Merge google-perftools r109 (the current contents of third_party/tcmalloc/vendor)

third_party/tcmalloc/chromium/src/base/atomicops-internals-arm-gcc.h

+/* Copyright (c) 2010, Google Inc.
+ * 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.
+ *
+ * ---
+ * Author: Lei Zhang, Sasha Levitskiy
+ */
+
+// This file is an internal atomic implementation, use base/atomicops.h instead.
+//
+// LinuxKernelCmpxchg and Barrier_AtomicIncrement are from Google Gears.
+
+#ifndef BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_
+#define BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_
+
+#include <stdio.h>
+#include "base/basictypes.h"  // For COMPILE_ASSERT
+
+typedef int32_t Atomic32;
+
+namespace base {
+namespace subtle {
+
+typedef int64_t Atomic64;
+
+// 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.
+// pLinuxKernelCmpxchg has both acquire and release barrier sematincs.
+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 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 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
+                                          Atomic32 increment) {
+  return Barrier_AtomicIncrement(ptr, increment);
+}
+
+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;
+}
+
+
+// 64-bit versions are not implemented yet.
+
+inline void NotImplementedFatalError(const char *function_name) {
+  fprintf(stderr, "64-bit %s() not implemented on this platform\n",
+          function_name);
+  abort();
+}
+
+inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
+                                         Atomic64 old_value,
+                                         Atomic64 new_value) {
+  NotImplementedFatalError("NoBarrier_CompareAndSwap");
+  return 0;
+}
+
+inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
+                                         Atomic64 new_value) {
+  NotImplementedFatalError("NoBarrier_AtomicExchange");
+  return 0;
+}
+
+inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
+                                          Atomic64 increment) {
+  NotImplementedFatalError("NoBarrier_AtomicIncrement");
+  return 0;
+}
+
+inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
+                                        Atomic64 increment) {
+  NotImplementedFatalError("Barrier_AtomicIncrement");
+  return 0;
+}
+
+inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
+  NotImplementedFatalError("NoBarrier_Store");
+}
+
+inline void Acquire_Store(volatile Atomic64* ptr, Atomic64 value) {
+  NoBarrier_AtomicExchange(ptr, value);
+              // acts as a barrier in this implementation
+}
+
+inline void Release_Store(volatile Atomic64* ptr, Atomic64 value) {
+  NotImplementedFatalError("Release_Store");
+}
+
+inline Atomic64 NoBarrier_Load(volatile const Atomic64* ptr) {
+  NotImplementedFatalError("NoBarrier_Load");
+  return 0;
+}
+
+inline Atomic64 Acquire_Load(volatile const Atomic64* ptr) {
+  Atomic64 value = NoBarrier_Load(ptr);
+  return value;
+}
+
+inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
+  MemoryBarrier();
+  return NoBarrier_Load(ptr);
+}
+
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+}  // namespace base::subtle
+}  // namespace base
+
+#endif  // BASE_ATOMICOPS_INTERNALS_ARM_GCC_H_