[Openmp-dev] OpenMP in LLVM Multi-company Telecom Meeting Minutes June 17th

Wed Jun 17 13:46:58 PDT 2020

Next Meeting :  July 1st

  *   Opens
     *   Shilei asked what coding style should be used for openmp libraries.  Currently it is inconsistent an example is device_id
     *   Suggestion is to use llvm style coding for new code as it would involve lot of work to retroactively fix all the code.
     *   The rewrite of the device rtl should already be following llvm style.

  *   Status of OpenMP version switch to 50
     *   Of the 50 failures Islam has fixed all but 9.These are due the change in order of functions generated. https://reviews.llvm.org/D81098
     *   Ok to check the changes and address the 9 failures immediately after checkin
     *   The default without setting openmp version should also be enabled in lit test to make sure future version change in compiler will not skip the test.

  *   Function pointer mapping
     *   OpenMP spec allows function pointer to be passed from host to device.  The host pointer is never updated.
     *   The implementation can choose to lookup the device address during mapping or during use on the device.
     *   Intel to investigate the implementation.

.

  *   Variable in declare target device_type(nohost)
     *   Supporting nohost variables with standalone directives requires lot more work in compiler.
     *   Plan is to change OpenMP spec to limit variables to the scoped version of declare target variant.
     *   Deepak has opened a ticket and will drive the change in the spec.

  *   Async Support
     *   Shilei implemented support to offload target tasks which are dependent on each other and not on host to be scheduled on the device immediately.
     *   The patch can be found here https://reviews.llvm.org/D81989
     *   The dependences are handled on the device runtime with event.
     *   An optimization is to schedule dependent target tasks on the same queue so the event can be avoided,

  *   fat static library
     *   Jan is making good progress on supporting fat static archives.
     *   Support for handling archives as input to llvm-link has been added.  https://reviews.llvm.org/D81109
     *   Support for unbundling an archive of bundled object files into an archive containing the device-specific code.  https://reviews.llvm.org/D80816
     *   Working on a patch to update mlink to support archive and driver to support device-specific bitcode library.

  *   Mapper support
     *   Lingda said he does not have the time, so George has taken over and will work on the runtime support.
     *   The Clang changes have been accepted.

  *   Development activities
     *   Valentin has created tablegen file for OpenMP directives and clauses.  The patch can be found here https://reviews.llvm.org/D81736
     *   The goal is sharing a common definition between clang, flang and openmp runtime.  Currently the runtime and clang have their own definition leading to potential problems
     *   Features that are specific to a language can be controlled with flags
     *   Only downside is that now openmp library build is dependent on table gen.   The advantages of sharing code overrides the downside.

Roll Call :

Company
Attendees
8-Jan
29-Jan
12-Feb
26-Feb
11-Mar
25-Mar
8-Apr
22-Apr
6-May
3-Jun
17-Jun
AMD

Greg Rodgers

x

x
x
x
x
x

Ashwin Aji

Jan Sjodin

x

x
x

x

Ron Lieberman

x

x
x
x

x

Sameer Sahasrabuddhe

Rich Bleikamp

x
x
x
x

Jonathan Chesterfield
x
x
x
x
x
x

x
x
x
x

Salyedui Islam

x
x

Pushpinder Singh

x

Raghu

x

Ethan Stewart

x

Andrey Kasaurov

ANL
Hal Finkel

x
x
x
x
x
x

Michael Kruse

x
x
x
x
x

x
x

Johannes Doerfert
x
x
x

x
x
x
x
x

Ye Luo

x

x

x
ARM
Andrzej Warzynski

x

Francesco Petrogalli

x
x
x

x

IBM
Alexandre Eichenberger

Carlo Bertolli

Kelvin Li
x

x
x

x
x
x
x
x

Doru

Alexey Bataev
x
x
x
x
x
x
x

x
x
x
Intel
Andrey Churbanov

x
x
x
x

x

Ravi Narayanaswamy
x
x
x
x
x
x
x
x
x
x
x

Serguei Dmitriev

x

Rajiv Deodhar

Lorri Menard

Terry Wilmarth

Rao, Prem

Hansang Bae

Xinmin Tian

Sirram Aananthakrishnan

x
x

x

Jeff Hammond

x

George Rokos
x
x
x
x
x
x
x
x
x
x
x

Alex Duran

x

Micheal Klemm

x

HPE
Deepak Eachempati

x
x
x

x
x
x
x
x
x

Sunil Shrestha

x

Chi Chun Chen

x

Micron
John Leidel

Nvidia
James Beyer

ORNL
Graham Lopez

Joel Denny

x

x
x
x
x
x
x
x
x

Geoffroy Vallee

Fady Ghanim
x
x
x
x
x

Oscar Hernandez

SBU/BNL
Lingda Li

x

Jose Monlsave

Vivek Kale

x

Shilei Tian

x

x
x
TU Darmstadt
Lukas Sommer
x

x
x

x

x
x
x
BrookHavens
Abid Malik
x

x
Universidata EAFIT Colombia
Hamilton Tobon Mosquera

x
x

TI
Eric Stotzer

Univ of Novi Sad
Stefan Stipanovic

x
x
Georgia Tech
Lechen Yu

x

THD
Peter Faber

x
Individual
Stewart Ethan

x

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