Version 19.12.0 (December 31, 2019)

• Build
  • Both builds (Make and CMake) now generate legion_defines.h and
    realm_defines.h. By default these headers are generated in
    the source directory (Make) or build directory (CMake). This
    means that languages such as Regent and Python no longer
    require MAX_DIM to be specified explicitly
• Regent
  • Support for CUDA 10
  • Support for field polymorphic tasks
  • Substantially improved the generality of the index launch
    optimization. Task arguments of the form p[i+k] may now be
    used, where k is a variable defined outside of the loop
  • Add flag -foverride-demand-index-launch which can be used to
    force loops to be index launched in cases where the compiler
    cannot prove the disjointness of read-write region
    arguments
  • Added reductions for complex64
  • The scripts install.py and setup_env.py now use CMake to
    build Terra by default, which should improve portability on
    most machines
  • The behavior of -fcuda 1 has changed: this flag will now issue
    an error if CUDA cannot be enabled (e.g. because the build
    does not support CUDA, or because the machine has no
    GPUs). Omitting this flag will now enable CUDA if it is
    available (and will not error if it is not available).
    The behavior of -fopenmp 1 has changed similarly.
  • The behavior of __demand(__cuda) has changed. This will now
    issue an error if a loop is not eligible for the CUDA
    transformation, regardless of whether CUDA is actually
    available on the current machine or not. The behavior of
    __demand(__openmp) has changed similarly.
  • The annotation __allow(__cuda) is now permitted, and permits
    (but does not require) tasks to be optimized with CUDA.
  • Experimental support for 2D kernel launch in the CUDA code generation
• Python
  • Add support for copies
  • Copies and fills now support multiple fields
  • Tasks (including index launches) now support setting the mapper
    ID and tag
• Legion
  • A major overhaul of the Legion physical analysis to use an
    approach based on bounding volume hierarchies. The change is
    not visible to users, but will likely impact performance. Most
    programs will get faster; programs that create many partitions
    frequently on the fly may get slower. The later case will be fixed
    in an upcoming release.
  • Added support for indirect copy operations such as gather and
    scatter onto existing copy launchers
• Realm
  • Event::subscribe allows polling via Event::has_triggered to
    (eventually) succeed
  • Addition of CompletionQueue objects that allow multiple unordered
    Event triggers to be efficiently handled by a single consumer
  • Support for omp_get_level, omp_in_parallel, and
    omp_set_num_threads in tasks running on OpenMP processors
  • Support for unstructured scatter and/or gather in copies. (Handling
    structured cases as well as fills/reductions remains a work in
    progress.)
  • Removed all calls to Event::wait from inside other Realm API calls.
    Applications now must make sure that index spaces and instance
    metadata are valid before use. For details, see: #465