I apologise in advance for the size of this check-in. At Intel we do

understand that this is not friendly, and are working to change our
internal code-development to make it easier to make development
features available more frequently and in finer (more functional)
chunks. Unfortunately we haven't got that in place yet, and unpicking
this into multiple separate check-ins would be non-trivial, so please
bear with me on this one. We should be better in the future.

Apologies over, what do we have here?

GGC 4.9 compatibility
--------------------
* We have implemented the new entrypoints used by code compiled by GCC
4.9 to implement the same functionality in gcc 4.8. Therefore code
compiled with gcc 4.9 that used to work will continue to do so.
However, there are some other new entrypoints (associated with task
cancellation) which are not implemented. Therefore user code compiled
by gcc 4.9 that uses these new features will not link against the LLVM
runtime. (It remains unclear how to handle those entrypoints, since
the GCC interface has potentially unpleasant performance implications
for join barriers even when cancellation is not used)

--- new parallel entry points ---
new entry points that aren't OpenMP 4.0 related
These are implemented fully :-
      GOMP_parallel_loop_dynamic()
      GOMP_parallel_loop_guided()
      GOMP_parallel_loop_runtime()
      GOMP_parallel_loop_static()
      GOMP_parallel_sections()
      GOMP_parallel()

--- cancellation entry points ---
Currently, these only give a runtime error if OMP_CANCELLATION is true
because our plain barriers don't check for cancellation while waiting
        GOMP_barrier_cancel()
        GOMP_cancel()
        GOMP_cancellation_point()
        GOMP_loop_end_cancel()
        GOMP_sections_end_cancel()

--- taskgroup entry points ---
These are implemented fully.
      GOMP_taskgroup_start()
      GOMP_taskgroup_end()

--- target entry points ---
These are empty (as they are in libgomp)
     GOMP_target()
     GOMP_target_data()
     GOMP_target_end_data()
     GOMP_target_update()
     GOMP_teams()

Improvements in Barriers and Fork/Join
--------------------------------------
* Barrier and fork/join code is now in its own file (which makes it
easier to understand and modify).
* Wait/release code is now templated and in its own file; suspend/resume code is also templated
* There's a new, hierarchical, barrier, which exploits the
cache-hierarchy of the Intel(r) Xeon Phi(tm) coprocessor to improve
fork/join and barrier performance.

***BEWARE*** the new source files have *not* been added to the legacy
Cmake build system. If you want to use that fixes wil be required.

Statistics Collection Code
--------------------------
* New code has been added to collect application statistics (if this
is enabled at library compile time; by default it is not). The
statistics code itself is generally useful, the lightweight timing
code uses the X86 rdtsc instruction, so will require changes for other
architectures.
The intent of this code is not for users to tune their codes but
rather 
1) For timing code-paths inside the runtime
2) For gathering general properties of OpenMP codes to focus attention
on which OpenMP features are most used. 

Nested Hot Teams
----------------
* The runtime now maintains more state to reduce the overhead of
creating and destroying inner parallel teams. This improves the
performance of code that repeatedly uses nested parallelism with the
same resource allocation. Set the new KMP_HOT_TEAMS_MAX_LEVEL
envirable to a depth to enable this (and, of course, OMP_NESTED=true
to enable nested parallelism at all).

Improved Intel(r) VTune(Tm) Amplifier support
---------------------------------------------
* The runtime provides additional information to Vtune via the
itt_notify interface to allow it to display better OpenMP specific
analyses of load-imbalance.

Support for OpenMP Composite Statements
---------------------------------------
* Implement new entrypoints required by some of the OpenMP 4.1
composite statements.

Improved ifdefs
---------------
* More separation of concepts ("Does this platform do X?") from
platforms ("Are we compiling for platform Y?"), which should simplify
future porting.


ScaleMP* contribution
---------------------
Stack padding to improve the performance in their environment where
cross-node coherency is managed at the page level.

Redesign of wait and release code
---------------------------------
The code is simplified and performance improved.

Bug Fixes
---------
    *Fixes for Windows multiple processor groups.
    *Fix Fortran module build on Linux: offload attribute added.
    *Fix entry names for distribute-parallel-loop construct to be consistent with the compiler codegen.
    *Fix an inconsistent error message for KMP_PLACE_THREADS environment variable.

llvm-svn: 219214

1 files changed, 23 insertions, 1 deletions

diff --git a/openmp/runtime/doc/doxygen/libomp_interface.h b/openmp/runtime/doc/doxygen/libomp_interface.h
index b4be75cd0a1..e0d39e64932 100644
--- a/openmp/runtime/doc/doxygen/libomp_interface.h
+++ b/openmp/runtime/doc/doxygen/libomp_interface.h
@@ -208,6 +208,7 @@ are documented in different modules.
  - @ref THREADPRIVATE functions to support thread private data, copyin etc

  - @ref SYNCHRONIZATION functions to support `omp critical`, `omp barrier`, `omp master`, reductions etc

  - @ref ATOMIC_OPS functions to support atomic operations

+ - @ref STATS_GATHERING macros to support developer profiling of libiomp5

  - Documentation on tasking has still to be written...

 

 @section SEC_EXAMPLES Examples

@@ -319,8 +320,29 @@ These functions are used for implementing barriers.
 @defgroup THREADPRIVATE Thread private data support

 These functions support copyin/out and thread private data.

 

+@defgroup STATS_GATHERING Statistics Gathering from OMPTB

+These macros support profiling the libiomp5 library.  Use --stats=on when building with build.pl to enable

+and then use the KMP_* macros to profile (through counts or clock ticks) libiomp5 during execution of an OpenMP program.

+

+@section sec_stats_env_vars Environment Variables

+

+This section describes the environment variables relevent to stats-gathering in libiomp5

+

+@code

+KMP_STATS_FILE

+@endcode

+This environment variable is set to an output filename that will be appended *NOT OVERWRITTEN* if it exists.  If this environment variable is undefined, the statistics will be output to stderr

+

+@code

+KMP_STATS_THREADS

+@endcode

+This environment variable indicates to print thread-specific statistics as well as aggregate statistics.  Each thread's statistics will be shown as well as the collective sum of all threads.  The values "true", "on", "1", "yes" will all indicate to print per thread statistics.

+

 @defgroup TASKING Tasking support

-These functions support are used to implement tasking constructs.

+These functions support tasking constructs.

+

+@defgroup USER User visible functions

+These functions can be called directly by the user, but are runtime library specific, rather than being OpenMP interfaces.

 

 */