evalkit_internvl/share/info/libgomp.info

This is libgomp.info, produced by makeinfo version 6.8 from
libgomp.texi.

Copyright (C) 2006-2021 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover texts
being (a) (see below), and with the Back-Cover Texts being (b) (see
below).  A copy of the license is included in the section entitled "GNU
Free Documentation License".

   (a) The FSF's Front-Cover Text is:

   A GNU Manual

   (b) The FSF's Back-Cover Text is:

   You have freedom to copy and modify this GNU Manual, like GNU
software.  Copies published by the Free Software Foundation raise funds
for GNU development.
INFO-DIR-SECTION GNU Libraries
START-INFO-DIR-ENTRY
* libgomp: (libgomp).          GNU Offloading and Multi Processing Runtime Library.
END-INFO-DIR-ENTRY

   This manual documents libgomp, the GNU Offloading and Multi
Processing Runtime library.  This is the GNU implementation of the
OpenMP and OpenACC APIs for parallel and accelerator programming in
C/C++ and Fortran.

   Published by the Free Software Foundation 51 Franklin Street, Fifth
Floor Boston, MA 02110-1301 USA

   Copyright (C) 2006-2021 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover texts
being (a) (see below), and with the Back-Cover Texts being (b) (see
below).  A copy of the license is included in the section entitled "GNU
Free Documentation License".

   (a) The FSF's Front-Cover Text is:

   A GNU Manual

   (b) The FSF's Back-Cover Text is:

   You have freedom to copy and modify this GNU Manual, like GNU
software.  Copies published by the Free Software Foundation raise funds
for GNU development.


File: libgomp.info,  Node: Top,  Next: Enabling OpenMP,  Up: (dir)

Introduction
************

This manual documents the usage of libgomp, the GNU Offloading and Multi
Processing Runtime Library.  This includes the GNU implementation of the
OpenMP (https://www.openmp.org) Application Programming Interface (API)
for multi-platform shared-memory parallel programming in C/C++ and
Fortran, and the GNU implementation of the OpenACC
(https://www.openacc.org) Application Programming Interface (API) for
offloading of code to accelerator devices in C/C++ and Fortran.

   Originally, libgomp implemented the GNU OpenMP Runtime Library.
Based on this, support for OpenACC and offloading (both OpenACC and
OpenMP 4's target construct) has been added later on, and the library's
name changed to GNU Offloading and Multi Processing Runtime Library.

* Menu:

* Enabling OpenMP::            How to enable OpenMP for your applications.
* OpenMP Runtime Library Routines: Runtime Library Routines.
                               The OpenMP runtime application programming
                               interface.
* OpenMP Environment Variables: Environment Variables.
                               Influencing OpenMP runtime behavior with
                               environment variables.
* Enabling OpenACC::           How to enable OpenACC for your
                               applications.
* OpenACC Runtime Library Routines:: The OpenACC runtime application
                               programming interface.
* OpenACC Environment Variables:: Influencing OpenACC runtime behavior with
                               environment variables.
* CUDA Streams Usage::         Notes on the implementation of
                               asynchronous operations.
* OpenACC Library Interoperability:: OpenACC library interoperability with the
                               NVIDIA CUBLAS library.
* OpenACC Profiling Interface::
* The libgomp ABI::            Notes on the external ABI presented by libgomp.
* Reporting Bugs::             How to report bugs in the GNU Offloading and
                               Multi Processing Runtime Library.
* Copying::                    GNU general public license says
                               how you can copy and share libgomp.
* GNU Free Documentation License::
                               How you can copy and share this manual.
* Funding::                    How to help assure continued work for free
                               software.
* Library Index::              Index of this documentation.


File: libgomp.info,  Node: Enabling OpenMP,  Next: Runtime Library Routines,  Up: Top

1 Enabling OpenMP
*****************

To activate the OpenMP extensions for C/C++ and Fortran, the
compile-time flag '-fopenmp' must be specified.  This enables the OpenMP
directive '#pragma omp' in C/C++ and '!$omp' directives in free form,
'c$omp', '*$omp' and '!$omp' directives in fixed form, '!$' conditional
compilation sentinels in free form and 'c$', '*$' and '!$' sentinels in
fixed form, for Fortran.  The flag also arranges for automatic linking
of the OpenMP runtime library (*note Runtime Library Routines::).

   A complete description of all OpenMP directives accepted may be found
in the OpenMP Application Program Interface (https://www.openmp.org)
manual, version 4.5.


File: libgomp.info,  Node: Runtime Library Routines,  Next: Environment Variables,  Prev: Enabling OpenMP,  Up: Top

2 OpenMP Runtime Library Routines
*********************************

The runtime routines described here are defined by Section 3 of the
OpenMP specification in version 4.5.  The routines are structured in
following three parts:

* Menu:

Control threads, processors and the parallel environment.  They have C
linkage, and do not throw exceptions.

* omp_get_active_level::        Number of active parallel regions
* omp_get_ancestor_thread_num:: Ancestor thread ID
* omp_get_cancellation::        Whether cancellation support is enabled
* omp_get_default_device::      Get the default device for target regions
* omp_get_dynamic::             Dynamic teams setting
* omp_get_initial_device::      Device number of host device
* omp_get_level::               Number of parallel regions
* omp_get_max_active_levels::   Current maximum number of active regions
* omp_get_max_task_priority::   Maximum task priority value that can be set
* omp_get_max_threads::         Maximum number of threads of parallel region
* omp_get_nested::              Nested parallel regions
* omp_get_num_devices::         Number of target devices
* omp_get_num_procs::           Number of processors online
* omp_get_num_teams::           Number of teams
* omp_get_num_threads::         Size of the active team
* omp_get_proc_bind::           Whether theads may be moved between CPUs
* omp_get_schedule::            Obtain the runtime scheduling method
* omp_get_supported_active_levels:: Maximum number of active regions supported
* omp_get_team_num::            Get team number
* omp_get_team_size::           Number of threads in a team
* omp_get_thread_limit::        Maximum number of threads
* omp_get_thread_num::          Current thread ID
* omp_in_parallel::             Whether a parallel region is active
* omp_in_final::                Whether in final or included task region
* omp_is_initial_device::       Whether executing on the host device
* omp_set_default_device::      Set the default device for target regions
* omp_set_dynamic::             Enable/disable dynamic teams
* omp_set_max_active_levels::   Limits the number of active parallel regions
* omp_set_nested::              Enable/disable nested parallel regions
* omp_set_num_threads::         Set upper team size limit
* omp_set_schedule::            Set the runtime scheduling method

Initialize, set, test, unset and destroy simple and nested locks.

* omp_init_lock::            Initialize simple lock
* omp_set_lock::             Wait for and set simple lock
* omp_test_lock::            Test and set simple lock if available
* omp_unset_lock::           Unset simple lock
* omp_destroy_lock::         Destroy simple lock
* omp_init_nest_lock::       Initialize nested lock
* omp_set_nest_lock::        Wait for and set simple lock
* omp_test_nest_lock::       Test and set nested lock if available
* omp_unset_nest_lock::      Unset nested lock
* omp_destroy_nest_lock::    Destroy nested lock

Portable, thread-based, wall clock timer.

* omp_get_wtick::            Get timer precision.
* omp_get_wtime::            Elapsed wall clock time.

Support for event objects.

* omp_fulfill_event::        Fulfill and destroy an OpenMP event.


File: libgomp.info,  Node: omp_get_active_level,  Next: omp_get_ancestor_thread_num,  Up: Runtime Library Routines

2.1 'omp_get_active_level' - Number of parallel regions
=======================================================

_Description_:
     This function returns the nesting level for the active parallel
     blocks, which enclose the calling call.

_C/C++_
     _Prototype_:   'int omp_get_active_level(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_active_level()'

_See also_:
     *note omp_get_level::, *note omp_get_max_active_levels::, *note
     omp_set_max_active_levels::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.20.


File: libgomp.info,  Node: omp_get_ancestor_thread_num,  Next: omp_get_cancellation,  Prev: omp_get_active_level,  Up: Runtime Library Routines

2.2 'omp_get_ancestor_thread_num' - Ancestor thread ID
======================================================

_Description_:
     This function returns the thread identification number for the
     given nesting level of the current thread.  For values of LEVEL
     outside zero to 'omp_get_level' -1 is returned; if LEVEL is
     'omp_get_level' the result is identical to 'omp_get_thread_num'.

_C/C++_
     _Prototype_:   'int omp_get_ancestor_thread_num(int level);'

_Fortran_:
     _Interface_:   'integer function omp_get_ancestor_thread_num(level)'
                    'integer level'

_See also_:
     *note omp_get_level::, *note omp_get_thread_num::, *note
     omp_get_team_size::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.18.


File: libgomp.info,  Node: omp_get_cancellation,  Next: omp_get_default_device,  Prev: omp_get_ancestor_thread_num,  Up: Runtime Library Routines

2.3 'omp_get_cancellation' - Whether cancellation support is enabled
====================================================================

_Description_:
     This function returns 'true' if cancellation is activated, 'false'
     otherwise.  Here, 'true' and 'false' represent their
     language-specific counterparts.  Unless 'OMP_CANCELLATION' is set
     true, cancellations are deactivated.

_C/C++_:
     _Prototype_:   'int omp_get_cancellation(void);'

_Fortran_:
     _Interface_:   'logical function omp_get_cancellation()'

_See also_:
     *note OMP_CANCELLATION::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.9.


File: libgomp.info,  Node: omp_get_default_device,  Next: omp_get_dynamic,  Prev: omp_get_cancellation,  Up: Runtime Library Routines

2.4 'omp_get_default_device' - Get the default device for target regions
========================================================================

_Description_:
     Get the default device for target regions without device clause.

_C/C++_:
     _Prototype_:   'int omp_get_default_device(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_default_device()'

_See also_:
     *note OMP_DEFAULT_DEVICE::, *note omp_set_default_device::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.30.


File: libgomp.info,  Node: omp_get_dynamic,  Next: omp_get_initial_device,  Prev: omp_get_default_device,  Up: Runtime Library Routines

2.5 'omp_get_dynamic' - Dynamic teams setting
=============================================

_Description_:
     This function returns 'true' if enabled, 'false' otherwise.  Here,
     'true' and 'false' represent their language-specific counterparts.

     The dynamic team setting may be initialized at startup by the
     'OMP_DYNAMIC' environment variable or at runtime using
     'omp_set_dynamic'.  If undefined, dynamic adjustment is disabled by
     default.

_C/C++_:
     _Prototype_:   'int omp_get_dynamic(void);'

_Fortran_:
     _Interface_:   'logical function omp_get_dynamic()'

_See also_:
     *note omp_set_dynamic::, *note OMP_DYNAMIC::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.8.


File: libgomp.info,  Node: omp_get_initial_device,  Next: omp_get_level,  Prev: omp_get_dynamic,  Up: Runtime Library Routines

2.6 'omp_get_initial_device' - Return device number of initial device
=====================================================================

_Description_:
     This function returns a device number that represents the host
     device.  For OpenMP 5.1, this must be equal to the value returned
     by the 'omp_get_num_devices' function.

_C/C++_
     _Prototype_:   'int omp_get_initial_device(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_initial_device()'

_See also_:
     *note omp_get_num_devices::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.35.


File: libgomp.info,  Node: omp_get_level,  Next: omp_get_max_active_levels,  Prev: omp_get_initial_device,  Up: Runtime Library Routines

2.7 'omp_get_level' - Obtain the current nesting level
======================================================

_Description_:
     This function returns the nesting level for the parallel blocks,
     which enclose the calling call.

_C/C++_
     _Prototype_:   'int omp_get_level(void);'

_Fortran_:
     _Interface_:   'integer function omp_level()'

_See also_:
     *note omp_get_active_level::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.17.


File: libgomp.info,  Node: omp_get_max_active_levels,  Next: omp_get_max_task_priority,  Prev: omp_get_level,  Up: Runtime Library Routines

2.8 'omp_get_max_active_levels' - Current maximum number of active regions
==========================================================================

_Description_:
     This function obtains the maximum allowed number of nested, active
     parallel regions.

_C/C++_
     _Prototype_:   'int omp_get_max_active_levels(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_max_active_levels()'

_See also_:
     *note omp_set_max_active_levels::, *note omp_get_active_level::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.16.


File: libgomp.info,  Node: omp_get_max_task_priority,  Next: omp_get_max_threads,  Prev: omp_get_max_active_levels,  Up: Runtime Library Routines

2.9 'omp_get_max_task_priority' - Maximum priority value
========================================================

that can be set for tasks.
_Description_:
     This function obtains the maximum allowed priority number for
     tasks.

_C/C++_
     _Prototype_:   'int omp_get_max_task_priority(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_max_task_priority()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.29.


File: libgomp.info,  Node: omp_get_max_threads,  Next: omp_get_nested,  Prev: omp_get_max_task_priority,  Up: Runtime Library Routines

2.10 'omp_get_max_threads' - Maximum number of threads of parallel region
=========================================================================

_Description_:
     Return the maximum number of threads used for the current parallel
     region that does not use the clause 'num_threads'.

_C/C++_:
     _Prototype_:   'int omp_get_max_threads(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_max_threads()'

_See also_:
     *note omp_set_num_threads::, *note omp_set_dynamic::, *note
     omp_get_thread_limit::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.3.


File: libgomp.info,  Node: omp_get_nested,  Next: omp_get_num_devices,  Prev: omp_get_max_threads,  Up: Runtime Library Routines

2.11 'omp_get_nested' - Nested parallel regions
===============================================

_Description_:
     This function returns 'true' if nested parallel regions are
     enabled, 'false' otherwise.  Here, 'true' and 'false' represent
     their language-specific counterparts.

     The state of nested parallel regions at startup depends on several
     environment variables.  If 'OMP_MAX_ACTIVE_LEVELS' is defined and
     is set to greater than one, then nested parallel regions will be
     enabled.  If not defined, then the value of the 'OMP_NESTED'
     environment variable will be followed if defined.  If neither are
     defined, then if either 'OMP_NUM_THREADS' or 'OMP_PROC_BIND' are
     defined with a list of more than one value, then nested parallel
     regions are enabled.  If none of these are defined, then nested
     parallel regions are disabled by default.

     Nested parallel regions can be enabled or disabled at runtime using
     'omp_set_nested', or by setting the maximum number of nested
     regions with 'omp_set_max_active_levels' to one to disable, or
     above one to enable.

_C/C++_:
     _Prototype_:   'int omp_get_nested(void);'

_Fortran_:
     _Interface_:   'logical function omp_get_nested()'

_See also_:
     *note omp_set_max_active_levels::, *note omp_set_nested::, *note
     OMP_MAX_ACTIVE_LEVELS::, *note OMP_NESTED::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.11.


File: libgomp.info,  Node: omp_get_num_devices,  Next: omp_get_num_procs,  Prev: omp_get_nested,  Up: Runtime Library Routines

2.12 'omp_get_num_devices' - Number of target devices
=====================================================

_Description_:
     Returns the number of target devices.

_C/C++_:
     _Prototype_:   'int omp_get_num_devices(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_num_devices()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.31.


File: libgomp.info,  Node: omp_get_num_procs,  Next: omp_get_num_teams,  Prev: omp_get_num_devices,  Up: Runtime Library Routines

2.13 'omp_get_num_procs' - Number of processors online
======================================================

_Description_:
     Returns the number of processors online on that device.

_C/C++_:
     _Prototype_:   'int omp_get_num_procs(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_num_procs()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.5.


File: libgomp.info,  Node: omp_get_num_teams,  Next: omp_get_num_threads,  Prev: omp_get_num_procs,  Up: Runtime Library Routines

2.14 'omp_get_num_teams' - Number of teams
==========================================

_Description_:
     Returns the number of teams in the current team region.

_C/C++_:
     _Prototype_:   'int omp_get_num_teams(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_num_teams()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.32.


File: libgomp.info,  Node: omp_get_num_threads,  Next: omp_get_proc_bind,  Prev: omp_get_num_teams,  Up: Runtime Library Routines

2.15 'omp_get_num_threads' - Size of the active team
====================================================

_Description_:
     Returns the number of threads in the current team.  In a sequential
     section of the program 'omp_get_num_threads' returns 1.

     The default team size may be initialized at startup by the
     'OMP_NUM_THREADS' environment variable.  At runtime, the size of
     the current team may be set either by the 'NUM_THREADS' clause or
     by 'omp_set_num_threads'.  If none of the above were used to define
     a specific value and 'OMP_DYNAMIC' is disabled, one thread per CPU
     online is used.

_C/C++_:
     _Prototype_:   'int omp_get_num_threads(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_num_threads()'

_See also_:
     *note omp_get_max_threads::, *note omp_set_num_threads::, *note
     OMP_NUM_THREADS::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.2.


File: libgomp.info,  Node: omp_get_proc_bind,  Next: omp_get_schedule,  Prev: omp_get_num_threads,  Up: Runtime Library Routines

2.16 'omp_get_proc_bind' - Whether theads may be moved between CPUs
===================================================================

_Description_:
     This functions returns the currently active thread affinity policy,
     which is set via 'OMP_PROC_BIND'.  Possible values are
     'omp_proc_bind_false', 'omp_proc_bind_true',
     'omp_proc_bind_master', 'omp_proc_bind_close' and
     'omp_proc_bind_spread'.

_C/C++_:
     _Prototype_:   'omp_proc_bind_t omp_get_proc_bind(void);'

_Fortran_:
     _Interface_:   'integer(kind=omp_proc_bind_kind) function
                    omp_get_proc_bind()'

_See also_:
     *note OMP_PROC_BIND::, *note OMP_PLACES::, *note
     GOMP_CPU_AFFINITY::,

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.22.


File: libgomp.info,  Node: omp_get_schedule,  Next: omp_get_supported_active_levels,  Prev: omp_get_proc_bind,  Up: Runtime Library Routines

2.17 'omp_get_schedule' - Obtain the runtime scheduling method
==============================================================

_Description_:
     Obtain the runtime scheduling method.  The KIND argument will be
     set to the value 'omp_sched_static', 'omp_sched_dynamic',
     'omp_sched_guided' or 'omp_sched_auto'.  The second argument,
     CHUNK_SIZE, is set to the chunk size.

_C/C++_
     _Prototype_:   'void omp_get_schedule(omp_sched_t *kind, int
                    *chunk_size);'

_Fortran_:
     _Interface_:   'subroutine omp_get_schedule(kind, chunk_size)'
                    'integer(kind=omp_sched_kind) kind'
                    'integer chunk_size'

_See also_:
     *note omp_set_schedule::, *note OMP_SCHEDULE::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.13.


File: libgomp.info,  Node: omp_get_supported_active_levels,  Next: omp_get_team_num,  Prev: omp_get_schedule,  Up: Runtime Library Routines

2.18 'omp_get_supported_active_levels' - Maximum number of active regions supported
===================================================================================

_Description_:
     This function returns the maximum number of nested, active parallel
     regions supported by this implementation.

_C/C++_
     _Prototype_:   'int omp_get_supported_active_levels(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_supported_active_levels()'

_See also_:
     *note omp_get_max_active_levels::, *note
     omp_set_max_active_levels::

_Reference_:
     OpenMP specification v5.0 (https://www.openmp.org), Section 3.2.15.


File: libgomp.info,  Node: omp_get_team_num,  Next: omp_get_team_size,  Prev: omp_get_supported_active_levels,  Up: Runtime Library Routines

2.19 'omp_get_team_num' - Get team number
=========================================

_Description_:
     Returns the team number of the calling thread.

_C/C++_:
     _Prototype_:   'int omp_get_team_num(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_team_num()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.33.


File: libgomp.info,  Node: omp_get_team_size,  Next: omp_get_thread_limit,  Prev: omp_get_team_num,  Up: Runtime Library Routines

2.20 'omp_get_team_size' - Number of threads in a team
======================================================

_Description_:
     This function returns the number of threads in a thread team to
     which either the current thread or its ancestor belongs.  For
     values of LEVEL outside zero to 'omp_get_level', -1 is returned; if
     LEVEL is zero, 1 is returned, and for 'omp_get_level', the result
     is identical to 'omp_get_num_threads'.

_C/C++_:
     _Prototype_:   'int omp_get_team_size(int level);'

_Fortran_:
     _Interface_:   'integer function omp_get_team_size(level)'
                    'integer level'

_See also_:
     *note omp_get_num_threads::, *note omp_get_level::, *note
     omp_get_ancestor_thread_num::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.19.


File: libgomp.info,  Node: omp_get_thread_limit,  Next: omp_get_thread_num,  Prev: omp_get_team_size,  Up: Runtime Library Routines

2.21 'omp_get_thread_limit' - Maximum number of threads
=======================================================

_Description_:
     Return the maximum number of threads of the program.

_C/C++_:
     _Prototype_:   'int omp_get_thread_limit(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_thread_limit()'

_See also_:
     *note omp_get_max_threads::, *note OMP_THREAD_LIMIT::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.14.


File: libgomp.info,  Node: omp_get_thread_num,  Next: omp_in_parallel,  Prev: omp_get_thread_limit,  Up: Runtime Library Routines

2.22 'omp_get_thread_num' - Current thread ID
=============================================

_Description_:
     Returns a unique thread identification number within the current
     team.  In a sequential parts of the program, 'omp_get_thread_num'
     always returns 0.  In parallel regions the return value varies from
     0 to 'omp_get_num_threads'-1 inclusive.  The return value of the
     master thread of a team is always 0.

_C/C++_:
     _Prototype_:   'int omp_get_thread_num(void);'

_Fortran_:
     _Interface_:   'integer function omp_get_thread_num()'

_See also_:
     *note omp_get_num_threads::, *note omp_get_ancestor_thread_num::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.4.


File: libgomp.info,  Node: omp_in_parallel,  Next: omp_in_final,  Prev: omp_get_thread_num,  Up: Runtime Library Routines

2.23 'omp_in_parallel' - Whether a parallel region is active
============================================================

_Description_:
     This function returns 'true' if currently running in parallel,
     'false' otherwise.  Here, 'true' and 'false' represent their
     language-specific counterparts.

_C/C++_:
     _Prototype_:   'int omp_in_parallel(void);'

_Fortran_:
     _Interface_:   'logical function omp_in_parallel()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.6.


File: libgomp.info,  Node: omp_in_final,  Next: omp_is_initial_device,  Prev: omp_in_parallel,  Up: Runtime Library Routines

2.24 'omp_in_final' - Whether in final or included task region
==============================================================

_Description_:
     This function returns 'true' if currently running in a final or
     included task region, 'false' otherwise.  Here, 'true' and 'false'
     represent their language-specific counterparts.

_C/C++_:
     _Prototype_:   'int omp_in_final(void);'

_Fortran_:
     _Interface_:   'logical function omp_in_final()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.21.


File: libgomp.info,  Node: omp_is_initial_device,  Next: omp_set_default_device,  Prev: omp_in_final,  Up: Runtime Library Routines

2.25 'omp_is_initial_device' - Whether executing on the host device
===================================================================

_Description_:
     This function returns 'true' if currently running on the host
     device, 'false' otherwise.  Here, 'true' and 'false' represent
     their language-specific counterparts.

_C/C++_:
     _Prototype_:   'int omp_is_initial_device(void);'

_Fortran_:
     _Interface_:   'logical function omp_is_initial_device()'

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.34.


File: libgomp.info,  Node: omp_set_default_device,  Next: omp_set_dynamic,  Prev: omp_is_initial_device,  Up: Runtime Library Routines

2.26 'omp_set_default_device' - Set the default device for target regions
=========================================================================

_Description_:
     Set the default device for target regions without device clause.
     The argument shall be a nonnegative device number.

_C/C++_:
     _Prototype_:   'void omp_set_default_device(int device_num);'

_Fortran_:
     _Interface_:   'subroutine omp_set_default_device(device_num)'
                    'integer device_num'

_See also_:
     *note OMP_DEFAULT_DEVICE::, *note omp_get_default_device::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.29.


File: libgomp.info,  Node: omp_set_dynamic,  Next: omp_set_max_active_levels,  Prev: omp_set_default_device,  Up: Runtime Library Routines

2.27 'omp_set_dynamic' - Enable/disable dynamic teams
=====================================================

_Description_:
     Enable or disable the dynamic adjustment of the number of threads
     within a team.  The function takes the language-specific equivalent
     of 'true' and 'false', where 'true' enables dynamic adjustment of
     team sizes and 'false' disables it.

_C/C++_:
     _Prototype_:   'void omp_set_dynamic(int dynamic_threads);'

_Fortran_:
     _Interface_:   'subroutine omp_set_dynamic(dynamic_threads)'
                    'logical, intent(in) :: dynamic_threads'

_See also_:
     *note OMP_DYNAMIC::, *note omp_get_dynamic::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.7.


File: libgomp.info,  Node: omp_set_max_active_levels,  Next: omp_set_nested,  Prev: omp_set_dynamic,  Up: Runtime Library Routines

2.28 'omp_set_max_active_levels' - Limits the number of active parallel regions
===============================================================================

_Description_:
     This function limits the maximum allowed number of nested, active
     parallel regions.  MAX_LEVELS must be less or equal to the value
     returned by 'omp_get_supported_active_levels'.

_C/C++_
     _Prototype_:   'void omp_set_max_active_levels(int max_levels);'

_Fortran_:
     _Interface_:   'subroutine omp_set_max_active_levels(max_levels)'
                    'integer max_levels'

_See also_:
     *note omp_get_max_active_levels::, *note omp_get_active_level::,
     *note omp_get_supported_active_levels::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.15.


File: libgomp.info,  Node: omp_set_nested,  Next: omp_set_num_threads,  Prev: omp_set_max_active_levels,  Up: Runtime Library Routines

2.29 'omp_set_nested' - Enable/disable nested parallel regions
==============================================================

_Description_:
     Enable or disable nested parallel regions, i.e., whether team
     members are allowed to create new teams.  The function takes the
     language-specific equivalent of 'true' and 'false', where 'true'
     enables dynamic adjustment of team sizes and 'false' disables it.

     Enabling nested parallel regions will also set the maximum number
     of active nested regions to the maximum supported.  Disabling
     nested parallel regions will set the maximum number of active
     nested regions to one.

_C/C++_:
     _Prototype_:   'void omp_set_nested(int nested);'

_Fortran_:
     _Interface_:   'subroutine omp_set_nested(nested)'
                    'logical, intent(in) :: nested'

_See also_:
     *note omp_get_nested::, *note omp_set_max_active_levels::, *note
     OMP_MAX_ACTIVE_LEVELS::, *note OMP_NESTED::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.10.


File: libgomp.info,  Node: omp_set_num_threads,  Next: omp_set_schedule,  Prev: omp_set_nested,  Up: Runtime Library Routines

2.30 'omp_set_num_threads' - Set upper team size limit
======================================================

_Description_:
     Specifies the number of threads used by default in subsequent
     parallel sections, if those do not specify a 'num_threads' clause.
     The argument of 'omp_set_num_threads' shall be a positive integer.

_C/C++_:
     _Prototype_:   'void omp_set_num_threads(int num_threads);'

_Fortran_:
     _Interface_:   'subroutine omp_set_num_threads(num_threads)'
                    'integer, intent(in) :: num_threads'

_See also_:
     *note OMP_NUM_THREADS::, *note omp_get_num_threads::, *note
     omp_get_max_threads::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.1.


File: libgomp.info,  Node: omp_set_schedule,  Next: omp_init_lock,  Prev: omp_set_num_threads,  Up: Runtime Library Routines

2.31 'omp_set_schedule' - Set the runtime scheduling method
===========================================================

_Description_:
     Sets the runtime scheduling method.  The KIND argument can have the
     value 'omp_sched_static', 'omp_sched_dynamic', 'omp_sched_guided'
     or 'omp_sched_auto'.  Except for 'omp_sched_auto', the chunk size
     is set to the value of CHUNK_SIZE if positive, or to the default
     value if zero or negative.  For 'omp_sched_auto' the CHUNK_SIZE
     argument is ignored.

_C/C++_
     _Prototype_:   'void omp_set_schedule(omp_sched_t kind, int
                    chunk_size);'

_Fortran_:
     _Interface_:   'subroutine omp_set_schedule(kind, chunk_size)'
                    'integer(kind=omp_sched_kind) kind'
                    'integer chunk_size'

_See also_:
     *note omp_get_schedule:: *note OMP_SCHEDULE::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.2.12.


File: libgomp.info,  Node: omp_init_lock,  Next: omp_set_lock,  Prev: omp_set_schedule,  Up: Runtime Library Routines

2.32 'omp_init_lock' - Initialize simple lock
=============================================

_Description_:
     Initialize a simple lock.  After initialization, the lock is in an
     unlocked state.

_C/C++_:
     _Prototype_:   'void omp_init_lock(omp_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_init_lock(svar)'
                    'integer(omp_lock_kind), intent(out) :: svar'

_See also_:
     *note omp_destroy_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.1.


File: libgomp.info,  Node: omp_set_lock,  Next: omp_test_lock,  Prev: omp_init_lock,  Up: Runtime Library Routines

2.33 'omp_set_lock' - Wait for and set simple lock
==================================================

_Description_:
     Before setting a simple lock, the lock variable must be initialized
     by 'omp_init_lock'.  The calling thread is blocked until the lock
     is available.  If the lock is already held by the current thread, a
     deadlock occurs.

_C/C++_:
     _Prototype_:   'void omp_set_lock(omp_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_set_lock(svar)'
                    'integer(omp_lock_kind), intent(inout) :: svar'

_See also_:
     *note omp_init_lock::, *note omp_test_lock::, *note
     omp_unset_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.4.


File: libgomp.info,  Node: omp_test_lock,  Next: omp_unset_lock,  Prev: omp_set_lock,  Up: Runtime Library Routines

2.34 'omp_test_lock' - Test and set simple lock if available
============================================================

_Description_:
     Before setting a simple lock, the lock variable must be initialized
     by 'omp_init_lock'.  Contrary to 'omp_set_lock', 'omp_test_lock'
     does not block if the lock is not available.  This function returns
     'true' upon success, 'false' otherwise.  Here, 'true' and 'false'
     represent their language-specific counterparts.

_C/C++_:
     _Prototype_:   'int omp_test_lock(omp_lock_t *lock);'

_Fortran_:
     _Interface_:   'logical function omp_test_lock(svar)'
                    'integer(omp_lock_kind), intent(inout) :: svar'

_See also_:
     *note omp_init_lock::, *note omp_set_lock::, *note omp_set_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.6.


File: libgomp.info,  Node: omp_unset_lock,  Next: omp_destroy_lock,  Prev: omp_test_lock,  Up: Runtime Library Routines

2.35 'omp_unset_lock' - Unset simple lock
=========================================

_Description_:
     A simple lock about to be unset must have been locked by
     'omp_set_lock' or 'omp_test_lock' before.  In addition, the lock
     must be held by the thread calling 'omp_unset_lock'.  Then, the
     lock becomes unlocked.  If one or more threads attempted to set the
     lock before, one of them is chosen to, again, set the lock to
     itself.

_C/C++_:
     _Prototype_:   'void omp_unset_lock(omp_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_unset_lock(svar)'
                    'integer(omp_lock_kind), intent(inout) :: svar'

_See also_:
     *note omp_set_lock::, *note omp_test_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.5.


File: libgomp.info,  Node: omp_destroy_lock,  Next: omp_init_nest_lock,  Prev: omp_unset_lock,  Up: Runtime Library Routines

2.36 'omp_destroy_lock' - Destroy simple lock
=============================================

_Description_:
     Destroy a simple lock.  In order to be destroyed, a simple lock
     must be in the unlocked state.

_C/C++_:
     _Prototype_:   'void omp_destroy_lock(omp_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_destroy_lock(svar)'
                    'integer(omp_lock_kind), intent(inout) :: svar'

_See also_:
     *note omp_init_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.3.


File: libgomp.info,  Node: omp_init_nest_lock,  Next: omp_set_nest_lock,  Prev: omp_destroy_lock,  Up: Runtime Library Routines

2.37 'omp_init_nest_lock' - Initialize nested lock
==================================================

_Description_:
     Initialize a nested lock.  After initialization, the lock is in an
     unlocked state and the nesting count is set to zero.

_C/C++_:
     _Prototype_:   'void omp_init_nest_lock(omp_nest_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_init_nest_lock(nvar)'
                    'integer(omp_nest_lock_kind), intent(out) :: nvar'

_See also_:
     *note omp_destroy_nest_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.1.


File: libgomp.info,  Node: omp_set_nest_lock,  Next: omp_test_nest_lock,  Prev: omp_init_nest_lock,  Up: Runtime Library Routines

2.38 'omp_set_nest_lock' - Wait for and set nested lock
=======================================================

_Description_:
     Before setting a nested lock, the lock variable must be initialized
     by 'omp_init_nest_lock'.  The calling thread is blocked until the
     lock is available.  If the lock is already held by the current
     thread, the nesting count for the lock is incremented.

_C/C++_:
     _Prototype_:   'void omp_set_nest_lock(omp_nest_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_set_nest_lock(nvar)'
                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'

_See also_:
     *note omp_init_nest_lock::, *note omp_unset_nest_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.4.


File: libgomp.info,  Node: omp_test_nest_lock,  Next: omp_unset_nest_lock,  Prev: omp_set_nest_lock,  Up: Runtime Library Routines

2.39 'omp_test_nest_lock' - Test and set nested lock if available
=================================================================

_Description_:
     Before setting a nested lock, the lock variable must be initialized
     by 'omp_init_nest_lock'.  Contrary to 'omp_set_nest_lock',
     'omp_test_nest_lock' does not block if the lock is not available.
     If the lock is already held by the current thread, the new nesting
     count is returned.  Otherwise, the return value equals zero.

_C/C++_:
     _Prototype_:   'int omp_test_nest_lock(omp_nest_lock_t *lock);'

_Fortran_:
     _Interface_:   'logical function omp_test_nest_lock(nvar)'
                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'

_See also_:
     *note omp_init_lock::, *note omp_set_lock::, *note omp_set_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.6.


File: libgomp.info,  Node: omp_unset_nest_lock,  Next: omp_destroy_nest_lock,  Prev: omp_test_nest_lock,  Up: Runtime Library Routines

2.40 'omp_unset_nest_lock' - Unset nested lock
==============================================

_Description_:
     A nested lock about to be unset must have been locked by
     'omp_set_nested_lock' or 'omp_test_nested_lock' before.  In
     addition, the lock must be held by the thread calling
     'omp_unset_nested_lock'.  If the nesting count drops to zero, the
     lock becomes unlocked.  If one ore more threads attempted to set
     the lock before, one of them is chosen to, again, set the lock to
     itself.

_C/C++_:
     _Prototype_:   'void omp_unset_nest_lock(omp_nest_lock_t *lock);'

_Fortran_:
     _Interface_:   'subroutine omp_unset_nest_lock(nvar)'
                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'

_See also_:
     *note omp_set_nest_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.5.


File: libgomp.info,  Node: omp_destroy_nest_lock,  Next: omp_get_wtick,  Prev: omp_unset_nest_lock,  Up: Runtime Library Routines

2.41 'omp_destroy_nest_lock' - Destroy nested lock
==================================================

_Description_:
     Destroy a nested lock.  In order to be destroyed, a nested lock
     must be in the unlocked state and its nesting count must equal
     zero.

_C/C++_:
     _Prototype_:   'void omp_destroy_nest_lock(omp_nest_lock_t *);'

_Fortran_:
     _Interface_:   'subroutine omp_destroy_nest_lock(nvar)'
                    'integer(omp_nest_lock_kind), intent(inout) :: nvar'

_See also_:
     *note omp_init_lock::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.3.3.


File: libgomp.info,  Node: omp_get_wtick,  Next: omp_get_wtime,  Prev: omp_destroy_nest_lock,  Up: Runtime Library Routines

2.42 'omp_get_wtick' - Get timer precision
==========================================

_Description_:
     Gets the timer precision, i.e., the number of seconds between two
     successive clock ticks.

_C/C++_:
     _Prototype_:   'double omp_get_wtick(void);'

_Fortran_:
     _Interface_:   'double precision function omp_get_wtick()'

_See also_:
     *note omp_get_wtime::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.4.2.


File: libgomp.info,  Node: omp_get_wtime,  Next: omp_fulfill_event,  Prev: omp_get_wtick,  Up: Runtime Library Routines

2.43 'omp_get_wtime' - Elapsed wall clock time
==============================================

_Description_:
     Elapsed wall clock time in seconds.  The time is measured per
     thread, no guarantee can be made that two distinct threads measure
     the same time.  Time is measured from some "time in the past",
     which is an arbitrary time guaranteed not to change during the
     execution of the program.

_C/C++_:
     _Prototype_:   'double omp_get_wtime(void);'

_Fortran_:
     _Interface_:   'double precision function omp_get_wtime()'

_See also_:
     *note omp_get_wtick::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 3.4.1.


File: libgomp.info,  Node: omp_fulfill_event,  Prev: omp_get_wtime,  Up: Runtime Library Routines

2.44 'omp_fulfill_event' - Fulfill and destroy an OpenMP event
==============================================================

_Description_:
     Fulfill the event associated with the event handle argument.
     Currently, it is only used to fulfill events generated by detach
     clauses on task constructs - the effect of fulfilling the event is
     to allow the task to complete.

     The result of calling 'omp_fulfill_event' with an event handle
     other than that generated by a detach clause is undefined.  Calling
     it with an event handle that has already been fulfilled is also
     undefined.

_C/C++_:
     _Prototype_:   'void omp_fulfill_event(omp_event_handle_t event);'

_Fortran_:
     _Interface_:   'subroutine omp_fulfill_event(event)'
                    'integer (kind=omp_event_handle_kind) :: event'

_Reference_:
     OpenMP specification v5.0 (https://www.openmp.org), Section 3.5.1.


File: libgomp.info,  Node: Environment Variables,  Next: Enabling OpenACC,  Prev: Runtime Library Routines,  Up: Top

3 OpenMP Environment Variables
******************************

The environment variables which beginning with 'OMP_' are defined by
section 4 of the OpenMP specification in version 4.5, while those
beginning with 'GOMP_' are GNU extensions.

* Menu:

* OMP_CANCELLATION::        Set whether cancellation is activated
* OMP_DISPLAY_ENV::         Show OpenMP version and environment variables
* OMP_DEFAULT_DEVICE::      Set the device used in target regions
* OMP_DYNAMIC::             Dynamic adjustment of threads
* OMP_MAX_ACTIVE_LEVELS::   Set the maximum number of nested parallel regions
* OMP_MAX_TASK_PRIORITY::   Set the maximum task priority value
* OMP_NESTED::              Nested parallel regions
* OMP_NUM_THREADS::         Specifies the number of threads to use
* OMP_PROC_BIND::           Whether theads may be moved between CPUs
* OMP_PLACES::              Specifies on which CPUs the theads should be placed
* OMP_STACKSIZE::           Set default thread stack size
* OMP_SCHEDULE::            How threads are scheduled
* OMP_TARGET_OFFLOAD::      Controls offloading behaviour
* OMP_THREAD_LIMIT::        Set the maximum number of threads
* OMP_WAIT_POLICY::         How waiting threads are handled
* GOMP_CPU_AFFINITY::       Bind threads to specific CPUs
* GOMP_DEBUG::              Enable debugging output
* GOMP_STACKSIZE::          Set default thread stack size
* GOMP_SPINCOUNT::          Set the busy-wait spin count
* GOMP_RTEMS_THREAD_POOLS:: Set the RTEMS specific thread pools


File: libgomp.info,  Node: OMP_CANCELLATION,  Next: OMP_DISPLAY_ENV,  Up: Environment Variables

3.1 'OMP_CANCELLATION' - Set whether cancellation is activated
==============================================================

_Description_:
     If set to 'TRUE', the cancellation is activated.  If set to 'FALSE'
     or if unset, cancellation is disabled and the 'cancel' construct is
     ignored.

_See also_:
     *note omp_get_cancellation::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.11


File: libgomp.info,  Node: OMP_DISPLAY_ENV,  Next: OMP_DEFAULT_DEVICE,  Prev: OMP_CANCELLATION,  Up: Environment Variables

3.2 'OMP_DISPLAY_ENV' - Show OpenMP version and environment variables
=====================================================================

_Description_:
     If set to 'TRUE', the OpenMP version number and the values
     associated with the OpenMP environment variables are printed to
     'stderr'.  If set to 'VERBOSE', it additionally shows the value of
     the environment variables which are GNU extensions.  If undefined
     or set to 'FALSE', this information will not be shown.

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.12


File: libgomp.info,  Node: OMP_DEFAULT_DEVICE,  Next: OMP_DYNAMIC,  Prev: OMP_DISPLAY_ENV,  Up: Environment Variables

3.3 'OMP_DEFAULT_DEVICE' - Set the device used in target regions
================================================================

_Description_:
     Set to choose the device which is used in a 'target' region, unless
     the value is overridden by 'omp_set_default_device' or by a
     'device' clause.  The value shall be the nonnegative device number.
     If no device with the given device number exists, the code is
     executed on the host.  If unset, device number 0 will be used.

_See also_:
     *note omp_get_default_device::, *note omp_set_default_device::,

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.13


File: libgomp.info,  Node: OMP_DYNAMIC,  Next: OMP_MAX_ACTIVE_LEVELS,  Prev: OMP_DEFAULT_DEVICE,  Up: Environment Variables

3.4 'OMP_DYNAMIC' - Dynamic adjustment of threads
=================================================

_Description_:
     Enable or disable the dynamic adjustment of the number of threads
     within a team.  The value of this environment variable shall be
     'TRUE' or 'FALSE'.  If undefined, dynamic adjustment is disabled by
     default.

_See also_:
     *note omp_set_dynamic::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.3


File: libgomp.info,  Node: OMP_MAX_ACTIVE_LEVELS,  Next: OMP_MAX_TASK_PRIORITY,  Prev: OMP_DYNAMIC,  Up: Environment Variables

3.5 'OMP_MAX_ACTIVE_LEVELS' - Set the maximum number of nested parallel regions
===============================================================================

_Description_:
     Specifies the initial value for the maximum number of nested
     parallel regions.  The value of this variable shall be a positive
     integer.  If undefined, then if 'OMP_NESTED' is defined and set to
     true, or if 'OMP_NUM_THREADS' or 'OMP_PROC_BIND' are defined and
     set to a list with more than one item, the maximum number of nested
     parallel regions will be initialized to the largest number
     supported, otherwise it will be set to one.

_See also_:
     *note omp_set_max_active_levels::, *note OMP_NESTED::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.9


File: libgomp.info,  Node: OMP_MAX_TASK_PRIORITY,  Next: OMP_NESTED,  Prev: OMP_MAX_ACTIVE_LEVELS,  Up: Environment Variables

3.6 'OMP_MAX_TASK_PRIORITY' - Set the maximum priority
======================================================

number that can be set for a task.
_Description_:
     Specifies the initial value for the maximum priority value that can
     be set for a task.  The value of this variable shall be a
     non-negative integer, and zero is allowed.  If undefined, the
     default priority is 0.

_See also_:
     *note omp_get_max_task_priority::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.14


File: libgomp.info,  Node: OMP_NESTED,  Next: OMP_NUM_THREADS,  Prev: OMP_MAX_TASK_PRIORITY,  Up: Environment Variables

3.7 'OMP_NESTED' - Nested parallel regions
==========================================

_Description_:
     Enable or disable nested parallel regions, i.e., whether team
     members are allowed to create new teams.  The value of this
     environment variable shall be 'TRUE' or 'FALSE'.  If set to 'TRUE',
     the number of maximum active nested regions supported will by
     default be set to the maximum supported, otherwise it will be set
     to one.  If 'OMP_MAX_ACTIVE_LEVELS' is defined, its setting will
     override this setting.  If both are undefined, nested parallel
     regions are enabled if 'OMP_NUM_THREADS' or 'OMP_PROC_BINDS' are
     defined to a list with more than one item, otherwise they are
     disabled by default.

_See also_:
     *note omp_set_max_active_levels::, *note omp_set_nested::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.6


File: libgomp.info,  Node: OMP_NUM_THREADS,  Next: OMP_PROC_BIND,  Prev: OMP_NESTED,  Up: Environment Variables

3.8 'OMP_NUM_THREADS' - Specifies the number of threads to use
==============================================================

_Description_:
     Specifies the default number of threads to use in parallel regions.
     The value of this variable shall be a comma-separated list of
     positive integers; the value specifies the number of threads to use
     for the corresponding nested level.  Specifying more than one item
     in the list will automatically enable nesting by default.  If
     undefined one thread per CPU is used.

_See also_:
     *note omp_set_num_threads::, *note OMP_NESTED::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.2


File: libgomp.info,  Node: OMP_PROC_BIND,  Next: OMP_PLACES,  Prev: OMP_NUM_THREADS,  Up: Environment Variables

3.9 'OMP_PROC_BIND' - Whether theads may be moved between CPUs
==============================================================

_Description_:
     Specifies whether threads may be moved between processors.  If set
     to 'TRUE', OpenMP theads should not be moved; if set to 'FALSE'
     they may be moved.  Alternatively, a comma separated list with the
     values 'MASTER', 'CLOSE' and 'SPREAD' can be used to specify the
     thread affinity policy for the corresponding nesting level.  With
     'MASTER' the worker threads are in the same place partition as the
     master thread.  With 'CLOSE' those are kept close to the master
     thread in contiguous place partitions.  And with 'SPREAD' a sparse
     distribution across the place partitions is used.  Specifying more
     than one item in the list will automatically enable nesting by
     default.

     When undefined, 'OMP_PROC_BIND' defaults to 'TRUE' when
     'OMP_PLACES' or 'GOMP_CPU_AFFINITY' is set and 'FALSE' otherwise.

_See also_:
     *note omp_get_proc_bind::, *note GOMP_CPU_AFFINITY::, *note
     OMP_NESTED::, *note OMP_PLACES::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.4


File: libgomp.info,  Node: OMP_PLACES,  Next: OMP_STACKSIZE,  Prev: OMP_PROC_BIND,  Up: Environment Variables

3.10 'OMP_PLACES' - Specifies on which CPUs the theads should be placed
=======================================================================

_Description_:
     The thread placement can be either specified using an abstract name
     or by an explicit list of the places.  The abstract names
     'threads', 'cores' and 'sockets' can be optionally followed by a
     positive number in parentheses, which denotes the how many places
     shall be created.  With 'threads' each place corresponds to a
     single hardware thread; 'cores' to a single core with the
     corresponding number of hardware threads; and with 'sockets' the
     place corresponds to a single socket.  The resulting placement can
     be shown by setting the 'OMP_DISPLAY_ENV' environment variable.

     Alternatively, the placement can be specified explicitly as
     comma-separated list of places.  A place is specified by set of
     nonnegative numbers in curly braces, denoting the denoting the
     hardware threads.  The hardware threads belonging to a place can
     either be specified as comma-separated list of nonnegative thread
     numbers or using an interval.  Multiple places can also be either
     specified by a comma-separated list of places or by an interval.
     To specify an interval, a colon followed by the count is placed
     after after the hardware thread number or the place.  Optionally,
     the length can be followed by a colon and the stride number -
     otherwise a unit stride is assumed.  For instance, the following
     specifies the same places list: '"{0,1,2}, {3,4,6}, {7,8,9},
     {10,11,12}"'; '"{0:3}, {3:3}, {7:3}, {10:3}"'; and '"{0:2}:4:3"'.

     If 'OMP_PLACES' and 'GOMP_CPU_AFFINITY' are unset and
     'OMP_PROC_BIND' is either unset or 'false', threads may be moved
     between CPUs following no placement policy.

_See also_:
     *note OMP_PROC_BIND::, *note GOMP_CPU_AFFINITY::, *note
     omp_get_proc_bind::, *note OMP_DISPLAY_ENV::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.5


File: libgomp.info,  Node: OMP_STACKSIZE,  Next: OMP_SCHEDULE,  Prev: OMP_PLACES,  Up: Environment Variables

3.11 'OMP_STACKSIZE' - Set default thread stack size
====================================================

_Description_:
     Set the default thread stack size in kilobytes, unless the number
     is suffixed by 'B', 'K', 'M' or 'G', in which case the size is,
     respectively, in bytes, kilobytes, megabytes or gigabytes.  This is
     different from 'pthread_attr_setstacksize' which gets the number of
     bytes as an argument.  If the stack size cannot be set due to
     system constraints, an error is reported and the initial stack size
     is left unchanged.  If undefined, the stack size is system
     dependent.

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.7


File: libgomp.info,  Node: OMP_SCHEDULE,  Next: OMP_TARGET_OFFLOAD,  Prev: OMP_STACKSIZE,  Up: Environment Variables

3.12 'OMP_SCHEDULE' - How threads are scheduled
===============================================

_Description_:
     Allows to specify 'schedule type' and 'chunk size'.  The value of
     the variable shall have the form: 'type[,chunk]' where 'type' is
     one of 'static', 'dynamic', 'guided' or 'auto' The optional 'chunk'
     size shall be a positive integer.  If undefined, dynamic scheduling
     and a chunk size of 1 is used.

_See also_:
     *note omp_set_schedule::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Sections
     2.7.1.1 and 4.1


File: libgomp.info,  Node: OMP_TARGET_OFFLOAD,  Next: OMP_THREAD_LIMIT,  Prev: OMP_SCHEDULE,  Up: Environment Variables

3.13 'OMP_TARGET_OFFLOAD' - Controls offloading behaviour
=========================================================

_Description_:
     Specifies the behaviour with regard to offloading code to a device.
     This variable can be set to one of three values - 'MANDATORY',
     'DISABLED' or 'DEFAULT'.

     If set to 'MANDATORY', the program will terminate with an error if
     the offload device is not present or is not supported.  If set to
     'DISABLED', then offloading is disabled and all code will run on
     the host.  If set to 'DEFAULT', the program will try offloading to
     the device first, then fall back to running code on the host if it
     cannot.

     If undefined, then the program will behave as if 'DEFAULT' was set.

_Reference_:
     OpenMP specification v5.0 (https://www.openmp.org), Section 6.17


File: libgomp.info,  Node: OMP_THREAD_LIMIT,  Next: OMP_WAIT_POLICY,  Prev: OMP_TARGET_OFFLOAD,  Up: Environment Variables

3.14 'OMP_THREAD_LIMIT' - Set the maximum number of threads
===========================================================

_Description_:
     Specifies the number of threads to use for the whole program.  The
     value of this variable shall be a positive integer.  If undefined,
     the number of threads is not limited.

_See also_:
     *note OMP_NUM_THREADS::, *note omp_get_thread_limit::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.10


File: libgomp.info,  Node: OMP_WAIT_POLICY,  Next: GOMP_CPU_AFFINITY,  Prev: OMP_THREAD_LIMIT,  Up: Environment Variables

3.15 'OMP_WAIT_POLICY' - How waiting threads are handled
========================================================

_Description_:
     Specifies whether waiting threads should be active or passive.  If
     the value is 'PASSIVE', waiting threads should not consume CPU
     power while waiting; while the value is 'ACTIVE' specifies that
     they should.  If undefined, threads wait actively for a short time
     before waiting passively.

_See also_:
     *note GOMP_SPINCOUNT::

_Reference_:
     OpenMP specification v4.5 (https://www.openmp.org), Section 4.8


File: libgomp.info,  Node: GOMP_CPU_AFFINITY,  Next: GOMP_DEBUG,  Prev: OMP_WAIT_POLICY,  Up: Environment Variables

3.16 'GOMP_CPU_AFFINITY' - Bind threads to specific CPUs
========================================================

_Description_:
     Binds threads to specific CPUs.  The variable should contain a
     space-separated or comma-separated list of CPUs.  This list may
     contain different kinds of entries: either single CPU numbers in
     any order, a range of CPUs (M-N) or a range with some stride
     (M-N:S). CPU numbers are zero based.  For example,
     'GOMP_CPU_AFFINITY="0 3 1-2 4-15:2"' will bind the initial thread
     to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to
     CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8,
     10, 12, and 14 respectively and then start assigning back from the
     beginning of the list.  'GOMP_CPU_AFFINITY=0' binds all threads to
     CPU 0.

     There is no libgomp library routine to determine whether a CPU
     affinity specification is in effect.  As a workaround,
     language-specific library functions, e.g., 'getenv' in C or
     'GET_ENVIRONMENT_VARIABLE' in Fortran, may be used to query the
     setting of the 'GOMP_CPU_AFFINITY' environment variable.  A defined
     CPU affinity on startup cannot be changed or disabled during the
     runtime of the application.

     If both 'GOMP_CPU_AFFINITY' and 'OMP_PROC_BIND' are set,
     'OMP_PROC_BIND' has a higher precedence.  If neither has been set
     and 'OMP_PROC_BIND' is unset, or when 'OMP_PROC_BIND' is set to
     'FALSE', the host system will handle the assignment of threads to
     CPUs.

_See also_:
     *note OMP_PLACES::, *note OMP_PROC_BIND::


File: libgomp.info,  Node: GOMP_DEBUG,  Next: GOMP_STACKSIZE,  Prev: GOMP_CPU_AFFINITY,  Up: Environment Variables

3.17 'GOMP_DEBUG' - Enable debugging output
===========================================

_Description_:
     Enable debugging output.  The variable should be set to '0'
     (disabled, also the default if not set), or '1' (enabled).

     If enabled, some debugging output will be printed during execution.
     This is currently not specified in more detail, and subject to
     change.


File: libgomp.info,  Node: GOMP_STACKSIZE,  Next: GOMP_SPINCOUNT,  Prev: GOMP_DEBUG,  Up: Environment Variables

3.18 'GOMP_STACKSIZE' - Set default thread stack size
=====================================================

_Description_:
     Set the default thread stack size in kilobytes.  This is different
     from 'pthread_attr_setstacksize' which gets the number of bytes as
     an argument.  If the stack size cannot be set due to system
     constraints, an error is reported and the initial stack size is
     left unchanged.  If undefined, the stack size is system dependent.

_See also_:
     *note OMP_STACKSIZE::

_Reference_:
     GCC Patches Mailinglist
     (https://gcc.gnu.org/ml/gcc-patches/2006-06/msg00493.html), GCC
     Patches Mailinglist
     (https://gcc.gnu.org/ml/gcc-patches/2006-06/msg00496.html)


File: libgomp.info,  Node: GOMP_SPINCOUNT,  Next: GOMP_RTEMS_THREAD_POOLS,  Prev: GOMP_STACKSIZE,  Up: Environment Variables

3.19 'GOMP_SPINCOUNT' - Set the busy-wait spin count
====================================================

_Description_:
     Determines how long a threads waits actively with consuming CPU
     power before waiting passively without consuming CPU power.  The
     value may be either 'INFINITE', 'INFINITY' to always wait actively
     or an integer which gives the number of spins of the busy-wait
     loop.  The integer may optionally be followed by the following
     suffixes acting as multiplication factors: 'k' (kilo, thousand),
     'M' (mega, million), 'G' (giga, billion), or 'T' (tera, trillion).
     If undefined, 0 is used when 'OMP_WAIT_POLICY' is 'PASSIVE',
     300,000 is used when 'OMP_WAIT_POLICY' is undefined and 30 billion
     is used when 'OMP_WAIT_POLICY' is 'ACTIVE'.  If there are more
     OpenMP threads than available CPUs, 1000 and 100 spins are used for
     'OMP_WAIT_POLICY' being 'ACTIVE' or undefined, respectively; unless
     the 'GOMP_SPINCOUNT' is lower or 'OMP_WAIT_POLICY' is 'PASSIVE'.

_See also_:
     *note OMP_WAIT_POLICY::


File: libgomp.info,  Node: GOMP_RTEMS_THREAD_POOLS,  Prev: GOMP_SPINCOUNT,  Up: Environment Variables

3.20 'GOMP_RTEMS_THREAD_POOLS' - Set the RTEMS specific thread pools
====================================================================

_Description_:
     This environment variable is only used on the RTEMS real-time
     operating system.  It determines the scheduler instance specific
     thread pools.  The format for 'GOMP_RTEMS_THREAD_POOLS' is a list
     of optional '<thread-pool-count>[$<priority>]@<scheduler-name>'
     configurations separated by ':' where:
        * '<thread-pool-count>' is the thread pool count for this
          scheduler instance.
        * '$<priority>' is an optional priority for the worker threads
          of a thread pool according to 'pthread_setschedparam'.  In
          case a priority value is omitted, then a worker thread will
          inherit the priority of the OpenMP master thread that created
          it.  The priority of the worker thread is not changed after
          creation, even if a new OpenMP master thread using the worker
          has a different priority.
        * '@<scheduler-name>' is the scheduler instance name according
          to the RTEMS application configuration.
     In case no thread pool configuration is specified for a scheduler
     instance, then each OpenMP master thread of this scheduler instance
     will use its own dynamically allocated thread pool.  To limit the
     worker thread count of the thread pools, each OpenMP master thread
     must call 'omp_set_num_threads'.
_Example_:
     Lets suppose we have three scheduler instances 'IO', 'WRK0', and
     'WRK1' with 'GOMP_RTEMS_THREAD_POOLS' set to '"1@WRK0:3$4@WRK1"'.
     Then there are no thread pool restrictions for scheduler instance
     'IO'.  In the scheduler instance 'WRK0' there is one thread pool
     available.  Since no priority is specified for this scheduler
     instance, the worker thread inherits the priority of the OpenMP
     master thread that created it.  In the scheduler instance 'WRK1'
     there are three thread pools available and their worker threads run
     at priority four.


File: libgomp.info,  Node: Enabling OpenACC,  Next: OpenACC Runtime Library Routines,  Prev: Environment Variables,  Up: Top

4 Enabling OpenACC
******************

To activate the OpenACC extensions for C/C++ and Fortran, the
compile-time flag '-fopenacc' must be specified.  This enables the
OpenACC directive '#pragma acc' in C/C++ and '!$acc' directives in free
form, 'c$acc', '*$acc' and '!$acc' directives in fixed form, '!$'
conditional compilation sentinels in free form and 'c$', '*$' and '!$'
sentinels in fixed form, for Fortran.  The flag also arranges for
automatic linking of the OpenACC runtime library (*note OpenACC Runtime
Library Routines::).

   See <https://gcc.gnu.org/wiki/OpenACC> for more information.

   A complete description of all OpenACC directives accepted may be
found in the OpenACC (https://www.openacc.org) Application Programming
Interface manual, version 2.6.


File: libgomp.info,  Node: OpenACC Runtime Library Routines,  Next: OpenACC Environment Variables,  Prev: Enabling OpenACC,  Up: Top

5 OpenACC Runtime Library Routines
**********************************

The runtime routines described here are defined by section 3 of the
OpenACC specifications in version 2.6.  They have C linkage, and do not
throw exceptions.  Generally, they are available only for the host, with
the exception of 'acc_on_device', which is available for both the host
and the acceleration device.

* Menu:

* acc_get_num_devices::         Get number of devices for the given device
                                type.
* acc_set_device_type::         Set type of device accelerator to use.
* acc_get_device_type::         Get type of device accelerator to be used.
* acc_set_device_num::          Set device number to use.
* acc_get_device_num::          Get device number to be used.
* acc_get_property::            Get device property.
* acc_async_test::              Tests for completion of a specific asynchronous
                                operation.
* acc_async_test_all::          Tests for completion of all asynchronous
                                operations.
* acc_wait::                    Wait for completion of a specific asynchronous
                                operation.
* acc_wait_all::                Waits for completion of all asynchronous
                                operations.
* acc_wait_all_async::          Wait for completion of all asynchronous
                                operations.
* acc_wait_async::              Wait for completion of asynchronous operations.
* acc_init::                    Initialize runtime for a specific device type.
* acc_shutdown::                Shuts down the runtime for a specific device
                                type.
* acc_on_device::               Whether executing on a particular device
* acc_malloc::                  Allocate device memory.
* acc_free::                    Free device memory.
* acc_copyin::                  Allocate device memory and copy host memory to
                                it.
* acc_present_or_copyin::       If the data is not present on the device,
                                allocate device memory and copy from host
                                memory.
* acc_create::                  Allocate device memory and map it to host
                                memory.
* acc_present_or_create::       If the data is not present on the device,
                                allocate device memory and map it to host
                                memory.
* acc_copyout::                 Copy device memory to host memory.
* acc_delete::                  Free device memory.
* acc_update_device::           Update device memory from mapped host memory.
* acc_update_self::             Update host memory from mapped device memory.
* acc_map_data::                Map previously allocated device memory to host
                                memory.
* acc_unmap_data::              Unmap device memory from host memory.
* acc_deviceptr::               Get device pointer associated with specific
                                host address.
* acc_hostptr::                 Get host pointer associated with specific
                                device address.
* acc_is_present::              Indicate whether host variable / array is
                                present on device.
* acc_memcpy_to_device::        Copy host memory to device memory.
* acc_memcpy_from_device::      Copy device memory to host memory.
* acc_attach::                  Let device pointer point to device-pointer target.
* acc_detach::                  Let device pointer point to host-pointer target.

API routines for target platforms.

* acc_get_current_cuda_device:: Get CUDA device handle.
* acc_get_current_cuda_context::Get CUDA context handle.
* acc_get_cuda_stream::         Get CUDA stream handle.
* acc_set_cuda_stream::         Set CUDA stream handle.

API routines for the OpenACC Profiling Interface.

* acc_prof_register::           Register callbacks.
* acc_prof_unregister::         Unregister callbacks.
* acc_prof_lookup::             Obtain inquiry functions.
* acc_register_library::        Library registration.


File: libgomp.info,  Node: acc_get_num_devices,  Next: acc_set_device_type,  Up: OpenACC Runtime Library Routines

5.1 'acc_get_num_devices' - Get number of devices for given device type
=======================================================================

_Description_
     This function returns a value indicating the number of devices
     available for the device type specified in DEVICETYPE.

_C/C++_:
     _Prototype_:   'int acc_get_num_devices(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'integer function acc_get_num_devices(devicetype)'
                    'integer(kind=acc_device_kind) devicetype'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.1.


File: libgomp.info,  Node: acc_set_device_type,  Next: acc_get_device_type,  Prev: acc_get_num_devices,  Up: OpenACC Runtime Library Routines

5.2 'acc_set_device_type' - Set type of device accelerator to use.
==================================================================

_Description_
     This function indicates to the runtime library which device type,
     specified in DEVICETYPE, to use when executing a parallel or
     kernels region.

_C/C++_:
     _Prototype_:   'acc_set_device_type(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'subroutine acc_set_device_type(devicetype)'
                    'integer(kind=acc_device_kind) devicetype'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.2.


File: libgomp.info,  Node: acc_get_device_type,  Next: acc_set_device_num,  Prev: acc_set_device_type,  Up: OpenACC Runtime Library Routines

5.3 'acc_get_device_type' - Get type of device accelerator to be used.
======================================================================

_Description_
     This function returns what device type will be used when executing
     a parallel or kernels region.

     This function returns 'acc_device_none' if 'acc_get_device_type' is
     called from 'acc_ev_device_init_start', 'acc_ev_device_init_end'
     callbacks of the OpenACC Profiling Interface (*note OpenACC
     Profiling Interface::), that is, if the device is currently being
     initialized.

_C/C++_:
     _Prototype_:   'acc_device_t acc_get_device_type(void);'

_Fortran_:
     _Interface_:   'function acc_get_device_type(void)'
                    'integer(kind=acc_device_kind) acc_get_device_type'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.3.


File: libgomp.info,  Node: acc_set_device_num,  Next: acc_get_device_num,  Prev: acc_get_device_type,  Up: OpenACC Runtime Library Routines

5.4 'acc_set_device_num' - Set device number to use.
====================================================

_Description_
     This function will indicate to the runtime which device number,
     specified by DEVICENUM, associated with the specified device type
     DEVICETYPE.

_C/C++_:
     _Prototype_:   'acc_set_device_num(int devicenum, acc_device_t
                    devicetype);'

_Fortran_:
     _Interface_:   'subroutine acc_set_device_num(devicenum, devicetype)'
                    'integer devicenum'
                    'integer(kind=acc_device_kind) devicetype'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.4.


File: libgomp.info,  Node: acc_get_device_num,  Next: acc_get_property,  Prev: acc_set_device_num,  Up: OpenACC Runtime Library Routines

5.5 'acc_get_device_num' - Get device number to be used.
========================================================

_Description_
     This function returns which device number associated with the
     specified device type DEVICETYPE, will be used when executing a
     parallel or kernels region.

_C/C++_:
     _Prototype_:   'int acc_get_device_num(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'function acc_get_device_num(devicetype)'
                    'integer(kind=acc_device_kind) devicetype'
                    'integer acc_get_device_num'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.5.


File: libgomp.info,  Node: acc_get_property,  Next: acc_async_test,  Prev: acc_get_device_num,  Up: OpenACC Runtime Library Routines

5.6 'acc_get_property' - Get device property.
=============================================

_Description_
     These routines return the value of the specified PROPERTY for the
     device being queried according to DEVICENUM and DEVICETYPE.
     Integer-valued and string-valued properties are returned by
     'acc_get_property' and 'acc_get_property_string' respectively.  The
     Fortran 'acc_get_property_string' subroutine returns the string
     retrieved in its fourth argument while the remaining entry points
     are functions, which pass the return value as their result.

     Note for Fortran, only: the OpenACC technical committee corrected
     and, hence, modified the interface introduced in OpenACC 2.6.  The
     kind-value parameter 'acc_device_property' has been renamed to
     'acc_device_property_kind' for consistency and the return type of
     the 'acc_get_property' function is now a 'c_size_t' integer instead
     of a 'acc_device_property' integer.  The parameter
     'acc_device_property' will continue to be provided, but might be
     removed in a future version of GCC.

_C/C++_:
     _Prototype_:   'size_t acc_get_property(int devicenum, acc_device_t
                    devicetype, acc_device_property_t property);'
     _Prototype_:   'const char *acc_get_property_string(int devicenum,
                    acc_device_t devicetype, acc_device_property_t
                    property);'

_Fortran_:
     _Interface_:   'function acc_get_property(devicenum, devicetype,
                    property)'
     _Interface_:   'subroutine acc_get_property_string(devicenum,
                    devicetype, property, string)'
                    'use ISO_C_Binding, only: c_size_t'
                    'integer devicenum'
                    'integer(kind=acc_device_kind) devicetype'
                    'integer(kind=acc_device_property_kind) property'
                    'integer(kind=c_size_t) acc_get_property'
                    'character(*) string'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.6.


File: libgomp.info,  Node: acc_async_test,  Next: acc_async_test_all,  Prev: acc_get_property,  Up: OpenACC Runtime Library Routines

5.7 'acc_async_test' - Test for completion of a specific asynchronous operation.
================================================================================

_Description_
     This function tests for completion of the asynchronous operation
     specified in ARG.  In C/C++, a non-zero value will be returned to
     indicate the specified asynchronous operation has completed.  While
     Fortran will return a 'true'.  If the asynchronous operation has
     not completed, C/C++ returns a zero and Fortran returns a 'false'.

_C/C++_:
     _Prototype_:   'int acc_async_test(int arg);'

_Fortran_:
     _Interface_:   'function acc_async_test(arg)'
                    'integer(kind=acc_handle_kind) arg'
                    'logical acc_async_test'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.9.


File: libgomp.info,  Node: acc_async_test_all,  Next: acc_wait,  Prev: acc_async_test,  Up: OpenACC Runtime Library Routines

5.8 'acc_async_test_all' - Tests for completion of all asynchronous operations.
===============================================================================

_Description_
     This function tests for completion of all asynchronous operations.
     In C/C++, a non-zero value will be returned to indicate all
     asynchronous operations have completed.  While Fortran will return
     a 'true'.  If any asynchronous operation has not completed, C/C++
     returns a zero and Fortran returns a 'false'.

_C/C++_:
     _Prototype_:   'int acc_async_test_all(void);'

_Fortran_:
     _Interface_:   'function acc_async_test()'
                    'logical acc_get_device_num'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.10.


File: libgomp.info,  Node: acc_wait,  Next: acc_wait_all,  Prev: acc_async_test_all,  Up: OpenACC Runtime Library Routines

5.9 'acc_wait' - Wait for completion of a specific asynchronous operation.
==========================================================================

_Description_
     This function waits for completion of the asynchronous operation
     specified in ARG.

_C/C++_:
     _Prototype_:   'acc_wait(arg);'
     _Prototype     'acc_async_wait(arg);'
     (OpenACC 1.0
     compatibility)_:

_Fortran_:
     _Interface_:   'subroutine acc_wait(arg)'
                    'integer(acc_handle_kind) arg'
     _Interface     'subroutine acc_async_wait(arg)'
     (OpenACC 1.0
     compatibility)_:
                    'integer(acc_handle_kind) arg'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.11.


File: libgomp.info,  Node: acc_wait_all,  Next: acc_wait_all_async,  Prev: acc_wait,  Up: OpenACC Runtime Library Routines

5.10 'acc_wait_all' - Waits for completion of all asynchronous operations.
==========================================================================

_Description_
     This function waits for the completion of all asynchronous
     operations.

_C/C++_:
     _Prototype_:   'acc_wait_all(void);'
     _Prototype     'acc_async_wait_all(void);'
     (OpenACC 1.0
     compatibility)_:

_Fortran_:
     _Interface_:   'subroutine acc_wait_all()'
     _Interface     'subroutine acc_async_wait_all()'
     (OpenACC 1.0
     compatibility)_:

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.13.


File: libgomp.info,  Node: acc_wait_all_async,  Next: acc_wait_async,  Prev: acc_wait_all,  Up: OpenACC Runtime Library Routines

5.11 'acc_wait_all_async' - Wait for completion of all asynchronous operations.
===============================================================================

_Description_
     This function enqueues a wait operation on the queue ASYNC for any
     and all asynchronous operations that have been previously enqueued
     on any queue.

_C/C++_:
     _Prototype_:   'acc_wait_all_async(int async);'

_Fortran_:
     _Interface_:   'subroutine acc_wait_all_async(async)'
                    'integer(acc_handle_kind) async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.14.


File: libgomp.info,  Node: acc_wait_async,  Next: acc_init,  Prev: acc_wait_all_async,  Up: OpenACC Runtime Library Routines

5.12 'acc_wait_async' - Wait for completion of asynchronous operations.
=======================================================================

_Description_
     This function enqueues a wait operation on queue ASYNC for any and
     all asynchronous operations enqueued on queue ARG.

_C/C++_:
     _Prototype_:   'acc_wait_async(int arg, int async);'

_Fortran_:
     _Interface_:   'subroutine acc_wait_async(arg, async)'
                    'integer(acc_handle_kind) arg, async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.12.


File: libgomp.info,  Node: acc_init,  Next: acc_shutdown,  Prev: acc_wait_async,  Up: OpenACC Runtime Library Routines

5.13 'acc_init' - Initialize runtime for a specific device type.
================================================================

_Description_
     This function initializes the runtime for the device type specified
     in DEVICETYPE.

_C/C++_:
     _Prototype_:   'acc_init(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'subroutine acc_init(devicetype)'
                    'integer(acc_device_kind) devicetype'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.7.


File: libgomp.info,  Node: acc_shutdown,  Next: acc_on_device,  Prev: acc_init,  Up: OpenACC Runtime Library Routines

5.14 'acc_shutdown' - Shuts down the runtime for a specific device type.
========================================================================

_Description_
     This function shuts down the runtime for the device type specified
     in DEVICETYPE.

_C/C++_:
     _Prototype_:   'acc_shutdown(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'subroutine acc_shutdown(devicetype)'
                    'integer(acc_device_kind) devicetype'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.8.


File: libgomp.info,  Node: acc_on_device,  Next: acc_malloc,  Prev: acc_shutdown,  Up: OpenACC Runtime Library Routines

5.15 'acc_on_device' - Whether executing on a particular device
===============================================================

_Description_:
     This function returns whether the program is executing on a
     particular device specified in DEVICETYPE.  In C/C++ a non-zero
     value is returned to indicate the device is executing on the
     specified device type.  In Fortran, 'true' will be returned.  If
     the program is not executing on the specified device type C/C++
     will return a zero, while Fortran will return 'false'.

_C/C++_:
     _Prototype_:   'acc_on_device(acc_device_t devicetype);'

_Fortran_:
     _Interface_:   'function acc_on_device(devicetype)'
                    'integer(acc_device_kind) devicetype'
                    'logical acc_on_device'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.17.


File: libgomp.info,  Node: acc_malloc,  Next: acc_free,  Prev: acc_on_device,  Up: OpenACC Runtime Library Routines

5.16 'acc_malloc' - Allocate device memory.
===========================================

_Description_
     This function allocates LEN bytes of device memory.  It returns the
     device address of the allocated memory.

_C/C++_:
     _Prototype_:   'd_void* acc_malloc(size_t len);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.18.


File: libgomp.info,  Node: acc_free,  Next: acc_copyin,  Prev: acc_malloc,  Up: OpenACC Runtime Library Routines

5.17 'acc_free' - Free device memory.
=====================================

_Description_
     Free previously allocated device memory at the device address 'a'.

_C/C++_:
     _Prototype_:   'acc_free(d_void *a);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.19.


File: libgomp.info,  Node: acc_copyin,  Next: acc_present_or_copyin,  Prev: acc_free,  Up: OpenACC Runtime Library Routines

5.18 'acc_copyin' - Allocate device memory and copy host memory to it.
======================================================================

_Description_
     In C/C++, this function allocates LEN bytes of device memory and
     maps it to the specified host address in A.  The device address of
     the newly allocated device memory is returned.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'void *acc_copyin(h_void *a, size_t len);'
     _Prototype_:   'void *acc_copyin_async(h_void *a, size_t len, int
                    async);'

_Fortran_:
     _Interface_:   'subroutine acc_copyin(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_copyin(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_copyin_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_copyin_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.20.


File: libgomp.info,  Node: acc_present_or_copyin,  Next: acc_create,  Prev: acc_copyin,  Up: OpenACC Runtime Library Routines

5.19 'acc_present_or_copyin' - If the data is not present on the device, allocate device memory and copy from host memory.
==========================================================================================================================

_Description_
     This function tests if the host data specified by A and of length
     LEN is present or not.  If it is not present, then device memory
     will be allocated and the host memory copied.  The device address
     of the newly allocated device memory is returned.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

     Note that 'acc_present_or_copyin' and 'acc_pcopyin' exist for
     backward compatibility with OpenACC 2.0; use *note acc_copyin::
     instead.

_C/C++_:
     _Prototype_:   'void *acc_present_or_copyin(h_void *a, size_t len);'
     _Prototype_:   'void *acc_pcopyin(h_void *a, size_t len);'

_Fortran_:
     _Interface_:   'subroutine acc_present_or_copyin(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_present_or_copyin(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_pcopyin(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_pcopyin(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.20.


File: libgomp.info,  Node: acc_create,  Next: acc_present_or_create,  Prev: acc_present_or_copyin,  Up: OpenACC Runtime Library Routines

5.20 'acc_create' - Allocate device memory and map it to host memory.
=====================================================================

_Description_
     This function allocates device memory and maps it to host memory
     specified by the host address A with a length of LEN bytes.  In
     C/C++, the function returns the device address of the allocated
     device memory.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'void *acc_create(h_void *a, size_t len);'
     _Prototype_:   'void *acc_create_async(h_void *a, size_t len, int
                    async);'

_Fortran_:
     _Interface_:   'subroutine acc_create(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_create(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_create_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_create_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.21.


File: libgomp.info,  Node: acc_present_or_create,  Next: acc_copyout,  Prev: acc_create,  Up: OpenACC Runtime Library Routines

5.21 'acc_present_or_create' - If the data is not present on the device, allocate device memory and map it to host memory.
==========================================================================================================================

_Description_
     This function tests if the host data specified by A and of length
     LEN is present or not.  If it is not present, then device memory
     will be allocated and mapped to host memory.  In C/C++, the device
     address of the newly allocated device memory is returned.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

     Note that 'acc_present_or_create' and 'acc_pcreate' exist for
     backward compatibility with OpenACC 2.0; use *note acc_create::
     instead.

_C/C++_:
     _Prototype_:   'void *acc_present_or_create(h_void *a, size_t len)'
     _Prototype_:   'void *acc_pcreate(h_void *a, size_t len)'

_Fortran_:
     _Interface_:   'subroutine acc_present_or_create(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_present_or_create(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_pcreate(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_pcreate(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.21.


File: libgomp.info,  Node: acc_copyout,  Next: acc_delete,  Prev: acc_present_or_create,  Up: OpenACC Runtime Library Routines

5.22 'acc_copyout' - Copy device memory to host memory.
=======================================================

_Description_
     This function copies mapped device memory to host memory which is
     specified by host address A for a length LEN bytes in C/C++.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'acc_copyout(h_void *a, size_t len);'
     _Prototype_:   'acc_copyout_async(h_void *a, size_t len, int async);'
     _Prototype_:   'acc_copyout_finalize(h_void *a, size_t len);'
     _Prototype_:   'acc_copyout_finalize_async(h_void *a, size_t len, int
                    async);'

_Fortran_:
     _Interface_:   'subroutine acc_copyout(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_copyout(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_copyout_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_copyout_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_copyout_finalize(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_copyout_finalize(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_copyout_finalize_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_copyout_finalize_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.22.


File: libgomp.info,  Node: acc_delete,  Next: acc_update_device,  Prev: acc_copyout,  Up: OpenACC Runtime Library Routines

5.23 'acc_delete' - Free device memory.
=======================================

_Description_
     This function frees previously allocated device memory specified by
     the device address A and the length of LEN bytes.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'acc_delete(h_void *a, size_t len);'
     _Prototype_:   'acc_delete_async(h_void *a, size_t len, int async);'
     _Prototype_:   'acc_delete_finalize(h_void *a, size_t len);'
     _Prototype_:   'acc_delete_finalize_async(h_void *a, size_t len, int
                    async);'

_Fortran_:
     _Interface_:   'subroutine acc_delete(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_delete(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_delete_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_delete_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_delete_finalize(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_delete_finalize(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_delete_async_finalize(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_delete_async_finalize(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.23.


File: libgomp.info,  Node: acc_update_device,  Next: acc_update_self,  Prev: acc_delete,  Up: OpenACC Runtime Library Routines

5.24 'acc_update_device' - Update device memory from mapped host memory.
========================================================================

_Description_
     This function updates the device copy from the previously mapped
     host memory.  The host memory is specified with the host address A
     and a length of LEN bytes.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'acc_update_device(h_void *a, size_t len);'
     _Prototype_:   'acc_update_device(h_void *a, size_t len, async);'

_Fortran_:
     _Interface_:   'subroutine acc_update_device(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_update_device(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_update_device_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_update_device_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.24.


File: libgomp.info,  Node: acc_update_self,  Next: acc_map_data,  Prev: acc_update_device,  Up: OpenACC Runtime Library Routines

5.25 'acc_update_self' - Update host memory from mapped device memory.
======================================================================

_Description_
     This function updates the host copy from the previously mapped
     device memory.  The host memory is specified with the host address
     A and a length of LEN bytes.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.

_C/C++_:
     _Prototype_:   'acc_update_self(h_void *a, size_t len);'
     _Prototype_:   'acc_update_self_async(h_void *a, size_t len, int
                    async);'

_Fortran_:
     _Interface_:   'subroutine acc_update_self(a)'
                    'type, dimension(:[,:]...) :: a'
     _Interface_:   'subroutine acc_update_self(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
     _Interface_:   'subroutine acc_update_self_async(a, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer(acc_handle_kind) :: async'
     _Interface_:   'subroutine acc_update_self_async(a, len, async)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'integer(acc_handle_kind) :: async'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.25.


File: libgomp.info,  Node: acc_map_data,  Next: acc_unmap_data,  Prev: acc_update_self,  Up: OpenACC Runtime Library Routines

5.26 'acc_map_data' - Map previously allocated device memory to host memory.
============================================================================

_Description_
     This function maps previously allocated device and host memory.
     The device memory is specified with the device address D.  The host
     memory is specified with the host address H and a length of LEN.

_C/C++_:
     _Prototype_:   'acc_map_data(h_void *h, d_void *d, size_t len);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.26.


File: libgomp.info,  Node: acc_unmap_data,  Next: acc_deviceptr,  Prev: acc_map_data,  Up: OpenACC Runtime Library Routines

5.27 'acc_unmap_data' - Unmap device memory from host memory.
=============================================================

_Description_
     This function unmaps previously mapped device and host memory.  The
     latter specified by H.

_C/C++_:
     _Prototype_:   'acc_unmap_data(h_void *h);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.27.


File: libgomp.info,  Node: acc_deviceptr,  Next: acc_hostptr,  Prev: acc_unmap_data,  Up: OpenACC Runtime Library Routines

5.28 'acc_deviceptr' - Get device pointer associated with specific host address.
================================================================================

_Description_
     This function returns the device address that has been mapped to
     the host address specified by H.

_C/C++_:
     _Prototype_:   'void *acc_deviceptr(h_void *h);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.28.


File: libgomp.info,  Node: acc_hostptr,  Next: acc_is_present,  Prev: acc_deviceptr,  Up: OpenACC Runtime Library Routines

5.29 'acc_hostptr' - Get host pointer associated with specific device address.
==============================================================================

_Description_
     This function returns the host address that has been mapped to the
     device address specified by D.

_C/C++_:
     _Prototype_:   'void *acc_hostptr(d_void *d);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.29.


File: libgomp.info,  Node: acc_is_present,  Next: acc_memcpy_to_device,  Prev: acc_hostptr,  Up: OpenACC Runtime Library Routines

5.30 'acc_is_present' - Indicate whether host variable / array is present on device.
====================================================================================

_Description_
     This function indicates whether the specified host address in A and
     a length of LEN bytes is present on the device.  In C/C++, a
     non-zero value is returned to indicate the presence of the mapped
     memory on the device.  A zero is returned to indicate the memory is
     not mapped on the device.

     In Fortran, two (2) forms are supported.  In the first form, A
     specifies a contiguous array section.  The second form A specifies
     a variable or array element and LEN specifies the length in bytes.
     If the host memory is mapped to device memory, then a 'true' is
     returned.  Otherwise, a 'false' is return to indicate the mapped
     memory is not present.

_C/C++_:
     _Prototype_:   'int acc_is_present(h_void *a, size_t len);'

_Fortran_:
     _Interface_:   'function acc_is_present(a)'
                    'type, dimension(:[,:]...) :: a'
                    'logical acc_is_present'
     _Interface_:   'function acc_is_present(a, len)'
                    'type, dimension(:[,:]...) :: a'
                    'integer len'
                    'logical acc_is_present'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.30.


File: libgomp.info,  Node: acc_memcpy_to_device,  Next: acc_memcpy_from_device,  Prev: acc_is_present,  Up: OpenACC Runtime Library Routines

5.31 'acc_memcpy_to_device' - Copy host memory to device memory.
================================================================

_Description_
     This function copies host memory specified by host address of SRC
     to device memory specified by the device address DEST for a length
     of BYTES bytes.

_C/C++_:
     _Prototype_:   'acc_memcpy_to_device(d_void *dest, h_void *src, size_t
                    bytes);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.31.


File: libgomp.info,  Node: acc_memcpy_from_device,  Next: acc_attach,  Prev: acc_memcpy_to_device,  Up: OpenACC Runtime Library Routines

5.32 'acc_memcpy_from_device' - Copy device memory to host memory.
==================================================================

_Description_
     This function copies host memory specified by host address of SRC
     from device memory specified by the device address DEST for a
     length of BYTES bytes.

_C/C++_:
     _Prototype_:   'acc_memcpy_from_device(d_void *dest, h_void *src,
                    size_t bytes);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.32.


File: libgomp.info,  Node: acc_attach,  Next: acc_detach,  Prev: acc_memcpy_from_device,  Up: OpenACC Runtime Library Routines

5.33 'acc_attach' - Let device pointer point to device-pointer target.
======================================================================

_Description_
     This function updates a pointer on the device from pointing to a
     host-pointer address to pointing to the corresponding device data.

_C/C++_:
     _Prototype_:   'acc_attach(h_void **ptr);'
     _Prototype_:   'acc_attach_async(h_void **ptr, int async);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.34.


File: libgomp.info,  Node: acc_detach,  Next: acc_get_current_cuda_device,  Prev: acc_attach,  Up: OpenACC Runtime Library Routines

5.34 'acc_detach' - Let device pointer point to host-pointer target.
====================================================================

_Description_
     This function updates a pointer on the device from pointing to a
     device-pointer address to pointing to the corresponding host data.

_C/C++_:
     _Prototype_:   'acc_detach(h_void **ptr);'
     _Prototype_:   'acc_detach_async(h_void **ptr, int async);'
     _Prototype_:   'acc_detach_finalize(h_void **ptr);'
     _Prototype_:   'acc_detach_finalize_async(h_void **ptr, int async);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     3.2.35.


File: libgomp.info,  Node: acc_get_current_cuda_device,  Next: acc_get_current_cuda_context,  Prev: acc_detach,  Up: OpenACC Runtime Library Routines

5.35 'acc_get_current_cuda_device' - Get CUDA device handle.
============================================================

_Description_
     This function returns the CUDA device handle.  This handle is the
     same as used by the CUDA Runtime or Driver API's.

_C/C++_:
     _Prototype_:   'void *acc_get_current_cuda_device(void);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     A.2.1.1.


File: libgomp.info,  Node: acc_get_current_cuda_context,  Next: acc_get_cuda_stream,  Prev: acc_get_current_cuda_device,  Up: OpenACC Runtime Library Routines

5.36 'acc_get_current_cuda_context' - Get CUDA context handle.
==============================================================

_Description_
     This function returns the CUDA context handle.  This handle is the
     same as used by the CUDA Runtime or Driver API's.

_C/C++_:
     _Prototype_:   'void *acc_get_current_cuda_context(void);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     A.2.1.2.


File: libgomp.info,  Node: acc_get_cuda_stream,  Next: acc_set_cuda_stream,  Prev: acc_get_current_cuda_context,  Up: OpenACC Runtime Library Routines

5.37 'acc_get_cuda_stream' - Get CUDA stream handle.
====================================================

_Description_
     This function returns the CUDA stream handle for the queue ASYNC.
     This handle is the same as used by the CUDA Runtime or Driver
     API's.

_C/C++_:
     _Prototype_:   'void *acc_get_cuda_stream(int async);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     A.2.1.3.


File: libgomp.info,  Node: acc_set_cuda_stream,  Next: acc_prof_register,  Prev: acc_get_cuda_stream,  Up: OpenACC Runtime Library Routines

5.38 'acc_set_cuda_stream' - Set CUDA stream handle.
====================================================

_Description_
     This function associates the stream handle specified by STREAM with
     the queue ASYNC.

     This cannot be used to change the stream handle associated with
     'acc_async_sync'.

     The return value is not specified.

_C/C++_:
     _Prototype_:   'int acc_set_cuda_stream(int async, void *stream);'

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section
     A.2.1.4.


File: libgomp.info,  Node: acc_prof_register,  Next: acc_prof_unregister,  Prev: acc_set_cuda_stream,  Up: OpenACC Runtime Library Routines

5.39 'acc_prof_register' - Register callbacks.
==============================================

_Description_:
     This function registers callbacks.

_C/C++_:
     _Prototype_:   'void acc_prof_register (acc_event_t, acc_prof_callback,
                    acc_register_t);'

_See also_:
     *note OpenACC Profiling Interface::

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 5.3.


File: libgomp.info,  Node: acc_prof_unregister,  Next: acc_prof_lookup,  Prev: acc_prof_register,  Up: OpenACC Runtime Library Routines

5.40 'acc_prof_unregister' - Unregister callbacks.
==================================================

_Description_:
     This function unregisters callbacks.

_C/C++_:
     _Prototype_:   'void acc_prof_unregister (acc_event_t,
                    acc_prof_callback, acc_register_t);'

_See also_:
     *note OpenACC Profiling Interface::

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 5.3.


File: libgomp.info,  Node: acc_prof_lookup,  Next: acc_register_library,  Prev: acc_prof_unregister,  Up: OpenACC Runtime Library Routines

5.41 'acc_prof_lookup' - Obtain inquiry functions.
==================================================

_Description_:
     Function to obtain inquiry functions.

_C/C++_:
     _Prototype_:   'acc_query_fn acc_prof_lookup (const char *);'

_See also_:
     *note OpenACC Profiling Interface::

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 5.3.


File: libgomp.info,  Node: acc_register_library,  Prev: acc_prof_lookup,  Up: OpenACC Runtime Library Routines

5.42 'acc_register_library' - Library registration.
===================================================

_Description_:
     Function for library registration.

_C/C++_:
     _Prototype_:   'void acc_register_library (acc_prof_reg, acc_prof_reg,
                    acc_prof_lookup_func);'

_See also_:
     *note OpenACC Profiling Interface::, *note ACC_PROFLIB::

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 5.3.


File: libgomp.info,  Node: OpenACC Environment Variables,  Next: CUDA Streams Usage,  Prev: OpenACC Runtime Library Routines,  Up: Top

6 OpenACC Environment Variables
*******************************

The variables 'ACC_DEVICE_TYPE' and 'ACC_DEVICE_NUM' are defined by
section 4 of the OpenACC specification in version 2.0.  The variable
'ACC_PROFLIB' is defined by section 4 of the OpenACC specification in
version 2.6.  The variable 'GCC_ACC_NOTIFY' is used for diagnostic
purposes.

* Menu:

* ACC_DEVICE_TYPE::
* ACC_DEVICE_NUM::
* ACC_PROFLIB::
* GCC_ACC_NOTIFY::


File: libgomp.info,  Node: ACC_DEVICE_TYPE,  Next: ACC_DEVICE_NUM,  Up: OpenACC Environment Variables

6.1 'ACC_DEVICE_TYPE'
=====================

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 4.1.


File: libgomp.info,  Node: ACC_DEVICE_NUM,  Next: ACC_PROFLIB,  Prev: ACC_DEVICE_TYPE,  Up: OpenACC Environment Variables

6.2 'ACC_DEVICE_NUM'
====================

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 4.2.


File: libgomp.info,  Node: ACC_PROFLIB,  Next: GCC_ACC_NOTIFY,  Prev: ACC_DEVICE_NUM,  Up: OpenACC Environment Variables

6.3 'ACC_PROFLIB'
=================

_See also_:
     *note acc_register_library::, *note OpenACC Profiling Interface::

_Reference_:
     OpenACC specification v2.6 (https://www.openacc.org), section 4.3.


File: libgomp.info,  Node: GCC_ACC_NOTIFY,  Prev: ACC_PROFLIB,  Up: OpenACC Environment Variables

6.4 'GCC_ACC_NOTIFY'
====================

_Description_:
     Print debug information pertaining to the accelerator.


File: libgomp.info,  Node: CUDA Streams Usage,  Next: OpenACC Library Interoperability,  Prev: OpenACC Environment Variables,  Up: Top

7 CUDA Streams Usage
********************

This applies to the 'nvptx' plugin only.

   The library provides elements that perform asynchronous movement of
data and asynchronous operation of computing constructs.  This
asynchronous functionality is implemented by making use of CUDA
streams(1).

   The primary means by that the asynchronous functionality is accessed
is through the use of those OpenACC directives which make use of the
'async' and 'wait' clauses.  When the 'async' clause is first used with
a directive, it creates a CUDA stream.  If an 'async-argument' is used
with the 'async' clause, then the stream is associated with the
specified 'async-argument'.

   Following the creation of an association between a CUDA stream and
the 'async-argument' of an 'async' clause, both the 'wait' clause and
the 'wait' directive can be used.  When either the clause or directive
is used after stream creation, it creates a rendezvous point whereby
execution waits until all operations associated with the
'async-argument', that is, stream, have completed.

   Normally, the management of the streams that are created as a result
of using the 'async' clause, is done without any intervention by the
caller.  This implies the association between the 'async-argument' and
the CUDA stream will be maintained for the lifetime of the program.
However, this association can be changed through the use of the library
function 'acc_set_cuda_stream'.  When the function 'acc_set_cuda_stream'
is called, the CUDA stream that was originally associated with the
'async' clause will be destroyed.  Caution should be taken when changing
the association as subsequent references to the 'async-argument' refer
to a different CUDA stream.

   ---------- Footnotes ----------

   (1) See "Stream Management" in "CUDA Driver API", TRM-06703-001,
Version 5.5, for additional information


File: libgomp.info,  Node: OpenACC Library Interoperability,  Next: OpenACC Profiling Interface,  Prev: CUDA Streams Usage,  Up: Top

8 OpenACC Library Interoperability
**********************************

8.1 Introduction
================

The OpenACC library uses the CUDA Driver API, and may interact with
programs that use the Runtime library directly, or another library based
on the Runtime library, e.g., CUBLAS(1). This chapter describes the use
cases and what changes are required in order to use both the OpenACC
library and the CUBLAS and Runtime libraries within a program.

8.2 First invocation: NVIDIA CUBLAS library API
===============================================

In this first use case (see below), a function in the CUBLAS library is
called prior to any of the functions in the OpenACC library.  More
specifically, the function 'cublasCreate()'.

   When invoked, the function initializes the library and allocates the
hardware resources on the host and the device on behalf of the caller.
Once the initialization and allocation has completed, a handle is
returned to the caller.  The OpenACC library also requires
initialization and allocation of hardware resources.  Since the CUBLAS
library has already allocated the hardware resources for the device, all
that is left to do is to initialize the OpenACC library and acquire the
hardware resources on the host.

   Prior to calling the OpenACC function that initializes the library
and allocate the host hardware resources, you need to acquire the device
number that was allocated during the call to 'cublasCreate()'.  The
invoking of the runtime library function 'cudaGetDevice()' accomplishes
this.  Once acquired, the device number is passed along with the device
type as parameters to the OpenACC library function
'acc_set_device_num()'.

   Once the call to 'acc_set_device_num()' has completed, the OpenACC
library uses the context that was created during the call to
'cublasCreate()'.  In other words, both libraries will be sharing the
same context.

         /* Create the handle */
         s = cublasCreate(&h);
         if (s != CUBLAS_STATUS_SUCCESS)
         {
             fprintf(stderr, "cublasCreate failed %d\n", s);
             exit(EXIT_FAILURE);
         }

         /* Get the device number */
         e = cudaGetDevice(&dev);
         if (e != cudaSuccess)
         {
             fprintf(stderr, "cudaGetDevice failed %d\n", e);
             exit(EXIT_FAILURE);
         }

         /* Initialize OpenACC library and use device 'dev' */
         acc_set_device_num(dev, acc_device_nvidia);

                              Use Case 1

8.3 First invocation: OpenACC library API
=========================================

In this second use case (see below), a function in the OpenACC library
is called prior to any of the functions in the CUBLAS library.  More
specificially, the function 'acc_set_device_num()'.

   In the use case presented here, the function 'acc_set_device_num()'
is used to both initialize the OpenACC library and allocate the hardware
resources on the host and the device.  In the call to the function, the
call parameters specify which device to use and what device type to use,
i.e., 'acc_device_nvidia'.  It should be noted that this is but one
method to initialize the OpenACC library and allocate the appropriate
hardware resources.  Other methods are available through the use of
environment variables and these will be discussed in the next section.

   Once the call to 'acc_set_device_num()' has completed, other OpenACC
functions can be called as seen with multiple calls being made to
'acc_copyin()'.  In addition, calls can be made to functions in the
CUBLAS library.  In the use case a call to 'cublasCreate()' is made
subsequent to the calls to 'acc_copyin()'.  As seen in the previous use
case, a call to 'cublasCreate()' initializes the CUBLAS library and
allocates the hardware resources on the host and the device.  However,
since the device has already been allocated, 'cublasCreate()' will only
initialize the CUBLAS library and allocate the appropriate hardware
resources on the host.  The context that was created as part of the
OpenACC initialization is shared with the CUBLAS library, similarly to
the first use case.

         dev = 0;

         acc_set_device_num(dev, acc_device_nvidia);

         /* Copy the first set to the device */
         d_X = acc_copyin(&h_X[0], N * sizeof (float));
         if (d_X == NULL)
         {
             fprintf(stderr, "copyin error h_X\n");
             exit(EXIT_FAILURE);
         }

         /* Copy the second set to the device */
         d_Y = acc_copyin(&h_Y1[0], N * sizeof (float));
         if (d_Y == NULL)
         {
             fprintf(stderr, "copyin error h_Y1\n");
             exit(EXIT_FAILURE);
         }

         /* Create the handle */
         s = cublasCreate(&h);
         if (s != CUBLAS_STATUS_SUCCESS)
         {
             fprintf(stderr, "cublasCreate failed %d\n", s);
             exit(EXIT_FAILURE);
         }

         /* Perform saxpy using CUBLAS library function */
         s = cublasSaxpy(h, N, &alpha, d_X, 1, d_Y, 1);
         if (s != CUBLAS_STATUS_SUCCESS)
         {
             fprintf(stderr, "cublasSaxpy failed %d\n", s);
             exit(EXIT_FAILURE);
         }

         /* Copy the results from the device */
         acc_memcpy_from_device(&h_Y1[0], d_Y, N * sizeof (float));

                              Use Case 2

8.4 OpenACC library and environment variables
=============================================

There are two environment variables associated with the OpenACC library
that may be used to control the device type and device number:
'ACC_DEVICE_TYPE' and 'ACC_DEVICE_NUM', respectively.  These two
environment variables can be used as an alternative to calling
'acc_set_device_num()'.  As seen in the second use case, the device type
and device number were specified using 'acc_set_device_num()'.  If
however, the aforementioned environment variables were set, then the
call to 'acc_set_device_num()' would not be required.

   The use of the environment variables is only relevant when an OpenACC
function is called prior to a call to 'cudaCreate()'.  If 'cudaCreate()'
is called prior to a call to an OpenACC function, then you must call
'acc_set_device_num()'(2)

   ---------- Footnotes ----------

   (1) See section 2.26, "Interactions with the CUDA Driver API" in
"CUDA Runtime API", Version 5.5, and section 2.27, "VDPAU
Interoperability", in "CUDA Driver API", TRM-06703-001, Version 5.5, for
additional information on library interoperability.

   (2) More complete information about 'ACC_DEVICE_TYPE' and
'ACC_DEVICE_NUM' can be found in sections 4.1 and 4.2 of the OpenACC
(https://www.openacc.org) Application Programming Interface”, Version
2.6.


File: libgomp.info,  Node: OpenACC Profiling Interface,  Next: The libgomp ABI,  Prev: OpenACC Library Interoperability,  Up: Top

9 OpenACC Profiling Interface
*****************************

9.1 Implementation Status and Implementation-Defined Behavior
=============================================================

We're implementing the OpenACC Profiling Interface as defined by the
OpenACC 2.6 specification.  We're clarifying some aspects here as
_implementation-defined behavior_, while they're still under discussion
within the OpenACC Technical Committee.

   This implementation is tuned to keep the performance impact as low as
possible for the (very common) case that the Profiling Interface is not
enabled.  This is relevant, as the Profiling Interface affects all the
_hot_ code paths (in the target code, not in the offloaded code).  Users
of the OpenACC Profiling Interface can be expected to understand that
performance will be impacted to some degree once the Profiling Interface
has gotten enabled: for example, because of the _runtime_ (libgomp)
calling into a third-party _library_ for every event that has been
registered.

   We're not yet accounting for the fact that 'OpenACC events may occur
during event processing'.  We just handle one case specially, as
required by CUDA 9.0 'nvprof', that 'acc_get_device_type' (*note
acc_get_device_type::)) may be called from 'acc_ev_device_init_start',
'acc_ev_device_init_end' callbacks.

   We're not yet implementing initialization via a
'acc_register_library' function that is either statically linked in, or
dynamically via 'LD_PRELOAD'.  Initialization via 'acc_register_library'
functions dynamically loaded via the 'ACC_PROFLIB' environment variable
does work, as does directly calling 'acc_prof_register',
'acc_prof_unregister', 'acc_prof_lookup'.

   As currently there are no inquiry functions defined, calls to
'acc_prof_lookup' will always return 'NULL'.

   There aren't separate _start_, _stop_ events defined for the event
types 'acc_ev_create', 'acc_ev_delete', 'acc_ev_alloc', 'acc_ev_free'.
It's not clear if these should be triggered before or after the actual
device-specific call is made.  We trigger them after.

   Remarks about data provided to callbacks:

'acc_prof_info.event_type'
     It's not clear if for _nested_ event callbacks (for example,
     'acc_ev_enqueue_launch_start' as part of a parent compute
     construct), this should be set for the nested event
     ('acc_ev_enqueue_launch_start'), or if the value of the parent
     construct should remain ('acc_ev_compute_construct_start').  In
     this implementation, the value will generally correspond to the
     innermost nested event type.

'acc_prof_info.device_type'

        * For 'acc_ev_compute_construct_start', and in presence of an
          'if' clause with _false_ argument, this will still refer to
          the offloading device type.  It's not clear if that's the
          expected behavior.

        * Complementary to the item before, for
          'acc_ev_compute_construct_end', this is set to
          'acc_device_host' in presence of an 'if' clause with _false_
          argument.  It's not clear if that's the expected behavior.

'acc_prof_info.thread_id'
     Always '-1'; not yet implemented.

'acc_prof_info.async'

        * Not yet implemented correctly for
          'acc_ev_compute_construct_start'.

        * In a compute construct, for host-fallback
          execution/'acc_device_host' it will always be
          'acc_async_sync'.  It's not clear if that's the expected
          behavior.

        * For 'acc_ev_device_init_start' and 'acc_ev_device_init_end',
          it will always be 'acc_async_sync'.  It's not clear if that's
          the expected behavior.

'acc_prof_info.async_queue'
     There is no 'limited number of asynchronous queues' in libgomp.
     This will always have the same value as 'acc_prof_info.async'.

'acc_prof_info.src_file'
     Always 'NULL'; not yet implemented.

'acc_prof_info.func_name'
     Always 'NULL'; not yet implemented.

'acc_prof_info.line_no'
     Always '-1'; not yet implemented.

'acc_prof_info.end_line_no'
     Always '-1'; not yet implemented.

'acc_prof_info.func_line_no'
     Always '-1'; not yet implemented.

'acc_prof_info.func_end_line_no'
     Always '-1'; not yet implemented.

'acc_event_info.event_type', 'acc_event_info.*.event_type'
     Relating to 'acc_prof_info.event_type' discussed above, in this
     implementation, this will always be the same value as
     'acc_prof_info.event_type'.

'acc_event_info.*.parent_construct'

        * Will be 'acc_construct_parallel' for all OpenACC compute
          constructs as well as many OpenACC Runtime API calls; should
          be the one matching the actual construct, or
          'acc_construct_runtime_api', respectively.

        * Will be 'acc_construct_enter_data' or
          'acc_construct_exit_data' when processing variable mappings
          specified in OpenACC _declare_ directives; should be
          'acc_construct_declare'.

        * For implicit 'acc_ev_device_init_start',
          'acc_ev_device_init_end', and explicit as well as implicit
          'acc_ev_alloc', 'acc_ev_free', 'acc_ev_enqueue_upload_start',
          'acc_ev_enqueue_upload_end', 'acc_ev_enqueue_download_start',
          and 'acc_ev_enqueue_download_end', will be
          'acc_construct_parallel'; should reflect the real parent
          construct.

'acc_event_info.*.implicit'
     For 'acc_ev_alloc', 'acc_ev_free', 'acc_ev_enqueue_upload_start',
     'acc_ev_enqueue_upload_end', 'acc_ev_enqueue_download_start', and
     'acc_ev_enqueue_download_end', this currently will be '1' also for
     explicit usage.

'acc_event_info.data_event.var_name'
     Always 'NULL'; not yet implemented.

'acc_event_info.data_event.host_ptr'
     For 'acc_ev_alloc', and 'acc_ev_free', this is always 'NULL'.

'typedef union acc_api_info'
     ... as printed in '5.2.3. Third Argument: API-Specific
     Information'.  This should obviously be 'typedef _struct_
     acc_api_info'.

'acc_api_info.device_api'
     Possibly not yet implemented correctly for
     'acc_ev_compute_construct_start', 'acc_ev_device_init_start',
     'acc_ev_device_init_end': will always be 'acc_device_api_none' for
     these event types.  For 'acc_ev_enter_data_start', it will be
     'acc_device_api_none' in some cases.

'acc_api_info.device_type'
     Always the same as 'acc_prof_info.device_type'.

'acc_api_info.vendor'
     Always '-1'; not yet implemented.

'acc_api_info.device_handle'
     Always 'NULL'; not yet implemented.

'acc_api_info.context_handle'
     Always 'NULL'; not yet implemented.

'acc_api_info.async_handle'
     Always 'NULL'; not yet implemented.

   Remarks about certain event types:

'acc_ev_device_init_start', 'acc_ev_device_init_end'

        * Whan a compute construct triggers implicit
          'acc_ev_device_init_start' and 'acc_ev_device_init_end'
          events, they currently aren't _nested within_ the
          corresponding 'acc_ev_compute_construct_start' and
          'acc_ev_compute_construct_end', but they're currently observed
          _before_ 'acc_ev_compute_construct_start'.  It's not clear
          what to do: the standard asks us provide a lot of details to
          the 'acc_ev_compute_construct_start' callback, without
          (implicitly) initializing a device before?

        * Callbacks for these event types will not be invoked for calls
          to the 'acc_set_device_type' and 'acc_set_device_num'
          functions.  It's not clear if they should be.

'acc_ev_enter_data_start', 'acc_ev_enter_data_end', 'acc_ev_exit_data_start', 'acc_ev_exit_data_end'

        * Callbacks for these event types will also be invoked for
          OpenACC _host_data_ constructs.  It's not clear if they should
          be.

        * Callbacks for these event types will also be invoked when
          processing variable mappings specified in OpenACC _declare_
          directives.  It's not clear if they should be.

   Callbacks for the following event types will be invoked, but dispatch
and information provided therein has not yet been thoroughly reviewed:

   * 'acc_ev_alloc'
   * 'acc_ev_free'
   * 'acc_ev_update_start', 'acc_ev_update_end'
   * 'acc_ev_enqueue_upload_start', 'acc_ev_enqueue_upload_end'
   * 'acc_ev_enqueue_download_start', 'acc_ev_enqueue_download_end'

   During device initialization, and finalization, respectively,
callbacks for the following event types will not yet be invoked:

   * 'acc_ev_alloc'
   * 'acc_ev_free'

   Callbacks for the following event types have not yet been
implemented, so currently won't be invoked:

   * 'acc_ev_device_shutdown_start', 'acc_ev_device_shutdown_end'
   * 'acc_ev_runtime_shutdown'
   * 'acc_ev_create', 'acc_ev_delete'
   * 'acc_ev_wait_start', 'acc_ev_wait_end'

   For the following runtime library functions, not all expected
callbacks will be invoked (mostly concerning implicit device
initialization):

   * 'acc_get_num_devices'
   * 'acc_set_device_type'
   * 'acc_get_device_type'
   * 'acc_set_device_num'
   * 'acc_get_device_num'
   * 'acc_init'
   * 'acc_shutdown'

   Aside from implicit device initialization, for the following runtime
library functions, no callbacks will be invoked for shared-memory
offloading devices (it's not clear if they should be):

   * 'acc_malloc'
   * 'acc_free'
   * 'acc_copyin', 'acc_present_or_copyin', 'acc_copyin_async'
   * 'acc_create', 'acc_present_or_create', 'acc_create_async'
   * 'acc_copyout', 'acc_copyout_async', 'acc_copyout_finalize',
     'acc_copyout_finalize_async'
   * 'acc_delete', 'acc_delete_async', 'acc_delete_finalize',
     'acc_delete_finalize_async'
   * 'acc_update_device', 'acc_update_device_async'
   * 'acc_update_self', 'acc_update_self_async'
   * 'acc_map_data', 'acc_unmap_data'
   * 'acc_memcpy_to_device', 'acc_memcpy_to_device_async'
   * 'acc_memcpy_from_device', 'acc_memcpy_from_device_async'


File: libgomp.info,  Node: The libgomp ABI,  Next: Reporting Bugs,  Prev: OpenACC Profiling Interface,  Up: Top

10 The libgomp ABI
******************

The following sections present notes on the external ABI as presented by
libgomp.  Only maintainers should need them.

* Menu:

* Implementing MASTER construct::
* Implementing CRITICAL construct::
* Implementing ATOMIC construct::
* Implementing FLUSH construct::
* Implementing BARRIER construct::
* Implementing THREADPRIVATE construct::
* Implementing PRIVATE clause::
* Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses::
* Implementing REDUCTION clause::
* Implementing PARALLEL construct::
* Implementing FOR construct::
* Implementing ORDERED construct::
* Implementing SECTIONS construct::
* Implementing SINGLE construct::
* Implementing OpenACC's PARALLEL construct::


File: libgomp.info,  Node: Implementing MASTER construct,  Next: Implementing CRITICAL construct,  Up: The libgomp ABI

10.1 Implementing MASTER construct
==================================

     if (omp_get_thread_num () == 0)
       block

   Alternately, we generate two copies of the parallel subfunction and
only include this in the version run by the master thread.  Surely this
is not worthwhile though...


File: libgomp.info,  Node: Implementing CRITICAL construct,  Next: Implementing ATOMIC construct,  Prev: Implementing MASTER construct,  Up: The libgomp ABI

10.2 Implementing CRITICAL construct
====================================

Without a specified name,

       void GOMP_critical_start (void);
       void GOMP_critical_end (void);

   so that we don't get COPY relocations from libgomp to the main
application.

   With a specified name, use omp_set_lock and omp_unset_lock with name
being transformed into a variable declared like

       omp_lock_t gomp_critical_user_<name> __attribute__((common))

   Ideally the ABI would specify that all zero is a valid unlocked
state, and so we wouldn't need to initialize this at startup.


File: libgomp.info,  Node: Implementing ATOMIC construct,  Next: Implementing FLUSH construct,  Prev: Implementing CRITICAL construct,  Up: The libgomp ABI

10.3 Implementing ATOMIC construct
==================================

The target should implement the '__sync' builtins.

   Failing that we could add

       void GOMP_atomic_enter (void)
       void GOMP_atomic_exit (void)

   which reuses the regular lock code, but with yet another lock object
private to the library.


File: libgomp.info,  Node: Implementing FLUSH construct,  Next: Implementing BARRIER construct,  Prev: Implementing ATOMIC construct,  Up: The libgomp ABI

10.4 Implementing FLUSH construct
=================================

Expands to the '__sync_synchronize' builtin.


File: libgomp.info,  Node: Implementing BARRIER construct,  Next: Implementing THREADPRIVATE construct,  Prev: Implementing FLUSH construct,  Up: The libgomp ABI

10.5 Implementing BARRIER construct
===================================

       void GOMP_barrier (void)


File: libgomp.info,  Node: Implementing THREADPRIVATE construct,  Next: Implementing PRIVATE clause,  Prev: Implementing BARRIER construct,  Up: The libgomp ABI

10.6 Implementing THREADPRIVATE construct
=========================================

In _most_ cases we can map this directly to '__thread'.  Except that OMP
allows constructors for C++ objects.  We can either refuse to support
this (how often is it used?)  or we can implement something akin to
.ctors.

   Even more ideally, this ctor feature is handled by extensions to the
main pthreads library.  Failing that, we can have a set of entry points
to register ctor functions to be called.


File: libgomp.info,  Node: Implementing PRIVATE clause,  Next: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Prev: Implementing THREADPRIVATE construct,  Up: The libgomp ABI

10.7 Implementing PRIVATE clause
================================

In association with a PARALLEL, or within the lexical extent of a
PARALLEL block, the variable becomes a local variable in the parallel
subfunction.

   In association with FOR or SECTIONS blocks, create a new automatic
variable within the current function.  This preserves the semantic of
new variable creation.


File: libgomp.info,  Node: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Next: Implementing REDUCTION clause,  Prev: Implementing PRIVATE clause,  Up: The libgomp ABI

10.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses
=========================================================================

This seems simple enough for PARALLEL blocks.  Create a private struct
for communicating between the parent and subfunction.  In the parent,
copy in values for scalar and "small" structs; copy in addresses for
others TREE_ADDRESSABLE types.  In the subfunction, copy the value into
the local variable.

   It is not clear what to do with bare FOR or SECTION blocks.  The only
thing I can figure is that we do something like:

     #pragma omp for firstprivate(x) lastprivate(y)
     for (int i = 0; i < n; ++i)
       body;

   which becomes

     {
       int x = x, y;

       // for stuff

       if (i == n)
         y = y;
     }

   where the "x=x" and "y=y" assignments actually have different uids
for the two variables, i.e.  not something you could write directly in
C. Presumably this only makes sense if the "outer" x and y are global
variables.

   COPYPRIVATE would work the same way, except the structure broadcast
would have to happen via SINGLE machinery instead.


File: libgomp.info,  Node: Implementing REDUCTION clause,  Next: Implementing PARALLEL construct,  Prev: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses,  Up: The libgomp ABI

10.9 Implementing REDUCTION clause
==================================

The private struct mentioned in the previous section should have a
pointer to an array of the type of the variable, indexed by the thread's
TEAM_ID.  The thread stores its final value into the array, and after
the barrier, the master thread iterates over the array to collect the
values.


File: libgomp.info,  Node: Implementing PARALLEL construct,  Next: Implementing FOR construct,  Prev: Implementing REDUCTION clause,  Up: The libgomp ABI

10.10 Implementing PARALLEL construct
=====================================

       #pragma omp parallel
       {
         body;
       }

   becomes

       void subfunction (void *data)
       {
         use data;
         body;
       }

       setup data;
       GOMP_parallel_start (subfunction, &data, num_threads);
       subfunction (&data);
       GOMP_parallel_end ();

       void GOMP_parallel_start (void (*fn)(void *), void *data, unsigned num_threads)

   The FN argument is the subfunction to be run in parallel.

   The DATA argument is a pointer to a structure used to communicate
data in and out of the subfunction, as discussed above with respect to
FIRSTPRIVATE et al.

   The NUM_THREADS argument is 1 if an IF clause is present and false,
or the value of the NUM_THREADS clause, if present, or 0.

   The function needs to create the appropriate number of threads and/or
launch them from the dock.  It needs to create the team structure and
assign team ids.

       void GOMP_parallel_end (void)

   Tears down the team and returns us to the previous
'omp_in_parallel()' state.


File: libgomp.info,  Node: Implementing FOR construct,  Next: Implementing ORDERED construct,  Prev: Implementing PARALLEL construct,  Up: The libgomp ABI

10.11 Implementing FOR construct
================================

       #pragma omp parallel for
       for (i = lb; i <= ub; i++)
         body;

   becomes

       void subfunction (void *data)
       {
         long _s0, _e0;
         while (GOMP_loop_static_next (&_s0, &_e0))
         {
           long _e1 = _e0, i;
           for (i = _s0; i < _e1; i++)
             body;
         }
         GOMP_loop_end_nowait ();
       }

       GOMP_parallel_loop_static (subfunction, NULL, 0, lb, ub+1, 1, 0);
       subfunction (NULL);
       GOMP_parallel_end ();

       #pragma omp for schedule(runtime)
       for (i = 0; i < n; i++)
         body;

   becomes

       {
         long i, _s0, _e0;
         if (GOMP_loop_runtime_start (0, n, 1, &_s0, &_e0))
           do {
             long _e1 = _e0;
             for (i = _s0, i < _e0; i++)
               body;
           } while (GOMP_loop_runtime_next (&_s0, _&e0));
         GOMP_loop_end ();
       }

   Note that while it looks like there is trickiness to propagating a
non-constant STEP, there isn't really.  We're explicitly allowed to
evaluate it as many times as we want, and any variables involved should
automatically be handled as PRIVATE or SHARED like any other variables.
So the expression should remain evaluable in the subfunction.  We can
also pull it into a local variable if we like, but since its supposed to
remain unchanged, we can also not if we like.

   If we have SCHEDULE(STATIC), and no ORDERED, then we ought to be able
to get away with no work-sharing context at all, since we can simply
perform the arithmetic directly in each thread to divide up the
iterations.  Which would mean that we wouldn't need to call any of these
routines.

   There are separate routines for handling loops with an ORDERED
clause.  Bookkeeping for that is non-trivial...


File: libgomp.info,  Node: Implementing ORDERED construct,  Next: Implementing SECTIONS construct,  Prev: Implementing FOR construct,  Up: The libgomp ABI

10.12 Implementing ORDERED construct
====================================

       void GOMP_ordered_start (void)
       void GOMP_ordered_end (void)


File: libgomp.info,  Node: Implementing SECTIONS construct,  Next: Implementing SINGLE construct,  Prev: Implementing ORDERED construct,  Up: The libgomp ABI

10.13 Implementing SECTIONS construct
=====================================

A block as

       #pragma omp sections
       {
         #pragma omp section
         stmt1;
         #pragma omp section
         stmt2;
         #pragma omp section
         stmt3;
       }

   becomes

       for (i = GOMP_sections_start (3); i != 0; i = GOMP_sections_next ())
         switch (i)
           {
           case 1:
             stmt1;
             break;
           case 2:
             stmt2;
             break;
           case 3:
             stmt3;
             break;
           }
       GOMP_barrier ();


File: libgomp.info,  Node: Implementing SINGLE construct,  Next: Implementing OpenACC's PARALLEL construct,  Prev: Implementing SECTIONS construct,  Up: The libgomp ABI

10.14 Implementing SINGLE construct
===================================

A block like

       #pragma omp single
       {
         body;
       }

   becomes

       if (GOMP_single_start ())
         body;
       GOMP_barrier ();

   while

       #pragma omp single copyprivate(x)
         body;

   becomes

       datap = GOMP_single_copy_start ();
       if (datap == NULL)
         {
           body;
           data.x = x;
           GOMP_single_copy_end (&data);
         }
       else
         x = datap->x;
       GOMP_barrier ();


File: libgomp.info,  Node: Implementing OpenACC's PARALLEL construct,  Prev: Implementing SINGLE construct,  Up: The libgomp ABI

10.15 Implementing OpenACC's PARALLEL construct
===============================================

       void GOACC_parallel ()


File: libgomp.info,  Node: Reporting Bugs,  Next: Copying,  Prev: The libgomp ABI,  Up: Top

11 Reporting Bugs
*****************

Bugs in the GNU Offloading and Multi Processing Runtime Library should
be reported via Bugzilla (https://gcc.gnu.org/bugzilla/).  Please add
"openacc", or "openmp", or both to the keywords field in the bug report,
as appropriate.


File: libgomp.info,  Node: Copying,  Next: GNU Free Documentation License,  Prev: Reporting Bugs,  Up: Top

GNU General Public License
**************************

                        Version 3, 29 June 2007

     Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>

     Everyone is permitted to copy and distribute verbatim copies of this
     license document, but changing it is not allowed.

Preamble
========

The GNU General Public License is a free, copyleft license for software
and other kinds of works.

   The licenses for most software and other practical works are designed
to take away your freedom to share and change the works.  By contrast,
the GNU General Public License is intended to guarantee your freedom to
share and change all versions of a program-to make sure it remains free
software for all its users.  We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors.  You can apply it to
your programs, too.

   When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
them if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new
free programs, and that you know you can do these things.

   To protect your rights, we need to prevent others from denying you
these rights or asking you to surrender the rights.  Therefore, you have
certain responsibilities if you distribute copies of the software, or if
you modify it: responsibilities to respect the freedom of others.

   For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
freedoms that you received.  You must make sure that they, too, receive
or can get the source code.  And you must show them these terms so they
know their rights.

   Developers that use the GNU GPL protect your rights with two steps:
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.

   For the developers' and authors' protection, the GPL clearly explains
that there is no warranty for this free software.  For both users' and
authors' sake, the GPL requires that modified versions be marked as
changed, so that their problems will not be attributed erroneously to
authors of previous versions.

   Some devices are designed to deny users access to install or run
modified versions of the software inside them, although the manufacturer
can do so.  This is fundamentally incompatible with the aim of
protecting users' freedom to change the software.  The systematic
pattern of such abuse occurs in the area of products for individuals to
use, which is precisely where it is most unacceptable.  Therefore, we
have designed this version of the GPL to prohibit the practice for those
products.  If such problems arise substantially in other domains, we
stand ready to extend this provision to those domains in future versions
of the GPL, as needed to protect the freedom of users.

   Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
software on general-purpose computers, but in those that do, we wish to
avoid the special danger that patents applied to a free program could
make it effectively proprietary.  To prevent this, the GPL assures that
patents cannot be used to render the program non-free.

   The precise terms and conditions for copying, distribution and
modification follow.

TERMS AND CONDITIONS
====================

  0. Definitions.

     "This License" refers to version 3 of the GNU General Public
     License.

     "Copyright" also means copyright-like laws that apply to other
     kinds of works, such as semiconductor masks.

     "The Program" refers to any copyrightable work licensed under this
     License.  Each licensee is addressed as "you".  "Licensees" and
     "recipients" may be individuals or organizations.

     To "modify" a work means to copy from or adapt all or part of the
     work in a fashion requiring copyright permission, other than the
     making of an exact copy.  The resulting work is called a "modified
     version" of the earlier work or a work "based on" the earlier work.

     A "covered work" means either the unmodified Program or a work
     based on the Program.

     To "propagate" a work means to do anything with it that, without
     permission, would make you directly or secondarily liable for
     infringement under applicable copyright law, except executing it on
     a computer or modifying a private copy.  Propagation includes
     copying, distribution (with or without modification), making
     available to the public, and in some countries other activities as
     well.

     To "convey" a work means any kind of propagation that enables other
     parties to make or receive copies.  Mere interaction with a user
     through a computer network, with no transfer of a copy, is not
     conveying.

     An interactive user interface displays "Appropriate Legal Notices"
     to the extent that it includes a convenient and prominently visible
     feature that (1) displays an appropriate copyright notice, and (2)
     tells the user that there is no warranty for the work (except to
     the extent that warranties are provided), that licensees may convey
     the work under this License, and how to view a copy of this
     License.  If the interface presents a list of user commands or
     options, such as a menu, a prominent item in the list meets this
     criterion.

  1. Source Code.

     The "source code" for a work means the preferred form of the work
     for making modifications to it.  "Object code" means any non-source
     form of a work.

     A "Standard Interface" means an interface that either is an
     official standard defined by a recognized standards body, or, in
     the case of interfaces specified for a particular programming
     language, one that is widely used among developers working in that
     language.

     The "System Libraries" of an executable work include anything,
     other than the work as a whole, that (a) is included in the normal
     form of packaging a Major Component, but which is not part of that
     Major Component, and (b) serves only to enable use of the work with
     that Major Component, or to implement a Standard Interface for
     which an implementation is available to the public in source code
     form.  A "Major Component", in this context, means a major
     essential component (kernel, window system, and so on) of the
     specific operating system (if any) on which the executable work
     runs, or a compiler used to produce the work, or an object code
     interpreter used to run it.

     The "Corresponding Source" for a work in object code form means all
     the source code needed to generate, install, and (for an executable
     work) run the object code and to modify the work, including scripts
     to control those activities.  However, it does not include the
     work's System Libraries, or general-purpose tools or generally
     available free programs which are used unmodified in performing
     those activities but which are not part of the work.  For example,
     Corresponding Source includes interface definition files associated
     with source files for the work, and the source code for shared
     libraries and dynamically linked subprograms that the work is
     specifically designed to require, such as by intimate data
     communication or control flow between those subprograms and other
     parts of the work.

     The Corresponding Source need not include anything that users can
     regenerate automatically from other parts of the Corresponding
     Source.

     The Corresponding Source for a work in source code form is that
     same work.

  2. Basic Permissions.

     All rights granted under this License are granted for the term of
     copyright on the Program, and are irrevocable provided the stated
     conditions are met.  This License explicitly affirms your unlimited
     permission to run the unmodified Program.  The output from running
     a covered work is covered by this License only if the output, given
     its content, constitutes a covered work.  This License acknowledges
     your rights of fair use or other equivalent, as provided by
     copyright law.

     You may make, run and propagate covered works that you do not
     convey, without conditions so long as your license otherwise
     remains in force.  You may convey covered works to others for the
     sole purpose of having them make modifications exclusively for you,
     or provide you with facilities for running those works, provided
     that you comply with the terms of this License in conveying all
     material for which you do not control copyright.  Those thus making
     or running the covered works for you must do so exclusively on your
     behalf, under your direction and control, on terms that prohibit
     them from making any copies of your copyrighted material outside
     their relationship with you.

     Conveying under any other circumstances is permitted solely under
     the conditions stated below.  Sublicensing is not allowed; section
     10 makes it unnecessary.

  3. Protecting Users' Legal Rights From Anti-Circumvention Law.

     No covered work shall be deemed part of an effective technological
     measure under any applicable law fulfilling obligations under
     article 11 of the WIPO copyright treaty adopted on 20 December
     1996, or similar laws prohibiting or restricting circumvention of
     such measures.

     When you convey a covered work, you waive any legal power to forbid
     circumvention of technological measures to the extent such
     circumvention is effected by exercising rights under this License
     with respect to the covered work, and you disclaim any intention to
     limit operation or modification of the work as a means of
     enforcing, against the work's users, your or third parties' legal
     rights to forbid circumvention of technological measures.

  4. Conveying Verbatim Copies.

     You may convey verbatim copies of the Program's source code as you
     receive it, in any medium, provided that you conspicuously and
     appropriately publish on each copy an appropriate copyright notice;
     keep intact all notices stating that this License and any
     non-permissive terms added in accord with section 7 apply to the
     code; keep intact all notices of the absence of any warranty; and
     give all recipients a copy of this License along with the Program.

     You may charge any price or no price for each copy that you convey,
     and you may offer support or warranty protection for a fee.

  5. Conveying Modified Source Versions.

     You may convey a work based on the Program, or the modifications to
     produce it from the Program, in the form of source code under the
     terms of section 4, provided that you also meet all of these
     conditions:

       a. The work must carry prominent notices stating that you
          modified it, and giving a relevant date.

       b. The work must carry prominent notices stating that it is
          released under this License and any conditions added under
          section 7.  This requirement modifies the requirement in
          section 4 to "keep intact all notices".

       c. You must license the entire work, as a whole, under this
          License to anyone who comes into possession of a copy.  This
          License will therefore apply, along with any applicable
          section 7 additional terms, to the whole of the work, and all
          its parts, regardless of how they are packaged.  This License
          gives no permission to license the work in any other way, but
          it does not invalidate such permission if you have separately
          received it.

       d. If the work has interactive user interfaces, each must display
          Appropriate Legal Notices; however, if the Program has
          interactive interfaces that do not display Appropriate Legal
          Notices, your work need not make them do so.

     A compilation of a covered work with other separate and independent
     works, which are not by their nature extensions of the covered
     work, and which are not combined with it such as to form a larger
     program, in or on a volume of a storage or distribution medium, is
     called an "aggregate" if the compilation and its resulting
     copyright are not used to limit the access or legal rights of the
     compilation's users beyond what the individual works permit.
     Inclusion of a covered work in an aggregate does not cause this
     License to apply to the other parts of the aggregate.

  6. Conveying Non-Source Forms.

     You may convey a covered work in object code form under the terms
     of sections 4 and 5, provided that you also convey the
     machine-readable Corresponding Source under the terms of this
     License, in one of these ways:

       a. Convey the object code in, or embodied in, a physical product
          (including a physical distribution medium), accompanied by the
          Corresponding Source fixed on a durable physical medium
          customarily used for software interchange.

       b. Convey the object code in, or embodied in, a physical product
          (including a physical distribution medium), accompanied by a
          written offer, valid for at least three years and valid for as
          long as you offer spare parts or customer support for that
          product model, to give anyone who possesses the object code
          either (1) a copy of the Corresponding Source for all the
          software in the product that is covered by this License, on a
          durable physical medium customarily used for software
          interchange, for a price no more than your reasonable cost of
          physically performing this conveying of source, or (2) access
          to copy the Corresponding Source from a network server at no
          charge.

       c. Convey individual copies of the object code with a copy of the
          written offer to provide the Corresponding Source.  This
          alternative is allowed only occasionally and noncommercially,
          and only if you received the object code with such an offer,
          in accord with subsection 6b.

       d. Convey the object code by offering access from a designated
          place (gratis or for a charge), and offer equivalent access to
          the Corresponding Source in the same way through the same
          place at no further charge.  You need not require recipients
          to copy the Corresponding Source along with the object code.
          If the place to copy the object code is a network server, the
          Corresponding Source may be on a different server (operated by
          you or a third party) that supports equivalent copying
          facilities, provided you maintain clear directions next to the
          object code saying where to find the Corresponding Source.
          Regardless of what server hosts the Corresponding Source, you
          remain obligated to ensure that it is available for as long as
          needed to satisfy these requirements.

       e. Convey the object code using peer-to-peer transmission,
          provided you inform other peers where the object code and
          Corresponding Source of the work are being offered to the
          general public at no charge under subsection 6d.

     A separable portion of the object code, whose source code is
     excluded from the Corresponding Source as a System Library, need
     not be included in conveying the object code work.

     A "User Product" is either (1) a "consumer product", which means
     any tangible personal property which is normally used for personal,
     family, or household purposes, or (2) anything designed or sold for
     incorporation into a dwelling.  In determining whether a product is
     a consumer product, doubtful cases shall be resolved in favor of
     coverage.  For a particular product received by a particular user,
     "normally used" refers to a typical or common use of that class of
     product, regardless of the status of the particular user or of the
     way in which the particular user actually uses, or expects or is
     expected to use, the product.  A product is a consumer product
     regardless of whether the product has substantial commercial,
     industrial or non-consumer uses, unless such uses represent the
     only significant mode of use of the product.

     "Installation Information" for a User Product means any methods,
     procedures, authorization keys, or other information required to
     install and execute modified versions of a covered work in that
     User Product from a modified version of its Corresponding Source.
     The information must suffice to ensure that the continued
     functioning of the modified object code is in no case prevented or
     interfered with solely because modification has been made.

     If you convey an object code work under this section in, or with,
     or specifically for use in, a User Product, and the conveying
     occurs as part of a transaction in which the right of possession
     and use of the User Product is transferred to the recipient in
     perpetuity or for a fixed term (regardless of how the transaction
     is characterized), the Corresponding Source conveyed under this
     section must be accompanied by the Installation Information.  But
     this requirement does not apply if neither you nor any third party
     retains the ability to install modified object code on the User
     Product (for example, the work has been installed in ROM).

     The requirement to provide Installation Information does not
     include a requirement to continue to provide support service,
     warranty, or updates for a work that has been modified or installed
     by the recipient, or for the User Product in which it has been
     modified or installed.  Access to a network may be denied when the
     modification itself materially and adversely affects the operation
     of the network or violates the rules and protocols for
     communication across the network.

     Corresponding Source conveyed, and Installation Information
     provided, in accord with this section must be in a format that is
     publicly documented (and with an implementation available to the
     public in source code form), and must require no special password
     or key for unpacking, reading or copying.

  7. Additional Terms.

     "Additional permissions" are terms that supplement the terms of
     this License by making exceptions from one or more of its
     conditions.  Additional permissions that are applicable to the
     entire Program shall be treated as though they were included in
     this License, to the extent that they are valid under applicable
     law.  If additional permissions apply only to part of the Program,
     that part may be used separately under those permissions, but the
     entire Program remains governed by this License without regard to
     the additional permissions.

     When you convey a copy of a covered work, you may at your option
     remove any additional permissions from that copy, or from any part
     of it.  (Additional permissions may be written to require their own
     removal in certain cases when you modify the work.)  You may place
     additional permissions on material, added by you to a covered work,
     for which you have or can give appropriate copyright permission.

     Notwithstanding any other provision of this License, for material
     you add to a covered work, you may (if authorized by the copyright
     holders of that material) supplement the terms of this License with
     terms:

       a. Disclaiming warranty or limiting liability differently from
          the terms of sections 15 and 16 of this License; or

       b. Requiring preservation of specified reasonable legal notices
          or author attributions in that material or in the Appropriate
          Legal Notices displayed by works containing it; or

       c. Prohibiting misrepresentation of the origin of that material,
          or requiring that modified versions of such material be marked
          in reasonable ways as different from the original version; or

       d. Limiting the use for publicity purposes of names of licensors
          or authors of the material; or

       e. Declining to grant rights under trademark law for use of some
          trade names, trademarks, or service marks; or

       f. Requiring indemnification of licensors and authors of that
          material by anyone who conveys the material (or modified
          versions of it) with contractual assumptions of liability to
          the recipient, for any liability that these contractual
          assumptions directly impose on those licensors and authors.

     All other non-permissive additional terms are considered "further
     restrictions" within the meaning of section 10.  If the Program as
     you received it, or any part of it, contains a notice stating that
     it is governed by this License along with a term that is a further
     restriction, you may remove that term.  If a license document
     contains a further restriction but permits relicensing or conveying
     under this License, you may add to a covered work material governed
     by the terms of that license document, provided that the further
     restriction does not survive such relicensing or conveying.

     If you add terms to a covered work in accord with this section, you
     must place, in the relevant source files, a statement of the
     additional terms that apply to those files, or a notice indicating
     where to find the applicable terms.

     Additional terms, permissive or non-permissive, may be stated in
     the form of a separately written license, or stated as exceptions;
     the above requirements apply either way.

  8. Termination.

     You may not propagate or modify a covered work except as expressly
     provided under this License.  Any attempt otherwise to propagate or
     modify it is void, and will automatically terminate your rights
     under this License (including any patent licenses granted under the
     third paragraph of section 11).

     However, if you cease all violation of this License, then your
     license from a particular copyright holder is reinstated (a)
     provisionally, unless and until the copyright holder explicitly and
     finally terminates your license, and (b) permanently, if the
     copyright holder fails to notify you of the violation by some
     reasonable means prior to 60 days after the cessation.

     Moreover, your license from a particular copyright holder is
     reinstated permanently if the copyright holder notifies you of the
     violation by some reasonable means, this is the first time you have
     received notice of violation of this License (for any work) from
     that copyright holder, and you cure the violation prior to 30 days
     after your receipt of the notice.

     Termination of your rights under this section does not terminate
     the licenses of parties who have received copies or rights from you
     under this License.  If your rights have been terminated and not
     permanently reinstated, you do not qualify to receive new licenses
     for the same material under section 10.

  9. Acceptance Not Required for Having Copies.

     You are not required to accept this License in order to receive or
     run a copy of the Program.  Ancillary propagation of a covered work
     occurring solely as a consequence of using peer-to-peer
     transmission to receive a copy likewise does not require
     acceptance.  However, nothing other than this License grants you
     permission to propagate or modify any covered work.  These actions
     infringe copyright if you do not accept this License.  Therefore,
     by modifying or propagating a covered work, you indicate your
     acceptance of this License to do so.

  10. Automatic Licensing of Downstream Recipients.

     Each time you convey a covered work, the recipient automatically
     receives a license from the original licensors, to run, modify and
     propagate that work, subject to this License.  You are not
     responsible for enforcing compliance by third parties with this
     License.

     An "entity transaction" is a transaction transferring control of an
     organization, or substantially all assets of one, or subdividing an
     organization, or merging organizations.  If propagation of a
     covered work results from an entity transaction, each party to that
     transaction who receives a copy of the work also receives whatever
     licenses to the work the party's predecessor in interest had or
     could give under the previous paragraph, plus a right to possession
     of the Corresponding Source of the work from the predecessor in
     interest, if the predecessor has it or can get it with reasonable
     efforts.

     You may not impose any further restrictions on the exercise of the
     rights granted or affirmed under this License.  For example, you
     may not impose a license fee, royalty, or other charge for exercise
     of rights granted under this License, and you may not initiate
     litigation (including a cross-claim or counterclaim in a lawsuit)
     alleging that any patent claim is infringed by making, using,
     selling, offering for sale, or importing the Program or any portion
     of it.

  11. Patents.

     A "contributor" is a copyright holder who authorizes use under this
     License of the Program or a work on which the Program is based.
     The work thus licensed is called the contributor's "contributor
     version".

     A contributor's "essential patent claims" are all patent claims
     owned or controlled by the contributor, whether already acquired or
     hereafter acquired, that would be infringed by some manner,
     permitted by this License, of making, using, or selling its
     contributor version, but do not include claims that would be
     infringed only as a consequence of further modification of the
     contributor version.  For purposes of this definition, "control"
     includes the right to grant patent sublicenses in a manner
     consistent with the requirements of this License.

     Each contributor grants you a non-exclusive, worldwide,
     royalty-free patent license under the contributor's essential
     patent claims, to make, use, sell, offer for sale, import and
     otherwise run, modify and propagate the contents of its contributor
     version.

     In the following three paragraphs, a "patent license" is any
     express agreement or commitment, however denominated, not to
     enforce a patent (such as an express permission to practice a
     patent or covenant not to sue for patent infringement).  To "grant"
     such a patent license to a party means to make such an agreement or
     commitment not to enforce a patent against the party.

     If you convey a covered work, knowingly relying on a patent
     license, and the Corresponding Source of the work is not available
     for anyone to copy, free of charge and under the terms of this
     License, through a publicly available network server or other
     readily accessible means, then you must either (1) cause the
     Corresponding Source to be so available, or (2) arrange to deprive
     yourself of the benefit of the patent license for this particular
     work, or (3) arrange, in a manner consistent with the requirements
     of this License, to extend the patent license to downstream
     recipients.  "Knowingly relying" means you have actual knowledge
     that, but for the patent license, your conveying the covered work
     in a country, or your recipient's use of the covered work in a
     country, would infringe one or more identifiable patents in that
     country that you have reason to believe are valid.

     If, pursuant to or in connection with a single transaction or
     arrangement, you convey, or propagate by procuring conveyance of, a
     covered work, and grant a patent license to some of the parties
     receiving the covered work authorizing them to use, propagate,
     modify or convey a specific copy of the covered work, then the
     patent license you grant is automatically extended to all
     recipients of the covered work and works based on it.

     A patent license is "discriminatory" if it does not include within
     the scope of its coverage, prohibits the exercise of, or is
     conditioned on the non-exercise of one or more of the rights that
     are specifically granted under this License.  You may not convey a
     covered work if you are a party to an arrangement with a third
     party that is in the business of distributing software, under which
     you make payment to the third party based on the extent of your
     activity of conveying the work, and under which the third party
     grants, to any of the parties who would receive the covered work
     from you, a discriminatory patent license (a) in connection with
     copies of the covered work conveyed by you (or copies made from
     those copies), or (b) primarily for and in connection with specific
     products or compilations that contain the covered work, unless you
     entered into that arrangement, or that patent license was granted,
     prior to 28 March 2007.

     Nothing in this License shall be construed as excluding or limiting
     any implied license or other defenses to infringement that may
     otherwise be available to you under applicable patent law.

  12. No Surrender of Others' Freedom.

     If conditions are imposed on you (whether by court order, agreement
     or otherwise) that contradict the conditions of this License, they
     do not excuse you from the conditions of this License.  If you
     cannot convey a covered work so as to satisfy simultaneously your
     obligations under this License and any other pertinent obligations,
     then as a consequence you may not convey it at all.  For example,
     if you agree to terms that obligate you to collect a royalty for
     further conveying from those to whom you convey the Program, the
     only way you could satisfy both those terms and this License would
     be to refrain entirely from conveying the Program.

  13. Use with the GNU Affero General Public License.

     Notwithstanding any other provision of this License, you have
     permission to link or combine any covered work with a work licensed
     under version 3 of the GNU Affero General Public License into a
     single combined work, and to convey the resulting work.  The terms
     of this License will continue to apply to the part which is the
     covered work, but the special requirements of the GNU Affero
     General Public License, section 13, concerning interaction through
     a network will apply to the combination as such.

  14. Revised Versions of this License.

     The Free Software Foundation may publish revised and/or new
     versions of the GNU General Public License from time to time.  Such
     new versions will be similar in spirit to the present version, but
     may differ in detail to address new problems or concerns.

     Each version is given a distinguishing version number.  If the
     Program specifies that a certain numbered version of the GNU
     General Public License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that numbered version or of any later version published by the Free
     Software Foundation.  If the Program does not specify a version
     number of the GNU General Public License, you may choose any
     version ever published by the Free Software Foundation.

     If the Program specifies that a proxy can decide which future
     versions of the GNU General Public License can be used, that
     proxy's public statement of acceptance of a version permanently
     authorizes you to choose that version for the Program.

     Later license versions may give you additional or different
     permissions.  However, no additional obligations are imposed on any
     author or copyright holder as a result of your choosing to follow a
     later version.

  15. Disclaimer of Warranty.

     THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
     APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
     COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
     WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
     RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.
     SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
     NECESSARY SERVICING, REPAIR OR CORRECTION.

  16. Limitation of Liability.

     IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
     WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES
     AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
     DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
     CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
     THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
     BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
     PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
     PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF
     THE POSSIBILITY OF SUCH DAMAGES.

  17. Interpretation of Sections 15 and 16.

     If the disclaimer of warranty and limitation of liability provided
     above cannot be given local legal effect according to their terms,
     reviewing courts shall apply local law that most closely
     approximates an absolute waiver of all civil liability in
     connection with the Program, unless a warranty or assumption of
     liability accompanies a copy of the Program in return for a fee.

END OF TERMS AND CONDITIONS
===========================

How to Apply These Terms to Your New Programs
=============================================

If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.

   To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least the
"copyright" line and a pointer to where the full notice is found.

     ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
     Copyright (C) YEAR NAME OF AUTHOR

     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation, either version 3 of the License, or (at
     your option) any later version.

     This program is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Also add information on how to contact you by electronic and paper
mail.

   If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

     PROGRAM Copyright (C) YEAR NAME OF AUTHOR
     This program comes with ABSOLUTELY NO WARRANTY; for details type 'show w'.
     This is free software, and you are welcome to redistribute it
     under certain conditions; type 'show c' for details.

   The hypothetical commands 'show w' and 'show c' should show the
appropriate parts of the General Public License.  Of course, your
program's commands might be different; for a GUI interface, you would
use an "about box".

   You should also get your employer (if you work as a programmer) or
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  For more information on this, and how to apply and follow
the GNU GPL, see <http://www.gnu.org/licenses/>.

   The GNU General Public License does not permit incorporating your
program into proprietary programs.  If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library.  If this is what you want to do, use the
GNU Lesser General Public License instead of this License.  But first,
please read <https://www.gnu.org/licenses/why-not-lgpl.html>.


File: libgomp.info,  Node: GNU Free Documentation License,  Next: Funding,  Prev: Copying,  Up: Top

GNU Free Documentation License
******************************

                     Version 1.3, 3 November 2008

     Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
     <http://fsf.org/>

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other
     functional and useful document "free" in the sense of freedom: to
     assure everyone the effective freedom to copy and redistribute it,
     with or without modifying it, either commercially or
     noncommercially.  Secondarily, this License preserves for the
     author and publisher a way to get credit for their work, while not
     being considered responsible for modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.  We
     recommend this License principally for works whose purpose is
     instruction or reference.

  1. APPLICABILITY AND DEFINITIONS

     This License applies to any manual or other work, in any medium,
     that contains a notice placed by the copyright holder saying it can
     be distributed under the terms of this License.  Such a notice
     grants a world-wide, royalty-free license, unlimited in duration,
     to use that work under the conditions stated herein.  The
     "Document", below, refers to any such manual or work.  Any member
     of the public is a licensee, and is addressed as "you".  You accept
     the license if you copy, modify or distribute the work in a way
     requiring permission under copyright law.

     A "Modified Version" of the Document means any work containing the
     Document or a portion of it, either copied verbatim, or with
     modifications and/or translated into another language.

     A "Secondary Section" is a named appendix or a front-matter section
     of the Document that deals exclusively with the relationship of the
     publishers or authors of the Document to the Document's overall
     subject (or to related matters) and contains nothing that could
     fall directly within that overall subject.  (Thus, if the Document
     is in part a textbook of mathematics, a Secondary Section may not
     explain any mathematics.)  The relationship could be a matter of
     historical connection with the subject or with related matters, or
     of legal, commercial, philosophical, ethical or political position
     regarding them.

     The "Invariant Sections" are certain Secondary Sections whose
     titles are designated, as being those of Invariant Sections, in the
     notice that says that the Document is released under this License.
     If a section does not fit the above definition of Secondary then it
     is not allowed to be designated as Invariant.  The Document may
     contain zero Invariant Sections.  If the Document does not identify
     any Invariant Sections then there are none.

     The "Cover Texts" are certain short passages of text that are
     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
     that says that the Document is released under this License.  A
     Front-Cover Text may be at most 5 words, and a Back-Cover Text may
     be at most 25 words.

     A "Transparent" copy of the Document means a machine-readable copy,
     represented in a format whose specification is available to the
     general public, that is suitable for revising the document
     straightforwardly with generic text editors or (for images composed
     of pixels) generic paint programs or (for drawings) some widely
     available drawing editor, and that is suitable for input to text
     formatters or for automatic translation to a variety of formats
     suitable for input to text formatters.  A copy made in an otherwise
     Transparent file format whose markup, or absence of markup, has
     been arranged to thwart or discourage subsequent modification by
     readers is not Transparent.  An image format is not Transparent if
     used for any substantial amount of text.  A copy that is not
     "Transparent" is called "Opaque".

     Examples of suitable formats for Transparent copies include plain
     ASCII without markup, Texinfo input format, LaTeX input format,
     SGML or XML using a publicly available DTD, and standard-conforming
     simple HTML, PostScript or PDF designed for human modification.
     Examples of transparent image formats include PNG, XCF and JPG.
     Opaque formats include proprietary formats that can be read and
     edited only by proprietary word processors, SGML or XML for which
     the DTD and/or processing tools are not generally available, and
     the machine-generated HTML, PostScript or PDF produced by some word
     processors for output purposes only.

     The "Title Page" means, for a printed book, the title page itself,
     plus such following pages as are needed to hold, legibly, the
     material this License requires to appear in the title page.  For
     works in formats which do not have any title page as such, "Title
     Page" means the text near the most prominent appearance of the
     work's title, preceding the beginning of the body of the text.

     The "publisher" means any person or entity that distributes copies
     of the Document to the public.

     A section "Entitled XYZ" means a named subunit of the Document
     whose title either is precisely XYZ or contains XYZ in parentheses
     following text that translates XYZ in another language.  (Here XYZ
     stands for a specific section name mentioned below, such as
     "Acknowledgements", "Dedications", "Endorsements", or "History".)
     To "Preserve the Title" of such a section when you modify the
     Document means that it remains a section "Entitled XYZ" according
     to this definition.

     The Document may include Warranty Disclaimers next to the notice
     which states that this License applies to the Document.  These
     Warranty Disclaimers are considered to be included by reference in
     this License, but only as regards disclaiming warranties: any other
     implication that these Warranty Disclaimers may have is void and
     has no effect on the meaning of this License.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow the
     conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies (or copies in media that commonly
     have printed covers) of the Document, numbering more than 100, and
     the Document's license notice requires Cover Texts, you must
     enclose the copies in covers that carry, clearly and legibly, all
     these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the title
     equally prominent and visible.  You may add other material on the
     covers in addition.  Copying with changes limited to the covers, as
     long as they preserve the title of the Document and satisfy these
     conditions, can be treated as verbatim copying in other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a machine-readable
     Transparent copy along with each Opaque copy, or state in or with
     each Opaque copy a computer-network location from which the general
     network-using public has access to download using public-standard
     network protocols a complete Transparent copy of the Document, free
     of added material.  If you use the latter option, you must take
     reasonably prudent steps, when you begin distribution of Opaque
     copies in quantity, to ensure that this Transparent copy will
     remain thus accessible at the stated location until at least one
     year after the last time you distribute an Opaque copy (directly or
     through your agents or retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of copies,
     to give them a chance to provide you with an updated version of the
     Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with the
     Modified Version filling the role of the Document, thus licensing
     distribution and modification of the Modified Version to whoever
     possesses a copy of it.  In addition, you must do these things in
     the Modified Version:

       A. Use in the Title Page (and on the covers, if any) a title
          distinct from that of the Document, and from those of previous
          versions (which should, if there were any, be listed in the
          History section of the Document).  You may use the same title
          as a previous version if the original publisher of that
          version gives permission.

       B. List on the Title Page, as authors, one or more persons or
          entities responsible for authorship of the modifications in
          the Modified Version, together with at least five of the
          principal authors of the Document (all of its principal
          authors, if it has fewer than five), unless they release you
          from this requirement.

       C. State on the Title page the name of the publisher of the
          Modified Version, as the publisher.

       D. Preserve all the copyright notices of the Document.

       E. Add an appropriate copyright notice for your modifications
          adjacent to the other copyright notices.

       F. Include, immediately after the copyright notices, a license
          notice giving the public permission to use the Modified
          Version under the terms of this License, in the form shown in
          the Addendum below.

       G. Preserve in that license notice the full lists of Invariant
          Sections and required Cover Texts given in the Document's
          license notice.

       H. Include an unaltered copy of this License.

       I. Preserve the section Entitled "History", Preserve its Title,
          and add to it an item stating at least the title, year, new
          authors, and publisher of the Modified Version as given on the
          Title Page.  If there is no section Entitled "History" in the
          Document, create one stating the title, year, authors, and
          publisher of the Document as given on its Title Page, then add
          an item describing the Modified Version as stated in the
          previous sentence.

       J. Preserve the network location, if any, given in the Document
          for public access to a Transparent copy of the Document, and
          likewise the network locations given in the Document for
          previous versions it was based on.  These may be placed in the
          "History" section.  You may omit a network location for a work
          that was published at least four years before the Document
          itself, or if the original publisher of the version it refers
          to gives permission.

       K. For any section Entitled "Acknowledgements" or "Dedications",
          Preserve the Title of the section, and preserve in the section
          all the substance and tone of each of the contributor
          acknowledgements and/or dedications given therein.

       L. Preserve all the Invariant Sections of the Document, unaltered
          in their text and in their titles.  Section numbers or the
          equivalent are not considered part of the section titles.

       M. Delete any section Entitled "Endorsements".  Such a section
          may not be included in the Modified Version.

       N. Do not retitle any existing section to be Entitled
          "Endorsements" or to conflict in title with any Invariant
          Section.

       O. Preserve any Warranty Disclaimers.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option designate
     some or all of these sections as invariant.  To do this, add their
     titles to the list of Invariant Sections in the Modified Version's
     license notice.  These titles must be distinct from any other
     section titles.

     You may add a section Entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties--for example, statements of peer review or that the text
     has been approved by an organization as the authoritative
     definition of a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end of
     the list of Cover Texts in the Modified Version.  Only one passage
     of Front-Cover Text and one of Back-Cover Text may be added by (or
     through arrangements made by) any one entity.  If the Document
     already includes a cover text for the same cover, previously added
     by you or by arrangement made by the same entity you are acting on
     behalf of, you may not add another; but you may replace the old
     one, on explicit permission from the previous publisher that added
     the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination all
     of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice, and that you preserve all
     their Warranty Disclaimers.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections Entitled
     "History" in the various original documents, forming one section
     Entitled "History"; likewise combine any sections Entitled
     "Acknowledgements", and any sections Entitled "Dedications".  You
     must delete all sections Entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the documents
     in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow this
     License in all other respects regarding verbatim copying of that
     document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of a
     storage or distribution medium, is called an "aggregate" if the
     copyright resulting from the compilation is not used to limit the
     legal rights of the compilation's users beyond what the individual
     works permit.  When the Document is included in an aggregate, this
     License does not apply to the other works in the aggregate which
     are not themselves derivative works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one half
     of the entire aggregate, the Document's Cover Texts may be placed
     on covers that bracket the Document within the aggregate, or the
     electronic equivalent of covers if the Document is in electronic
     form.  Otherwise they must appear on printed covers that bracket
     the whole aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License, and all the license notices in the
     Document, and any Warranty Disclaimers, provided that you also
     include the original English version of this License and the
     original versions of those notices and disclaimers.  In case of a
     disagreement between the translation and the original version of
     this License or a notice or disclaimer, the original version will
     prevail.

     If a section in the Document is Entitled "Acknowledgements",
     "Dedications", or "History", the requirement (section 4) to
     Preserve its Title (section 1) will typically require changing the
     actual title.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided under this License.  Any attempt
     otherwise to copy, modify, sublicense, or distribute it is void,
     and will automatically terminate your rights under this License.

     However, if you cease all violation of this License, then your
     license from a particular copyright holder is reinstated (a)
     provisionally, unless and until the copyright holder explicitly and
     finally terminates your license, and (b) permanently, if the
     copyright holder fails to notify you of the violation by some
     reasonable means prior to 60 days after the cessation.

     Moreover, your license from a particular copyright holder is
     reinstated permanently if the copyright holder notifies you of the
     violation by some reasonable means, this is the first time you have
     received notice of violation of this License (for any work) from
     that copyright holder, and you cure the violation prior to 30 days
     after your receipt of the notice.

     Termination of your rights under this section does not terminate
     the licenses of parties who have received copies or rights from you
     under this License.  If your rights have been terminated and not
     permanently reinstated, receipt of a copy of some or all of the
     same material does not give you any rights to use it.

  10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     <http://www.gnu.org/copyleft/>.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If the
     Document does not specify a version number of this License, you may
     choose any version ever published (not as a draft) by the Free
     Software Foundation.  If the Document specifies that a proxy can
     decide which future versions of this License can be used, that
     proxy's public statement of acceptance of a version permanently
     authorizes you to choose that version for the Document.

  11. RELICENSING

     "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
     World Wide Web server that publishes copyrightable works and also
     provides prominent facilities for anybody to edit those works.  A
     public wiki that anybody can edit is an example of such a server.
     A "Massive Multiauthor Collaboration" (or "MMC") contained in the
     site means any set of copyrightable works thus published on the MMC
     site.

     "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
     license published by Creative Commons Corporation, a not-for-profit
     corporation with a principal place of business in San Francisco,
     California, as well as future copyleft versions of that license
     published by that same organization.

     "Incorporate" means to publish or republish a Document, in whole or
     in part, as part of another Document.

     An MMC is "eligible for relicensing" if it is licensed under this
     License, and if all works that were first published under this
     License somewhere other than this MMC, and subsequently
     incorporated in whole or in part into the MMC, (1) had no cover
     texts or invariant sections, and (2) were thus incorporated prior
     to November 1, 2008.

     The operator of an MMC Site may republish an MMC contained in the
     site under CC-BY-SA on the same site at any time before August 1,
     2009, provided the MMC is eligible for relicensing.

ADDENDUM: How to use this License for your documents
====================================================

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

       Copyright (C)  YEAR  YOUR NAME.
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3
       or any later version published by the Free Software Foundation;
       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
       Texts.  A copy of the license is included in the section entitled ``GNU
       Free Documentation License''.

   If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts."  line with this:

         with the Invariant Sections being LIST THEIR TITLES, with
         the Front-Cover Texts being LIST, and with the Back-Cover Texts
         being LIST.

   If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.


File: libgomp.info,  Node: Funding,  Next: Library Index,  Prev: GNU Free Documentation License,  Up: Top

Funding Free Software
*********************

If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development.  The most effective approach known is to encourage
commercial redistributors to donate.

   Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers--the Free Software Foundation, and others.

   The way to convince distributors to do this is to demand it and
expect it from them.  So when you compare distributors, judge them
partly by how much they give to free software development.  Show
distributors they must compete to be the one who gives the most.

   To make this approach work, you must insist on numbers that you can
compare, such as, "We will donate ten dollars to the Frobnitz project
for each disk sold."  Don't be satisfied with a vague promise, such as
"A portion of the profits are donated," since it doesn't give a basis
for comparison.

   Even a precise fraction "of the profits from this disk" is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.  If
the price you pay is $50, ten percent of the profit is probably less
than a dollar; it might be a few cents, or nothing at all.

   Some redistributors do development work themselves.  This is useful
too; but to keep everyone honest, you need to inquire how much they do,
and what kind.  Some kinds of development make much more long-term
difference than others.  For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much.  Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU Compiler Collection contribute
more; major new features or packages contribute the most.

   By establishing the idea that supporting further development is "the
proper thing to do" when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.

     Copyright (C) 1994 Free Software Foundation, Inc.
     Verbatim copying and redistribution of this section is permitted
     without royalty; alteration is not permitted.


File: libgomp.info,  Node: Library Index,  Prev: Funding,  Up: Top

Library Index
*************

[index]
* Menu:

* acc_get_property:                      acc_get_property.      (line 6)
* acc_get_property_string:               acc_get_property.      (line 6)
* Environment Variable:                  OMP_CANCELLATION.      (line 6)
* Environment Variable <1>:              OMP_DISPLAY_ENV.       (line 6)
* Environment Variable <2>:              OMP_DEFAULT_DEVICE.    (line 6)
* Environment Variable <3>:              OMP_DYNAMIC.           (line 6)
* Environment Variable <4>:              OMP_MAX_ACTIVE_LEVELS. (line 6)
* Environment Variable <5>:              OMP_MAX_TASK_PRIORITY. (line 6)
* Environment Variable <6>:              OMP_NESTED.            (line 6)
* Environment Variable <7>:              OMP_NUM_THREADS.       (line 6)
* Environment Variable <8>:              OMP_PROC_BIND.         (line 6)
* Environment Variable <9>:              OMP_PLACES.            (line 6)
* Environment Variable <10>:             OMP_STACKSIZE.         (line 6)
* Environment Variable <11>:             OMP_SCHEDULE.          (line 6)
* Environment Variable <12>:             OMP_TARGET_OFFLOAD.    (line 6)
* Environment Variable <13>:             OMP_THREAD_LIMIT.      (line 6)
* Environment Variable <14>:             OMP_WAIT_POLICY.       (line 6)
* Environment Variable <15>:             GOMP_CPU_AFFINITY.     (line 6)
* Environment Variable <16>:             GOMP_DEBUG.            (line 6)
* Environment Variable <17>:             GOMP_STACKSIZE.        (line 6)
* Environment Variable <18>:             GOMP_SPINCOUNT.        (line 6)
* Environment Variable <19>:             GOMP_RTEMS_THREAD_POOLS.
                                                                (line 6)
* FDL, GNU Free Documentation License:   GNU Free Documentation License.
                                                                (line 6)
* Implementation specific setting:       OMP_NESTED.            (line 6)
* Implementation specific setting <1>:   OMP_NUM_THREADS.       (line 6)
* Implementation specific setting <2>:   OMP_SCHEDULE.          (line 6)
* Implementation specific setting <3>:   OMP_TARGET_OFFLOAD.    (line 6)
* Implementation specific setting <4>:   GOMP_STACKSIZE.        (line 6)
* Implementation specific setting <5>:   GOMP_SPINCOUNT.        (line 6)
* Implementation specific setting <6>:   GOMP_RTEMS_THREAD_POOLS.
                                                                (line 6)
* Introduction:                          Top.                   (line 6)



Tag Table:
Node: Top2083
Node: Enabling OpenMP4645
Node: Runtime Library Routines5421
Node: omp_get_active_level8741
Node: omp_get_ancestor_thread_num9441
Node: omp_get_cancellation10371
Node: omp_get_default_device11185
Node: omp_get_dynamic11861
Node: omp_get_initial_device12745
Node: omp_get_level13489
Node: omp_get_max_active_levels14116
Node: omp_get_max_task_priority14837
Node: omp_get_max_threads15457
Node: omp_get_nested16216
Node: omp_get_num_devices17824
Node: omp_get_num_procs18345
Node: omp_get_num_teams18884
Node: omp_get_num_threads19400
Node: omp_get_proc_bind20489
Node: omp_get_schedule21410
Node: omp_get_supported_active_levels22379
Node: omp_get_team_num23165
Node: omp_get_team_size23679
Node: omp_get_thread_limit24639
Node: omp_get_thread_num25258
Node: omp_in_parallel26129
Node: omp_in_final26778
Node: omp_is_initial_device27452
Node: omp_set_default_device28145
Node: omp_set_dynamic28936
Node: omp_set_max_active_levels29822
Node: omp_set_nested30744
Node: omp_set_num_threads31941
Node: omp_set_schedule32809
Node: omp_init_lock33890
Node: omp_set_lock34543
Node: omp_test_lock35398
Node: omp_unset_lock36374
Node: omp_destroy_lock37305
Node: omp_init_nest_lock37982
Node: omp_set_nest_lock38717
Node: omp_test_nest_lock39632
Node: omp_unset_nest_lock40659
Node: omp_destroy_nest_lock41674
Node: omp_get_wtick42425
Node: omp_get_wtime43017
Node: omp_fulfill_event43819
Node: Environment Variables44840
Node: OMP_CANCELLATION46467
Node: OMP_DISPLAY_ENV47000
Node: OMP_DEFAULT_DEVICE47703
Node: OMP_DYNAMIC48483
Node: OMP_MAX_ACTIVE_LEVELS49079
Node: OMP_MAX_TASK_PRIORITY50006
Node: OMP_NESTED50664
Node: OMP_NUM_THREADS51693
Node: OMP_PROC_BIND52495
Node: OMP_PLACES53806
Node: OMP_STACKSIZE55983
Node: OMP_SCHEDULE56807
Node: OMP_TARGET_OFFLOAD57507
Node: OMP_THREAD_LIMIT58463
Node: OMP_WAIT_POLICY59069
Node: GOMP_CPU_AFFINITY59761
Node: GOMP_DEBUG61491
Node: GOMP_STACKSIZE61998
Node: GOMP_SPINCOUNT62829
Node: GOMP_RTEMS_THREAD_POOLS64033
Node: Enabling OpenACC66211
Node: OpenACC Runtime Library Routines67112
Node: acc_get_num_devices71393
Node: acc_set_device_type72119
Node: acc_get_device_type72883
Node: acc_set_device_num73896
Node: acc_get_device_num74713
Node: acc_get_property75512
Node: acc_async_test77735
Node: acc_async_test_all78723
Node: acc_wait79623
Node: acc_wait_all80486
Node: acc_wait_all_async81247
Node: acc_wait_async81999
Node: acc_init82707
Node: acc_shutdown83352
Node: acc_on_device84019
Node: acc_malloc85023
Node: acc_free85522
Node: acc_copyin85949
Node: acc_present_or_copyin87536
Node: acc_create89314
Node: acc_present_or_create90946
Node: acc_copyout92732
Node: acc_delete95036
Node: acc_update_device97283
Node: acc_update_self98857
Node: acc_map_data100447
Node: acc_unmap_data101132
Node: acc_deviceptr101653
Node: acc_hostptr102223
Node: acc_is_present102787
Node: acc_memcpy_to_device104314
Node: acc_memcpy_from_device104977
Node: acc_attach105644
Node: acc_detach106291
Node: acc_get_current_cuda_device107070
Node: acc_get_current_cuda_context107655
Node: acc_get_cuda_stream108255
Node: acc_set_cuda_stream108846
Node: acc_prof_register109517
Node: acc_prof_unregister110076
Node: acc_prof_lookup110643
Node: acc_register_library111164
Node: OpenACC Environment Variables111730
Node: ACC_DEVICE_TYPE112302
Node: ACC_DEVICE_NUM112538
Node: ACC_PROFLIB112792
Node: GCC_ACC_NOTIFY113123
Node: CUDA Streams Usage113343
Ref: CUDA Streams Usage-Footnote-1115244
Node: OpenACC Library Interoperability115353
Ref: OpenACC Library Interoperability-Footnote-1121721
Ref: OpenACC Library Interoperability-Footnote-2121973
Node: OpenACC Profiling Interface122181
Node: The libgomp ABI132205
Node: Implementing MASTER construct133058
Node: Implementing CRITICAL construct133474
Node: Implementing ATOMIC construct134215
Node: Implementing FLUSH construct134698
Node: Implementing BARRIER construct134971
Node: Implementing THREADPRIVATE construct135242
Node: Implementing PRIVATE clause135897
Node: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses136480
Node: Implementing REDUCTION clause137806
Node: Implementing PARALLEL construct138365
Node: Implementing FOR construct139624
Node: Implementing ORDERED construct141624
Node: Implementing SECTIONS construct141932
Node: Implementing SINGLE construct142700
Node: Implementing OpenACC's PARALLEL construct143414
Node: Reporting Bugs143674
Node: Copying144037
Node: GNU Free Documentation License181583
Node: Funding206706
Node: Library Index209232

End Tag Table


Local Variables:
coding: utf-8
End: