First draft of the sh4 port

src/atomicops_internals_sh4_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_
+#ifndef V8_ATOMICOPS_INTERNALS_SH4_GCC_H_
+#define V8_ATOMICOPS_INTERNALS_SH4_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;
+  return __sync_val_compare_and_swap(ptr, old_value, new_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;
+  return __sync_lock_test_and_set(ptr, new_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.
-  }
+  return __sync_add_and_fetch(const_cast<Atomic32*>(ptr), increment);
 }
 
 inline Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
-  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+  Atomic32 value = NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+  MemoryBarrier();
+  return value;
 }
 
 inline Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                        Atomic32 old_value,
                                        Atomic32 new_value) {
+  MemoryBarrier();
   return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
 }
 
+
 inline void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value) {
   *ptr = value;
 }
 
+
 inline void MemoryBarrier() {
-  pLinuxKernelMemoryBarrier();
+  __sync_synchronize();
 }
 
+
 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_
+#endif  // V8_ATOMICOPS_INTERNALS_SH4_GCC_H_