This paper was approved at the June ISO C++ meeting.

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Document number: N4070

Date: 2014-06-20

Improving the specification of the vector execution policy in Parallelism TS

by Hans-J. Boehm

Excerpt:

The Parallelism TS currently prohibits synchronization in functions called from vector algorithms, but says nothing about which standard library functions may invoke synchronization. Unfortunately, due to inline expansion, and the possibility of compiling nested functions in vector mode even if not inlined, this also applies to nested internal synchronization.

This is a very rough initial attempt at somewhat pinning this down. I expect this to generate PDTS comments. The reason to apply a rough fix now is to point out the issue, and hopefully generate much more relevant comments sooner rather than later.