This is the front-end portion of the Unified Shared Memory implementation.
It removes the "sorry, unimplemented message" in C, C++, and Fortran, and sets
flag_offload_memory, but is otherwise inactive, for now.

It also checks that -foffload-memory isn't set to an incompatible mode.

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_omp_requires): Allow "requires
	  unified_share_memory" and "unified_address".

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_omp_requires): Allow "requires
	unified_share_memory" and "unified_address".

gcc/fortran/ChangeLog:

	* openmp.cc (gfc_match_omp_requires): Allow "requires
	unified_share_memory" and "unified_address".

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/usm-1.c: New test.
	* c-c++-common/gomp/usm-4.c: New test.
	* gfortran.dg/gomp/usm-1.f90: New test.
	* gfortran.dg/gomp/usm-4.f90: New test.
---
 gcc/c/c-parser.cc                        | 22 ++++++++++++++++++++--
 gcc/cp/parser.cc                         | 22 ++++++++++++++++++++--
 gcc/fortran/openmp.cc                    | 13 +++++++++++++
 gcc/testsuite/c-c++-common/gomp/usm-1.c  |  4 ++++
 gcc/testsuite/c-c++-common/gomp/usm-4.c  |  4 ++++
 gcc/testsuite/gfortran.dg/gomp/usm-1.f90 |  6 ++++++
 gcc/testsuite/gfortran.dg/gomp/usm-4.f90 |  6 ++++++
 7 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/gomp/usm-1.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/usm-4.c
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/usm-1.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/usm-4.f90