'Feng Xiao' via Protocol Buffers wrote:
> Can you help to do this? We'll probably need some changes to the patch but
> as we can't test it in the relevant platforms the code review is better to
> be initiated by someone who can make the change and test the change.
>
> It's very simple to create such a code review request. Just run a upload.py
> script in svn directory with the patch:
> https://codereview.appspot.com/use_uploadpy
OK, I've attempted to upload the code review request:
https://codereview.appspot.com/129490043/
I've also attached a plain copy of the patch exported from my git
repository.
--
Robert Edmonds
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>From 91f4a0ef6e84928d8464f9f3c804d9b8fbd14bb8 Mon Sep 17 00:00:00 2001
From: "Robert S. Edmonds" <edmo...@debian.org>
Date: Thu, 21 Aug 2014 16:03:52 -0400
Subject: [PATCH] Add generic GCC >= 4.7 support for atomic operations
This is useful for architectures where no specialized code has been
written.
This squashes the two patches submitted to the upstream bug tracker and
rewrites the architecture detection logic in platform_macros.h. The
original logic was fragile and would emit a #error on architectures that
were not explicitly detected, as the upstream protobuf release lacks a
generic atomic implementation. With gcc >= 4.7 and a generic atomic
implementation we only need to be able to tell 64-bit vs. 32-bit in
order to set GOOGLE_PROTOBUF_ARCH_64_BIT correctly (in fact, protobuf
does not even appear to use GOOGLE_PROTOBUF_ARCH_32_BIT).
It should not be necessary to add additional architecture detection
logic to platform_macros.h for Debian architectures not supported by
upstream protobuf, as we should fall back to the generic atomic
implementation. Theoretically, since we are willing to Build-Depend on
gcc >= 4.7 we might be able to use the same generic gcc implementation
across all architectures and do away with the architecture-specific
implementations entirely, but that would be a larger and more intrusive
patch.
This is based on a patch by Red Hat. We keep the generic atomic
implementation as-is, but rewrite the detection logic.
Author: Stanislav Ochotnicky <sochotni...@redhat.com>
Bug: https://code.google.com/p/protobuf/issues/detail?id=488
Last-Updated: 2014-08-21
---
src/Makefile.am | 1 +
src/google/protobuf/stubs/atomicops.h | 2 +
.../stubs/atomicops_internals_generic_gcc.h | 139 +++++++++++++++++++++
src/google/protobuf/stubs/platform_macros.h | 7 ++
4 files changed, 149 insertions(+)
create mode 100644 src/google/protobuf/stubs/atomicops_internals_generic_gcc.h
diff --git a/src/Makefile.am b/src/Makefile.am
index 9592f6f..36d09e5 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -43,6 +43,7 @@ nobase_include_HEADERS = \
google/protobuf/stubs/atomicops_internals_arm64_gcc.h \
google/protobuf/stubs/atomicops_internals_arm_qnx.h \
google/protobuf/stubs/atomicops_internals_atomicword_compat.h \
+ google/protobuf/stubs/atomicops_internals_generic_gcc.h \
google/protobuf/stubs/atomicops_internals_macosx.h \
google/protobuf/stubs/atomicops_internals_mips_gcc.h \
google/protobuf/stubs/atomicops_internals_pnacl.h \
diff --git a/src/google/protobuf/stubs/atomicops.h b/src/google/protobuf/stubs/atomicops.h
index 0847490..742549d 100644
--- a/src/google/protobuf/stubs/atomicops.h
+++ b/src/google/protobuf/stubs/atomicops.h
@@ -192,6 +192,8 @@ GOOGLE_PROTOBUF_ATOMICOPS_ERROR
#include <google/protobuf/stubs/atomicops_internals_mips_gcc.h>
#elif defined(__native_client__)
#include <google/protobuf/stubs/atomicops_internals_pnacl.h>
+#elif (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4))
+#include <google/protobuf/stubs/atomicops_internals_generic_gcc.h>
#else
GOOGLE_PROTOBUF_ATOMICOPS_ERROR
#endif
diff --git a/src/google/protobuf/stubs/atomicops_internals_generic_gcc.h b/src/google/protobuf/stubs/atomicops_internals_generic_gcc.h
new file mode 100644
index 0000000..3fc2a9b
--- /dev/null
+++ b/src/google/protobuf/stubs/atomicops_internals_generic_gcc.h
@@ -0,0 +1,139 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2013 Red Hat Inc. All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * 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.
+// * Neither the name of Red Hat Inc. 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
+// OWNER OR 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.
+
+// This file is an internal atomic implementation, use atomicops.h instead.
+
+#ifndef GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_GENERIC_GCC_H_
+#define GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_GENERIC_GCC_H_
+
+namespace google {
+namespace protobuf {
+namespace internal {
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ __atomic_compare_exchange_n(ptr, &old_value, new_value, true,
+ __ATOMIC_RELAXED, __ATOMIC_RELAXED);
+ return old_value;
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+ Atomic32 new_value) {
+ return __atomic_exchange_n(ptr, new_value, __ATOMIC_RELAXED);
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+ Atomic32 increment) {
+ return __atomic_add_fetch(ptr, increment, __ATOMIC_RELAXED);
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+ Atomic32 increment) {
+ return __atomic_add_fetch(ptr, increment, __ATOMIC_SEQ_CST);
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ __atomic_compare_exchange(ptr, &old_value, &new_value, true,
+ __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE);
+ return old_value;
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value) {
+ __atomic_compare_exchange_n(ptr, &old_value, new_value, true,
+ __ATOMIC_RELEASE, __ATOMIC_ACQUIRE);
+ return old_value;
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+ __atomic_store_n(ptr, value, __ATOMIC_RELAXED);
+}
+
+inline void MemoryBarrier() {
+ __sync_synchronize();
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+ __atomic_store_n(ptr, value, __ATOMIC_ACQUIRE);
+}
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+ __atomic_store_n(ptr, value, __ATOMIC_RELEASE);
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+ return __atomic_load_n(ptr, __ATOMIC_RELAXED);
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+ return __atomic_load_n(ptr, __ATOMIC_ACQUIRE);
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+ return __atomic_load_n(ptr, __ATOMIC_RELEASE);
+}
+
+#ifdef __LP64__
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+ __atomic_store_n(ptr, value, __ATOMIC_RELEASE);
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+ return __atomic_load_n(ptr, __ATOMIC_ACQUIRE);
+}
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ __atomic_compare_exchange_n(ptr, &old_value, new_value, true,
+ __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE);
+ return old_value;
+}
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value) {
+ __atomic_compare_exchange_n(ptr, &old_value, new_value, true,
+ __ATOMIC_RELAXED, __ATOMIC_RELAXED);
+ return old_value;
+}
+
+#endif // defined(__LP64__)
+
+} // namespace internal
+} // namespace protobuf
+} // namespace google
+
+#endif // GOOGLE_PROTOBUF_ATOMICOPS_INTERNALS_GENERIC_GCC_H_
diff --git a/src/google/protobuf/stubs/platform_macros.h b/src/google/protobuf/stubs/platform_macros.h
index 8abfd0c..6d42c5e 100644
--- a/src/google/protobuf/stubs/platform_macros.h
+++ b/src/google/protobuf/stubs/platform_macros.h
@@ -60,6 +60,13 @@
#elif defined(__ppc__)
#define GOOGLE_PROTOBUF_ARCH_PPC 1
#define GOOGLE_PROTOBUF_ARCH_32_BIT 1
+#elif defined(__GNUC__) && (((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4))
+// We fallback to the generic GCC >= 4.7 implementation in atomicops.h
+# if __LP64__
+# define GOOGLE_PROTOBUF_ARCH_64_BIT 1
+# else
+# define GOOGLE_PROTOBUF_ARCH_32_BIT 1
+# endif
#else
#error Host architecture was not detected as supported by protobuf
#endif
--
2.0.0
