Contribution of PowerPC port.

src/base/atomicops_internals_ppc_gcc.h

Index: src/base/atomicops_internals_ppc_gcc.h
diff --git a/src/base/atomicops_internals_mac.h b/src/base/atomicops_internals_ppc_gcc.h
similarity index 62%
copy from src/base/atomicops_internals_mac.h
copy to src/base/atomicops_internals_ppc_gcc.h
index a046872e4d0fbff487fbf89770b4fe92d2d2d031..660eb2fa8eff86bd7ee81e8ab49951fa65c8b59d 100644
--- a/src/base/atomicops_internals_mac.h
+++ b/src/base/atomicops_internals_ppc_gcc.h
@@ -1,13 +1,12 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file is an internal atomic implementation, use atomicops.h instead.
+//
 
-#ifndef V8_BASE_ATOMICOPS_INTERNALS_MAC_H_
-#define V8_BASE_ATOMICOPS_INTERNALS_MAC_H_
-
-#include <libkern/OSAtomic.h>
+#ifndef V8_BASE_ATOMICOPS_INTERNALS_PPC_H_
+#define V8_BASE_ATOMICOPS_INTERNALS_PPC_H_
 
 namespace v8 {
 namespace base {
@@ -15,15 +14,7 @@ namespace base {
 inline Atomic32 NoBarrier_CompareAndSwap(volatile Atomic32* ptr,
                                          Atomic32 old_value,
                                          Atomic32 new_value) {
-  Atomic32 prev_value;
-  do {
-    if (OSAtomicCompareAndSwap32(old_value, new_value,
-                                 const_cast<Atomic32*>(ptr))) {
-      return old_value;
-    }
-    prev_value = *ptr;
-  } while (prev_value == old_value);
-  return prev_value;
+  return(__sync_val_compare_and_swap( ptr, old_value, new_value));
 }
 
 inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
@@ -31,43 +22,38 @@ inline Atomic32 NoBarrier_AtomicExchange(volatile Atomic32* ptr,
   Atomic32 old_value;
   do {
     old_value = *ptr;
-  } while (!OSAtomicCompareAndSwap32(old_value, new_value,
-                                     const_cast<Atomic32*>(ptr)));
+  } while (__sync_bool_compare_and_swap(ptr, old_value, new_value) == false);
   return old_value;
 }
 
 inline Atomic32 NoBarrier_AtomicIncrement(volatile Atomic32* ptr,
                                           Atomic32 increment) {
-  return OSAtomicAdd32(increment, const_cast<Atomic32*>(ptr));
+  return Barrier_AtomicIncrement(ptr, increment);
 }
 
 inline Atomic32 Barrier_AtomicIncrement(volatile Atomic32* ptr,
                                         Atomic32 increment) {
-  return OSAtomicAdd32Barrier(increment, const_cast<Atomic32*>(ptr));
-}
-
-inline void MemoryBarrier() {
-  OSMemoryBarrier();
+  for (;;) {
+    Atomic32 old_value = *ptr;
+    Atomic32 new_value = old_value + increment;
+    if (__sync_bool_compare_and_swap(ptr, old_value, new_value)) {
+      return new_value;
+      // The exchange took place as expected.
+    }
+    // Otherwise, *ptr changed mid-loop and we need to retry.
+  }
 }
 
 inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  Atomic32 prev_value;
-  do {
-    if (OSAtomicCompareAndSwap32Barrier(old_value, new_value,
-                                        const_cast<Atomic32*>(ptr))) {
-      return old_value;
-    }
-    prev_value = *ptr;
-  } while (prev_value == old_value);
-  return prev_value;
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  return Acquire_CompareAndSwap(ptr, old_value, new_value);
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 inline void NoBarrier_Store(volatile Atomic8* ptr, Atomic8 value) {
@@ -78,6 +64,10 @@ inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
   *ptr = value;
 }
 
+inline void MemoryBarrier() {
+  __asm__ __volatile__("sync" : : : "memory");
+}
+
 inline void Acquire_Store(volatile Atomic32* ptr, Atomic32 value) {
   *ptr = value;
   MemoryBarrier();
@@ -107,22 +97,11 @@ inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
   return *ptr;
 }
 
-#ifdef __LP64__
-
-// 64-bit implementation on 64-bit platform
-
+#ifdef V8_TARGET_ARCH_PPC64
 inline Atomic64 NoBarrier_CompareAndSwap(volatile Atomic64* ptr,
                                          Atomic64 old_value,
                                          Atomic64 new_value) {
-  Atomic64 prev_value;
-  do {
-    if (OSAtomicCompareAndSwap64(old_value, new_value,
-                                 reinterpret_cast<volatile int64_t*>(ptr))) {
-      return old_value;
-    }
-    prev_value = *ptr;
-  } while (prev_value == old_value);
-  return prev_value;
+  return(__sync_val_compare_and_swap( ptr, old_value, new_value));
 }
 
 inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
@@ -130,42 +109,38 @@ inline Atomic64 NoBarrier_AtomicExchange(volatile Atomic64* ptr,
   Atomic64 old_value;
   do {
     old_value = *ptr;
-  } while (!OSAtomicCompareAndSwap64(old_value, new_value,
-                                     reinterpret_cast<volatile int64_t*>(ptr)));
+  } while (__sync_bool_compare_and_swap(ptr, old_value, new_value) == false);
   return old_value;
 }
 
 inline Atomic64 NoBarrier_AtomicIncrement(volatile Atomic64* ptr,
                                           Atomic64 increment) {
-  return OSAtomicAdd64(increment, reinterpret_cast<volatile int64_t*>(ptr));
+  return Barrier_AtomicIncrement(ptr, increment);
 }
 
 inline Atomic64 Barrier_AtomicIncrement(volatile Atomic64* ptr,
                                         Atomic64 increment) {
-  return OSAtomicAdd64Barrier(increment,
-                              reinterpret_cast<volatile int64_t*>(ptr));
+  for (;;) {
+    Atomic64 old_value = *ptr;
+    Atomic64 new_value = old_value + increment;
+    if (__sync_bool_compare_and_swap(ptr, old_value, new_value)) {
+      return new_value;
+      // The exchange took place as expected.
+    }
+    // Otherwise, *ptr changed mid-loop and we need to retry.
+  }
 }
 
 inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
                                        Atomic64 old_value,
                                        Atomic64 new_value) {
-  Atomic64 prev_value;
-  do {
-    if (OSAtomicCompareAndSwap64Barrier(
-        old_value, new_value, reinterpret_cast<volatile int64_t*>(ptr))) {
-      return old_value;
-    }
-    prev_value = *ptr;
-  } while (prev_value == old_value);
-  return prev_value;
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
                                        Atomic64 old_value,
                                        Atomic64 new_value) {
-  // The lib kern interface does not distinguish between
-  // Acquire and Release memory barriers; they are equivalent.
-  return Acquire_CompareAndSwap(ptr, old_value, new_value);
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
 inline void NoBarrier_Store(volatile Atomic64* ptr, Atomic64 value) {
@@ -197,8 +172,8 @@ inline Atomic64 Release_Load(volatile const Atomic64* ptr) {
   return *ptr;
 }
 
-#endif  // defined(__LP64__)
+#endif
 
 } }  // namespace v8::base
 
-#endif  // V8_BASE_ATOMICOPS_INTERNALS_MAC_H_
+#endif  // V8_BASE_ATOMICOPS_INTERNALS_PPC_GCC_H_