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From: Alexander Terekhov <terekhov@web.de>
Newsgroups: comp.std.c,comp.lang.c,comp.lang.c++,comp.programming.threads
Subject: Re: The threading specs in the standard...
Date: Wed, 03 Aug 2011 15:50:41 +0200
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Xref: x330-a1.tempe.blueboxinc.net comp.std.c:747 comp.lang.c:9005 comp.lang.c++:8430 comp.programming.threads:484

FYI:

http://www.cl.cam.ac.uk/~pes20/cppppc/top.pdf
("Clarifying and compiling C/C++ concurrency: from C++0x to POWER")

"Abstract

The upcoming C and C++ revised standards add concurrency to
the languages, for the first time, in the form of a subtle relaxed
memory model (the C++0x model). This aims to permit compiler
optimisation and to accommodate the differing relaxed-memory
behaviours of mainstream multiprocessors, combining simple semantics
for most code with high-performance low-level atomics for
concurrency libraries. We make two contributions:
We first establish two simpler but provably equivalent models
for C++0x, one for the full language and another for the subset
without consume operations. Subsetting further to the fragment
without low-level atomics, we identify a subtlety arising from
atomic initialisation.
We then prove our main result, the correctness of a proposed
compilation scheme of the C++0x concurrency primitives
to POWER assembly, having noted that an earlier proposal was
flawed. (The main ideas apply also to ARM, which has a similar
relaxed memory architecture.)
This should inform the ongoing development of production
compilers for C++0x and C1x, clarifies what properties of the
machine architecture are required, and builds confidence in the
C++0x and POWER semantics."

regards,
alexander.