOMICS_64BIT 1
+#endif
 
 #define WTF_USE_GRAMMAR_CHECKING 1
 
diff --git a/Source/WebCore/WebCorePrefix.h b/Source/WebCore/WebCorePrefix.h
index 543f50f61..575687226 100644
--- a/Source/WebCore/WebCorePrefix.h
+++ b/Source/WebCore/WebCorePrefix.h
@@ -38,15 +38,6 @@
 #endif
 
 #if OS(WINDOWS)
-
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0502
-#endif
-
-#ifndef WINVER
-#define WINVER 0x0502
-#endif
-
 #if !USE(CURL)
 #ifndef _WINSOCKAPI_
 #define _WINSOCKAPI_ // Prevent inclusion of winsock.h in windows.h
diff --git a/Source/WebCore/config.h b/Source/WebCore/config.h
index 30bed8e6a..d0be35d94 100644
--- a/Source/WebCore/config.h
+++ b/Source/WebCore/config.h
@@ -47,15 +47,6 @@
 #endif /* __APPLE__ */
 
 #if OS(WINDOWS)
-
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0502
-#endif
-
-#ifndef WINVER
-#define WINVER 0x0502
-#endif
-
 // If we don't define these, they get defined in windef.h.
 // We want to use std::min and std::max.
 #ifndef max
diff --git a/Source/WebKit2/Platform/CoreIPC/Connection.cpp b/Source/WebKit2/Platform/CoreIPC/Connection.cpp
index b6cdf9325..e618e9d1b 100644
--- a/Source/WebKit2/Platform/CoreIPC/Connection.cpp
+++ b/Source/WebKit2/Platform/CoreIPC/Connection.cpp
@@ -348,9 +348,15 @@ PassOwnPtr<MessageEncoder> Connection::createSyncMessageEncoder(StringReference
     OwnPtr<MessageEncoder> encoder = MessageEncoder::create(messageReceiverName, messageName, destinationID);
     encoder->setIsSyncMessage(true);
 
+#if HAVE(ATOMICS_64BIT)
     // Encode the sync request ID.
     COMPILE_ASSERT(sizeof(m_syncRequestID) == sizeof(int64_t), CanUseAtomicIncrement);
     syncRequestID = atomicIncrement(reinterpret_cast<int64_t*>(&m_syncRequestID));
+#else
+    m_syncRequestLock.lock();
+    syncRequestID = ++m_syncRequestID;
+    m_syncRequestLock.unlock();
+#endif
     *encoder << syncRequestID;
 
     return encoder.release();
diff --git a/Source/WebKit2/Platform/CoreIPC/Connection.h b/Source/WebKit2/Platform/CoreIPC/Connection.h
index 50a9c9876..be1923699 100644
--- a/Source/WebKit2/Platform/CoreIPC/Connection.h
+++ b/Source/WebKit2/Platform/CoreIPC/Connection.h
@@ -254,6 +254,10 @@ private:
     Mutex m_waitForMessageMutex;
     HashMap<std::pair<std::pair<StringReference, StringReference>, uint64_t>, OwnPtr<MessageDecoder> > m_waitForMessageMap;
 
+#if !HAVE(ATOMICS_64BIT)
+    Mutex m_syncRequestLock;
+#endif
+
     // Represents a sync request for which we're waiting on a reply.
     struct PendingSyncReply {
         // The request ID.
diff --git a/Source/WebKit2/UIProcess/StatisticsRequest.cpp b/Source/WebKit2/UIProcess/StatisticsRequest.cpp
index 0fa1fb7a7..6f81ccbb3 100644
--- a/Source/WebKit2/UIProcess/StatisticsRequest.cpp
+++ b/Source/WebKit2/UIProcess/StatisticsRequest.cpp
@@ -28,7 +28,7 @@
 
 #include "ImmutableArray.h"
 #include "MutableDictionary.h"
-#include <wtf/Atomics.h>
+#include <wtf/Threading.h>
 
 namespace WebKit {
 
@@ -47,7 +47,15 @@ uint64_t StatisticsRequest::addOutstandingRequest()
 {
     static int64_t uniqueRequestID;
 
+#if HAVE(ATOMICS_64BIT)
     uint64_t requestID = atomicIncrement(&uniqueRequestID);
+#else
+    static Mutex uniqueRequestMutex;
+    uniqueRequestMutex.lock();
+    uint64_t requestID = ++uniqueRequestID;
+    uniqueRequestMutex.unlock();
+#endif
+
     m_outstandingRequests.add(requestID);
     return requestID;
 }
diff --git a/Source/WebKit2/config.h b/Source/WebKit2/config.h
index c80c29ef4..37cc06f6a 100644
--- a/Source/WebKit2/config.h
+++ b/Source/WebKit2/config.h
@@ -55,16 +55,7 @@ static const type& name() \
     return name##Value; \
 }
 
-#if defined(WIN32) || defined(_WIN32)
-
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0502
-#endif
-
-#ifndef WINVER
-#define WINVER 0x0502
-#endif
-
+#if OS(WINDOWS)
 /* If we don't define these, they get defined in windef.h. */
 /* We want to use std::min and std::max. */
 #ifndef max
@@ -87,7 +78,7 @@ static const type& name() \
 #include <CoreGraphics/CoreGraphics.h>
 #endif
 
-#endif /* defined(WIN32) || defined(_WIN32) */
+#endif /* OS(WINDOWS) */
 
 #ifdef __cplusplus