[Isolates] Merge crankshaft (r5922 from bleeding_edge).

src/atomicops_internals_arm_gcc.h

+// 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.
+
+// This file is an internal atomic implementation, use atomicops.h instead.
+//
+// LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears.
+
+#ifndef V8_ATOMICOPS_INTERNALS_ARM_GCC_H_
+#define V8_ATOMICOPS_INTERNALS_ARM_GCC_H_
+
+namespace v8 {
+namespace internal {
+
+// 0xffff0fc0 is the hard coded address of a function provided by
+// the kernel which implements an atomic compare-exchange. On older
+// ARM architecture revisions (pre-v6) this may be implemented using
+// a syscall. This address is stable, and in active use (hard coded)
+// by at least glibc-2.7 and the Android C library.
+typedef Atomic32 (*LinuxKernelCmpxchgFunc)(Atomic32 old_value,
+                                           Atomic32 new_value,
+                                           volatile Atomic32* ptr);
+LinuxKernelCmpxchgFunc pLinuxKernelCmpxchg __attribute__((weak)) =
+    (LinuxKernelCmpxchgFunc) 0xffff0fc0;
+
+typedef void (*LinuxKernelMemoryBarrierFunc)(void);
+LinuxKernelMemoryBarrierFunc pLinuxKernelMemoryBarrier __attribute__((weak)) =
+    (LinuxKernelMemoryBarrierFunc) 0xffff0fa0;
+
+
+inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
+                                         Atomic32 old_value,
+                                         Atomic32 new_value) {
+  Atomic32 prev_value = *ptr;
+  do {
+    if (!pLinuxKernelCmpxchg(old_value, new_value,
+                             const_cast<Atomic32*>(ptr))) {
+      return old_value;
+    }
+    prev_value = *ptr;
+  } while (prev_value == old_value);
+  return prev_value;
+}
+
+inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
+                                         Atomic32 new_value) {
+  Atomic32 old_value;
+  do {
+    old_value = *ptr;
+  } while (pLinuxKernelCmpxchg(old_value, new_value,
+                               const_cast<Atomic32*>(ptr)));
+  return old_value;
+}
+
+inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  return Barrier_AtomicIncrement(ptr, increment);
+}
+
+inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
+                                        Atomic32 increment) {
+  for (;;) {
+    // Atomic exchange the old value with an incremented one.
+    Atomic32 old_value = *ptr;
+    Atomic32 new_value = old_value + increment;
+    if (pLinuxKernelCmpxchg(old_value, new_value,
+                            const_cast<Atomic32*>(ptr)) == 0) {
+      // The exchange took place as expected.
+      return new_value;
+    }
+    // Otherwise, *ptr changed mid-loop and we need to retry.
+  }
+}
+
+inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
+                                       Atomic32 old_value,
+                                       Atomic32 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
+  *ptr = value;
+}
+
+inline void MemoryBarrier() {
+  pLinuxKernelMemoryBarrier();
+}
+
+inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
+  *ptr = value;
+  MemoryBarrier();
+}
+
+inline void Release_Store(volatile Atomic32* ptr, Atomic32 value) {
+  MemoryBarrier();
+  *ptr = value;
+}
+
+inline Atomic32 NoBarrier_Load(volatile const Atomic32* ptr) {
+  return *ptr;
+}
+
+inline Atomic32 Acquire_Load(volatile const Atomic32* ptr) {
+  Atomic32 value = *ptr;
+  MemoryBarrier();
+  return value;
+}
+
+inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
+  MemoryBarrier();
+  return *ptr;
+}
+
+} }  // namespace v8::internal
+
+#endif  // V8_ATOMICOPS_INTERNALS_ARM_GCC_H_