openmp: Fix up handling of reduction clause on constructs combined with target [PR99928]

The reduction clause should be copied as map (tofrom: ) to combined target if
present, but as we need different handling of array sections between map and reduction,
doing that during gimplification would be harder.

So, this patch adds them during splitting, and similarly to firstprivate adds them
with a new flag that they should be just ignored/removed if an explicit map clause
of the same list item is present.

The exact rules are to be decided in https://github.com/OpenMP/spec/issues/2766
so this patch just implements something that is IMHO reasonable and exact detailed
testcases for the cornercases will follow once it is clarified.

2021-05-28  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/99928
gcc/
	* tree.h (OMP_CLAUSE_MAP_IMPLICIT): Define.
gcc/c-family/
	* c-omp.c (c_omp_split_clauses): For reduction clause if combined with
	target add a map tofrom clause with OMP_CLAUSE_MAP_IMPLICIT.
gcc/c/
	* c-typeck.c (handle_omp_array_sections): Copy OMP_CLAUSE_MAP_IMPLICIT.
	(c_finish_omp_clauses): Move not just OMP_CLAUSE_FIRSTPRIVATE_IMPLICIT
	marked clauses last, but also OMP_CLAUSE_MAP_IMPLICIT.  Add
	map_firstprivate_head bitmap, set it for GOMP_MAP_FIRSTPRIVATE_POINTER
	maps and silently remove OMP_CLAUSE_FIRSTPRIVATE_IMPLICIT if it is
	present too.  For OMP_CLAUSE_MAP_IMPLICIT silently remove the clause
	if present in map_head, map_field_head or map_firstprivate_head
	bitmaps.
gcc/cp/
	* semantics.c (handle_omp_array_sections): Copy
	OMP_CLAUSE_MAP_IMPLICIT.
	(finish_omp_clauses): Move not just OMP_CLAUSE_FIRSTPRIVATE_IMPLICIT
	marked clauses last, but also OMP_CLAUSE_MAP_IMPLICIT.  Add
	map_firstprivate_head bitmap, set it for GOMP_MAP_FIRSTPRIVATE_POINTER
	maps and silently remove OMP_CLAUSE_FIRSTPRIVATE_IMPLICIT if it is
	present too.  For OMP_CLAUSE_MAP_IMPLICIT silently remove the clause
	if present in map_head, map_field_head or map_firstprivate_head
	bitmaps.
gcc/testsuite/
	* c-c++-common/gomp/pr99928-8.c: Remove all xfails.
	* c-c++-common/gomp/pr99928-9.c: Likewise.
	* c-c++-common/gomp/pr99928-10.c: Likewise.
	* c-c++-common/gomp/pr99928-16.c: New test.

1 files changed, 5 insertions, 0 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index 37aca89..5935d0e 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1654,6 +1654,11 @@ class auto_suppress_location_wrappers
    variable.  */
 #define OMP_CLAUSE_MAP_IN_REDUCTION(NODE) \
   TREE_PRIVATE (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_MAP))
+/* Nonzero on map clauses added implicitly for reduction clauses on combined
+   or composite constructs.  They shall be removed if there is an explicit
+   map clause.  */
+#define OMP_CLAUSE_MAP_IMPLICIT(NODE) \
+  (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_MAP)->base.default_def_flag)
 
 /* True on an OMP_CLAUSE_USE_DEVICE_PTR with an OpenACC 'if_present'
    clause.  */