Contribution of PowerPC port (continuation of 422063005) - AIX Common1

src/base/atomicops.h

 // Copyright 2010 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.
 
 // 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
@@ skipping 38 matching lines @@
 // means Atomic64 and AtomicWord should be the same type on 64-bit.
 #if defined(__ILP32__)
 typedef int64_t Atomic64;
 #else
 typedef intptr_t Atomic64;
 #endif  // defined(V8_HOST_ARCH_64_BIT)
 #endif  // defined(__native_client__)
 
 // Use AtomicWord for a machine-sized pointer.  It will use the Atomic32 or
 // Atomic64 routines below, depending on your architecture.
+#if V8_OS_AIX && V8_HOST_ARCH_32_BIT
+typedef Atomic32 AtomicWord;

[Sven Panne, 2015/01/27 11:47:05]

Hmmm, why do we need this?

[michael_dawson, 2015/01/29 00:08:29]

It looks like this was to deal with the case mentioned in
src/base/atomicops_internals_atomicword_compat.h. The description in that file
is:

// AtomicWord is a synonym for intptr_t, and Atomic32 is a synonym for int32,
// which in turn means int. On some LP32 platforms, intptr_t is an int, but
// on others, it's a long. When AtomicWord and Atomic32 are based on different
// fundamental types, their pointers are incompatible.
//
// This file defines function overloads to allow both AtomicWord and Atomic32
// data to be used with this interface.


Given that there is an existing solution in
src/base/atomicops_internals_atomicword_compat.h I'll enable that for AIX and
remove the specialization of the typedef for AIX.

+#else
 typedef intptr_t AtomicWord;
+#endif
 
 // 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"
 //
@@ skipping 90 matching lines @@
 #error "Atomic operations are not supported on your platform"
 #endif
 
 // On some platforms we need additional declarations to make
 // AtomicWord compatible with our other Atomic* types.
 #if defined(__APPLE__) || defined(__OpenBSD__)
 #include "src/base/atomicops_internals_atomicword_compat.h"
 #endif
 
 #endif  // V8_BASE_ATOMICOPS_H_