[Pl-seminar] 11/04: Francesco Zappa Nardelli, Programming languages and concurrency: still tricky

[Vincent St-Amour]

NUPRL Seminar presents

Francesco Zappa Nardelli
INRIA

1:30 - 3:00
Tuesday, 11/04 (non-standard day)
Room 366 WVH (http://www.ccs.neu.edu/home/wand/directions.html)


Programming languages and concurrency: still tricky

Abstract:
We will explore together the remarkable and disturbing fact that,
currently, there is no really satisfactory proposal for the semantics of
a general-purpose shared-memory concurrent programming language.  Flaws
in the Java memory model are already known, we will focus instead on the
recent C11 standard.  By leveraging the semantics of low-level relaxed
atomic accesses (which allows programmers to take full advantage of
weakly-ordered memory operations) we will show that, among other
dreadful consequences, the C11 standard does not permit many common
source-to-source program transformations (such as expression
linearisation and “roach motel” reorderings) that modern compilers
perform and that are deemed to be correct.  We will consider and
evaluate a number of possible local fixes, some strengthening and some
weakening the model.