Update V8 to r6101 as required by WebKit r74534
Change-Id: I7f84af8dd732f11898fd644b2c2b1538914cb78d
diff --git a/src/atomicops.h b/src/atomicops.h
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+++ b/src/atomicops.h
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+// Copyright 2010 the V8 project authors. All rights reserved.
+// 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 Google 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.
+
+// The routines exported by this module are subtle. If you use them, even if
+// you get the code right, it will depend on careful reasoning about atomicity
+// and memory ordering; it will be less readable, and harder to maintain. If
+// you plan to use these routines, you should have a good reason, such as solid
+// evidence that performance would otherwise suffer, or there being no
+// alternative. You should assume only properties explicitly guaranteed by the
+// specifications in this file. You are almost certainly _not_ writing code
+// just for the x86; if you assume x86 semantics, x86 hardware bugs and
+// implementations on other archtectures will cause your code to break. If you
+// do not know what you are doing, avoid these routines, and use a Mutex.
+//
+// It is incorrect to make direct assignments to/from an atomic variable.
+// You should use one of the Load or Store routines. The NoBarrier
+// versions are provided when no barriers are needed:
+// NoBarrier_Store()
+// NoBarrier_Load()
+// Although there are currently no compiler enforcement, you are encouraged
+// to use these.
+//
+
+#ifndef V8_ATOMICOPS_H_
+#define V8_ATOMICOPS_H_
+
+#include "../include/v8.h"
+#include "globals.h"
+
+namespace v8 {
+namespace internal {
+
+typedef int32_t Atomic32;
+#ifdef V8_HOST_ARCH_64_BIT
+// We need to be able to go between Atomic64 and AtomicWord implicitly. This
+// means Atomic64 and AtomicWord should be the same type on 64-bit.
+#if defined(__APPLE__)
+// MacOS is an exception to the implicit conversion rule above,
+// because it uses long for intptr_t.
+typedef int64_t Atomic64;
+#else
+typedef intptr_t Atomic64;
+#endif
+#endif
+
+// Use AtomicWord for a machine-sized pointer. It will use the Atomic32 or
+// Atomic64 routines below, depending on your architecture.
+typedef intptr_t AtomicWord;
+
+// Atomically execute:
+// result = *ptr;
+// if (*ptr == old_value)
+// *ptr = new_value;
+// return result;
+//
+// I.e., replace "*ptr" with "new_value" if "*ptr" used to be "old_value".
+// Always return the old value of "*ptr"
+//
+// This routine implies no memory barriers.
+Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value);
+
+// Atomically store new_value into *ptr, returning the previous value held in
+// *ptr. This routine implies no memory barriers.
+Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr, Atomic32 new_value);
+
+// Atomically increment *ptr by "increment". Returns the new value of
+// *ptr with the increment applied. This routine implies no memory barriers.
+Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr, Atomic32 increment);
+
+Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+ Atomic32 increment);
+
+// These following lower-level operations are typically useful only to people
+// implementing higher-level synchronization operations like spinlocks,
+// mutexes, and condition-variables. They combine CompareAndSwap(), a load, or
+// a store with appropriate memory-ordering instructions. "Acquire" operations
+// ensure that no later memory access can be reordered ahead of the operation.
+// "Release" operations ensure that no previous memory access can be reordered
+// after the operation. "Barrier" operations have both "Acquire" and "Release"
+// semantics. A MemoryBarrier() has "Barrier" semantics, but does no memory
+// access.
+Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value);
+Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+ Atomic32 old_value,
+ Atomic32 new_value);
+
+void MemoryBarrier();
+void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value);
+void Acquire_Store(volatile Atomic32* ptr, Atomic32 value);
+void Release_Store(volatile Atomic32* ptr, Atomic32 value);
+
+Atomic32 NoBarrier_Load(volatile const Atomic32* ptr);
+Atomic32 Acquire_Load(volatile const Atomic32* ptr);
+Atomic32 Release_Load(volatile const Atomic32* ptr);
+
+// 64-bit atomic operations (only available on 64-bit processors).
+#ifdef V8_HOST_ARCH_64_BIT
+Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value);
+Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr, Atomic64 new_value);
+Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
+Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
+
+Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value);
+Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+ Atomic64 old_value,
+ Atomic64 new_value);
+void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value);
+void Acquire_Store(volatile Atomic64* ptr, Atomic64 value);
+void Release_Store(volatile Atomic64* ptr, Atomic64 value);
+Atomic64 NoBarrier_Load(volatile const Atomic64* ptr);
+Atomic64 Acquire_Load(volatile const Atomic64* ptr);
+Atomic64 Release_Load(volatile const Atomic64* ptr);
+#endif // V8_HOST_ARCH_64_BIT
+
+} } // namespace v8::internal
+
+// Include our platform specific implementation.
+#if defined(_MSC_VER) && \
+ (defined(V8_HOST_ARCH_IA32) || defined(V8_HOST_ARCH_X64))
+#include "atomicops_internals_x86_msvc.h"
+#elif defined(__APPLE__) && \
+ (defined(V8_HOST_ARCH_IA32) || defined(V8_HOST_ARCH_X64))
+#include "atomicops_internals_x86_macosx.h"
+#elif defined(__GNUC__) && \
+ (defined(V8_HOST_ARCH_IA32) || defined(V8_HOST_ARCH_X64))
+#include "atomicops_internals_x86_gcc.h"
+#elif defined(__GNUC__) && defined(V8_HOST_ARCH_ARM)
+#include "atomicops_internals_arm_gcc.h"
+#else
+#error "Atomic operations are not supported on your platform"
+#endif
+
+#endif // V8_ATOMICOPS_H_