openmp: Relax handling of implicit map vs. existing device mappings

This patch implements relaxing the requirements when a map with the implicit
attribute encounters an overlapping existing map. As the OpenMP 5.0 spec
describes on page 320, lines 18-27 (and 5.1 spec, page 352, lines 13-22):

"If a single contiguous part of the original storage of a list item with an
 implicit data-mapping attribute has corresponding storage in the device data
 environment prior to a task encountering the construct that is associated with
 the map clause, only that part of the original storage will have corresponding
 storage in the device data environment as a result of the map clause."

2021-11-12  Chung-Lin Tang  <cltang@codesourcery.com>

include/ChangeLog:

	* gomp-constants.h (GOMP_MAP_FLAG_SPECIAL_3): Define special bit macro.
	(GOMP_MAP_IMPLICIT): New special map kind bits value.
	(GOMP_MAP_FLAG_SPECIAL_BITS): Define helper mask for whole set of
	special map kind bits.
	(GOMP_MAP_IMPLICIT_P): New predicate macro for implicit map kinds.

gcc/ChangeLog:

	* tree.h (OMP_CLAUSE_MAP_RUNTIME_IMPLICIT_P): New access macro for
	'implicit' bit, using 'base.deprecated_flag' field of tree_node.
	* tree-pretty-print.c (dump_omp_clause): Add support for printing
	implicit attribute in tree dumping.
	* gimplify.c (gimplify_adjust_omp_clauses_1):
	Set OMP_CLAUSE_MAP_RUNTIME_IMPLICIT_P to 1 if map clause is implicitly
	created.
	(gimplify_adjust_omp_clauses): Adjust place of adding implicitly created
	clauses, from simple append, to starting of list, after non-map clauses.
	* omp-low.c (lower_omp_target): Add GOMP_MAP_IMPLICIT bits into kind
	values passed to libgomp for implicit maps.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/target-implicit-map-1.c: New test.
	* c-c++-common/goacc/combined-reduction.c: Adjust scan test pattern.
	* c-c++-common/goacc/firstprivate-mappings-1.c: Likewise.
	* c-c++-common/goacc/mdc-1.c: Likewise.
	* g++.dg/goacc/firstprivate-mappings-1.C: Likewise.

libgomp/ChangeLog:

	* target.c (gomp_map_vars_existing): Add 'bool implicit' parameter, add
	implicit map handling to allow a "superset" existing map as valid case.
	(get_kind): Adjust to filter out GOMP_MAP_IMPLICIT bits in return value.
	(get_implicit): New function to extract implicit status.
	(gomp_map_fields_existing): Adjust arguments in calls to
	gomp_map_vars_existing, and add uses of get_implicit.
	(gomp_map_vars_internal): Likewise.
	* testsuite/libgomp.c-c++-common/target-implicit-map-1.c: New test.

1 files changed, 14 insertions, 0 deletions

diff --git a/include/gomp-constants.h b/include/gomp-constants.h
index ebd0801..3e42d71 100644
--- a/include/gomp-constants.h
+++ b/include/gomp-constants.h
@@ -40,11 +40,22 @@
 #define GOMP_MAP_FLAG_SPECIAL_0		(1 << 2)
 #define GOMP_MAP_FLAG_SPECIAL_1		(1 << 3)
 #define GOMP_MAP_FLAG_SPECIAL_2		(1 << 4)
+#define GOMP_MAP_FLAG_SPECIAL_3		(1 << 5)
 #define GOMP_MAP_FLAG_SPECIAL_4		(1 << 6)
 #define GOMP_MAP_FLAG_SPECIAL		(GOMP_MAP_FLAG_SPECIAL_1 \
 					 | GOMP_MAP_FLAG_SPECIAL_0)
 #define GOMP_MAP_DEEP_COPY		(GOMP_MAP_FLAG_SPECIAL_4 \
 					 | GOMP_MAP_FLAG_SPECIAL_2)
+/* This value indicates the map was created implicitly according to
+   OpenMP rules.  */
+#define GOMP_MAP_IMPLICIT		(GOMP_MAP_FLAG_SPECIAL_3 \
+					 | GOMP_MAP_FLAG_SPECIAL_4)
+/* Mask for entire set of special map kind bits.  */
+#define GOMP_MAP_FLAG_SPECIAL_BITS	(GOMP_MAP_FLAG_SPECIAL_0 \
+					 | GOMP_MAP_FLAG_SPECIAL_1 \
+					 | GOMP_MAP_FLAG_SPECIAL_2 \
+					 | GOMP_MAP_FLAG_SPECIAL_3 \
+					 | GOMP_MAP_FLAG_SPECIAL_4)
 /* Flag to force a specific behavior (or else, trigger a run-time error).  */
 #define GOMP_MAP_FLAG_FORCE		(1 << 7)
 
@@ -186,6 +197,9 @@ enum gomp_map_kind
 #define GOMP_MAP_ALWAYS_P(X) \
   (GOMP_MAP_ALWAYS_TO_P (X) || ((X) == GOMP_MAP_ALWAYS_FROM))
 
+#define GOMP_MAP_IMPLICIT_P(X) \
+  (((X) & GOMP_MAP_FLAG_SPECIAL_BITS) == GOMP_MAP_IMPLICIT)
+
 
 /* Asynchronous behavior.  Keep in sync with
    libgomp/{openacc.h,openacc.f90,openacc_lib.h}:acc_async_t.  */