OpenMP 5.0: requires directive

OpenMP 5.0: requires directive

This is a merge of:
https://gcc.gnu.org/pipermail/gcc-patches/2021-January/563393.html

This patch completes more of the reverse_offload, unified_address, and
unified_shared_memory clauses for the OpenMP 5.0 requires directive,
including runtime verification of the offload target.
(currently no offload devices actually support above features, only
warning messages are emitted)

This may possibly reverted/updated when a final patch is approved
for mainline.

2021-02-02  Chung-Lin Tang  <cltang@codesourcery.com>

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_declaration_or_fndef): Set
	OMP_REQUIRES_TARGET_USED in omp_requires_mask if function has
	"omp declare target" attribute.
	(c_parser_omp_target_data): Set OMP_REQUIRES_TARGET_USED in
	omp_requires_mask.
	(c_parser_omp_target_enter_data): Likewise.
	(c_parser_omp_target_exit_data): Likewise.
	(c_parser_omp_requires): Adjust to only mention "not implemented yet"
	for OMP_REQUIRES_DYNAMIC_ALLOCATORS.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_simple_declaration): Set
	OMP_REQUIRES_TARGET_USED in omp_requires_mask if function has
	"omp declare target" attribute.
	(cp_parser_omp_target_data): Set OMP_REQUIRES_TARGET_USED in
	omp_requires_mask.
	(cp_parser_omp_target_enter_data): Likewise.
	(cp_parser_omp_target_exit_data): Likewise.
	(cp_parser_omp_requires): Adjust to only mention "not implemented yet"
	for OMP_REQUIRES_DYNAMIC_ALLOCATORS.

gcc/fortran/ChangeLog:

	* openmp.cc (gfc_check_omp_requires): Fix REVERSE_OFFLOAD typo.
	(gfc_match_omp_requires): Adjust to only mention "not implemented yet"
	for OMP_REQUIRES_DYNAMIC_ALLOCATORS.
	* parse.cc ("tree.h"): Add include.
	("omp-general.h"): Likewise.
	(gfc_parse_file): Add code to merge omp_requires to omp_requires_mask.

gcc/ChangeLog:

	* omp-offload.cc (omp_finish_file): Add code to create OpenMP requires
	mask variable in .gnu.gomp_requires section if needed.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/requires-4.c: Remove prune of "not supported yet".
	* gfortran.dg/gomp/requires-4.f90: Fix REVERSE_OFFLOAD typo.
	* gfortran.dg/gomp/requires-8.f90: Likewise.

include/ChangeLog:

	* gomp-constants.h (GOMP_REQUIRES_UNIFIED_ADDRESS): New symbol.
	(GOMP_REQUIRES_UNIFIED_SHARED_MEMORY): Likewise.
	(GOMP_REQUIRES_REVERSE_OFFLOAD): Likewise.

libgcc/ChangeLog:

	* offloadstuff.c (__requires_mask_table): New symbol to mark start of
	.gnu.gomp_requires section.
	(__requires_mask_table_end): New symbol to mark end of
	.gnu.gomp_requires section.

libgomp/ChangeLog:

	* libgomp-plugin.h (GOMP_OFFLOAD_supported_features): New declaration.
	* libgomp.h (struct gomp_device_descr): New 'supported_features_func'
	plugin hook field.
	* oacc-host.c (host_supported_features): New host hook function.
	(host_dispatch): Initialize 'supported_features_func' host hook.
	* plugin/plugin-gcn.c (GOMP_OFFLOAD_supported_features): New function.
	* plugin/plugin-nvptx.c (GOMP_OFFLOAD_supported_features): Likewise.
	* target.c (<stdio.h>): Add include of standard header.
	(gomp_requires_mask): New static variable.
	(__requires_mask_table): New declaration.
	(__requires_mask_table_end): Likewise.
	(gomp_load_plugin_for_device): Add loading of 'supported_features' hook.
	(gomp_target_init): Add code to summarize .gnu._gomp_requires section
	mask values, emit error if inconsistency found.

	* testsuite/libgomp.c-c++-common/requires-1.c: New test.
	* testsuite/libgomp.c-c++-common/requires-1-aux.c: New file linked with
	above test.
	* testsuite/libgomp.c-c++-common/requires-2.c: New test.
	* testsuite/libgomp.c-c++-common/requires-2-aux.c: New file linked with
	above test.

liboffloadmic/ChangeLog:

	* plugin/libgomp-plugin-intelmic.cpp (GOMP_OFFLOAD_supported_features):
	New function.