To: J3                                                     J3/21-204
From: Bill Long & Lorri Menard
Subject: Beginning Business; OpenMP report
Date: 2021-October-26

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Since the last update, the committee has completed all changes for the
OpenMP 5.2 specification, and it awaits vote by the OpenMP
Architecture Review Board (ARB). The public release will be during the
week of Super Computer (SC), as usual. As mentioned in the prior update,
this version does not add any new features.

The specification was reorganized to catch inconsistencies and remove
redundancies, and to improve maintenance going forward. There were a
few deprecations and replacement spellings of certain clauses, so that
the same name was not used for clauses that serve very different purposes
on other directives. Examples of this:

- the 'default' clause was renamed to 'otherwise' on the metadirective

- the 'to' clause was renamed to 'enter' on declare target directives

- the 'depend' clause was renamed to 'doacross' for stand-alone
  ordered directives

Also, the only syntax for specifying a linear clause with modified
list items on a declare simd directive was deprecated, and a new
syntax that permits modifiers for step and linear-type was added. For
example, linear(ref(x,y):8) should now be written as
linear(x,y:step(8),ref).

Other minor changes more recently voted in:

- The behavior of the ordered(concurrent) clause on loops with dynamic
  schedules was clarified so that implementations do not have to make
  the schedules of multiple such loops consistent.

- Clarify how == comparisons are implemented for atomic constructs
  that perform compare-and-swap atomic operations. Also, clarify how
  many times an expression operand may be evaluated for C/C++ atomic
  min/max operations.

- Clarify which directives are permitted in Fortran PURE procedures
  (allow certain forms of metadirectives, assumption directives, loop
  transformation constructs, and error directives).

- Add omp_in_explicit_task() API routine (which is simply the inverse
  of the existing omp_in_implicit_task()).

In addition to the OpenMP 5.2 specification, a 5.2 reference guide
will be also be made available for download from the OpenMP website,
and hardcopies can be obtained from the OpenMP booth at SC for people
who will be attending. The booth will include virtual booth talks and
technical discussions or questions will be facilitated via zoom as
well. There will also be an OpenMP birds of a feather session that
will be all-virtual.


There will not be a TR for 6.0 released at SC this year. Some planned
6.0 features include:

- add capability to request use of a default device based on device
  trait

- continued discussion on "free agent" threads, allowing tasks to
  execute in parallel without appear in an explicit parallel region

- support for scoped atomics then extends scope to multiple devices
  for unified memory systems

- better memory management for multiple devices

- expressing dependences for taskloop construct

- better support for specifying how Fortran array syntax should be
  parallelized on target devices


A TR for OpenMP 6.0 will be released at SC'22, a comment draft in
summer of 2023 will be released, and the official OpenMP 6.0
specification should be released at SC'23.