Provide implementations of atomic operations for gcc on PowerPC.

Outline

Purpose
Classes
Description

Purpose

Provide implementations of atomic operations for gcc on PowerPC

Classes

bsls::AtomicOperations_POWERPC_ALL_GCC: atomics for gcc on PowerPC

Description

This component provides classes necessary to implement atomics on the PowerPC platform in 32bit/64bit mode with the GCC compiler. The classes are for private use only. See bsls_atomicoperations and bsls_atomic for the public interface to atomics.

bsls_atomicoperations_all_all_gccintrinsics.h is used for gcc 4.7+ and provides C++11 atomics. The implementation herein is intended for earlier versions of gcc and will work correctly for 64-bit programs, as well as for 32-bit programs on AIX 6 or better, where AIX kernel saves and restores 64-bit registers across context switches and interrupts, even in 32-bit programs. According to IBM developers, this guarantee is not provided by the 32-bit ABI when running Linux kernel on POWER hardware, and therefore 64-bit atomic operations using gcc __sync_* intrinsics might not operate properly in some circumstances on Linux on POWER. If running on Linux on POWER, it is highly recommended that gcc 4.7+ be used, such as the IBM Advanced Toolchain (AT) which currently provides gcc 4.8.3 for POWER, or the RedHat Developer Toolset (DTS) for POWER.

IMPLEMENTATION NOTE: there are likely excess explicit barriers since gcc __sync_* intrinsics may provide their own barriers