OpenMP 5.0: Remove array section base-pointer mapping semantics and other front-end adjustments

This patch implements three pieces of functionality:

(1) Adjust array section mapping to have standards conforming behavior,
mapping array sections should *NOT* also map the base-pointer:

struct S { int *ptr; ... };
struct S s;

Instead of generating this during gimplify:
                              map(to:*_1 [len: 400]) map(attach:s.ptr [bias: 0])

Now, adjust to:

(i.e. do not map the base-pointer together. The attach operation is still
generated, and if s.ptr is already mapped prior, attachment will happen)

The correct way of achieving the base-pointer-also-mapped behavior would be to
use:

(A small Fortran front-end patch to trans-openmp.c:gfc_trans_omp_array_section
 is also included, which removes generation of a GOMP_MAP_ALWAYS_POINTER for
 array types, which appears incorrect and causes a regression in
 libgomp.fortranlibgomp.fortran/struct-elem-map-1.f90)

(2) Related to the first item above, are fixes in libgomp/target.c to not
overwrite attached pointers when handling device<->host copies, mainly for the
"always" case.

(3) The third is a set of changes to the C/C++ front-ends to extend the allowed
component access syntax in map clauses. These changes are enabled for both
OpenACC and OpenMP.

gcc/c/ChangeLog:

	* c-parser.c (struct omp_dim): New struct type for use inside
	c_parser_omp_variable_list.
	(c_parser_omp_variable_list): Allow multiple levels of array and
	component accesses in array section base-pointer expression.
	(c_parser_omp_clause_to): Set 'allow_deref' to true in call to
	c_parser_omp_var_list_parens.
	(c_parser_omp_clause_from): Likewise.
	* c-typeck.c (handle_omp_array_sections_1): Extend allowed range
	of base-pointer expressions involving INDIRECT/MEM/ARRAY_REF and
	POINTER_PLUS_EXPR.
	(c_finish_omp_clauses): Extend allowed ranged of expressions
	involving INDIRECT/MEM/ARRAY_REF and POINTER_PLUS_EXPR.

gcc/cp/ChangeLog:

	* parser.c (struct omp_dim): New struct type for use inside
	cp_parser_omp_var_list_no_open.
	(cp_parser_omp_var_list_no_open): Allow multiple levels of array and
	component accesses in array section base-pointer expression.
	(cp_parser_omp_all_clauses): Set 'allow_deref' to true in call to
	cp_parser_omp_var_list for to/from clauses.
	* semantics.c (handle_omp_array_sections_1): Extend allowed range
	of base-pointer expressions involving INDIRECT/MEM/ARRAY_REF and
	POINTER_PLUS_EXPR.
	(handle_omp_array_sections): Adjust pointer map generation of
	references.
	(finish_omp_clauses): Extend allowed ranged of expressions
	involving INDIRECT/MEM/ARRAY_REF and POINTER_PLUS_EXPR.

gcc/fortran/ChangeLog:

	* trans-openmp.c (gfc_trans_omp_array_section): Do not generate
	GOMP_MAP_ALWAYS_POINTER map for main array maps of ARRAY_TYPE type.

gcc/ChangeLog:

	* gimplify.c (extract_base_bit_offset): Add 'tree *offsetp' parameter,
	accomodate case where 'offset' return of get_inner_reference is
	non-NULL.
	(is_or_contains_p): Further robustify conditions.
	(omp_target_reorder_clauses): In alloc/to/from sorting phase, also
	move following GOMP_MAP_ALWAYS_POINTER maps along.  Add new sorting
	phase where we make sure pointers with an attach/detach map are ordered
	correctly.
	(gimplify_scan_omp_clauses): Add modifications to avoid creating
	GOMP_MAP_STRUCT and associated alloc map for attach/detach maps.

gcc/testsuite/ChangeLog:

	* c-c++-common/goacc/deep-copy-arrayofstruct.c: Adjust testcase.
	* c-c++-common/gomp/target-enter-data-1.c: New testcase.
	* c-c++-common/gomp/target-implicit-map-2.c: New testcase.

libgomp/ChangeLog:

	* target.c (gomp_map_vars_existing): Make sure attached pointer is
	not overwritten during cross-host/device copying.
	(gomp_update): Likewise.
	(gomp_exit_data): Likewise.
	* testsuite/libgomp.c++/target-11.C: Adjust testcase.
	* testsuite/libgomp.c++/target-12.C: Likewise.
	* testsuite/libgomp.c++/target-15.C: Likewise.
	* testsuite/libgomp.c++/target-16.C: Likewise.
	* testsuite/libgomp.c++/target-17.C: Likewise.
	* testsuite/libgomp.c++/target-21.C: Likewise.
	* testsuite/libgomp.c++/target-23.C: Likewise.
	* testsuite/libgomp.c/target-23.c: Likewise.
	* testsuite/libgomp.c/target-29.c: Likewise.
	* testsuite/libgomp.c-c++-common/target-implicit-map-2.c: New testcase.

2 files changed, 11 insertions, 11 deletions

diff --git a/libgomp/testsuite/libgomp.c/target-23.c b/libgomp/testsuite/libgomp.c/target-23.c
index fb1532a07b2..d56b13acf82 100644
--- a/libgomp/testsuite/libgomp.c/target-23.c
+++ b/libgomp/testsuite/libgomp.c/target-23.c
@@ -8,7 +8,7 @@ main ()
   int u[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }, err = 0;
   struct S s = { 9, u + 3, { 10, 11, 12, 13, 14 } };
   int *v = u + 4;
-  #pragma omp target enter data map (to: s.s, s.u[0:5]) map (alloc: s.v[1:3])
+  #pragma omp target enter data map (to: s.s, s.u, s.u[0:5]) map (alloc: s.v[1:3])
   s.s++;
   u[3]++;
   s.v[1]++;
diff --git a/libgomp/testsuite/libgomp.c/target-29.c b/libgomp/testsuite/libgomp.c/target-29.c
index e5095a1b6b8..4a286649811 100644
--- a/libgomp/testsuite/libgomp.c/target-29.c
+++ b/libgomp/testsuite/libgomp.c/target-29.c
@@ -14,7 +14,7 @@ foo (struct S s)
     d = id;
 
   int err;
-  #pragma omp target map(tofrom: s.a, s.b, s.c[1:2], s.d[-2:3]) map(to: sep) map(from: err)
+  #pragma omp target map(tofrom: s.a, s.b, s.c[1:2], s.d, s.d[-2:3]) map(to: sep) map(from: err)
   {
     err = s.a != 11 || s.b[0] != 12 || s.b[1] != 13;
     err |= s.c[1] != 15 || s.c[2] != 16 || s.d[-2] != 18 || s.d[-1] != 19 || s.d[0] != 20;
@@ -35,7 +35,7 @@ foo (struct S s)
 	  || omp_target_is_present (s.d, d)
 	  || omp_target_is_present (&s.d[-2], d)))
     abort ();
-  #pragma omp target data map(alloc: s.a, s.b, s.c[1:2], s.d[-2:3])
+  #pragma omp target data map(alloc: s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
   {
     if (!omp_target_is_present (&s.a, d)
 	|| !omp_target_is_present (s.b, d)
@@ -43,15 +43,15 @@ foo (struct S s)
 	|| !omp_target_is_present (s.d, d)
 	|| !omp_target_is_present (&s.d[-2], d))
       abort ();
-    #pragma omp target update to(s.a, s.b, s.c[1:2], s.d[-2:3])
-    #pragma omp target map(alloc: s.a, s.b, s.c[1:2], s.d[-2:3]) map(from: err)
+    #pragma omp target update to(s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
+    #pragma omp target map(alloc: s.a, s.b, s.c[1:2], s.d, s.d[-2:3]) map(from: err)
     {
       err = s.a != 50 || s.b[0] != 49 || s.b[1] != 48;
       err |= s.c[1] != 47 || s.c[2] != 46 || s.d[-2] != 45 || s.d[-1] != 44 || s.d[0] != 43;
       s.a = 17; s.b[0] = 18; s.b[1] = 19;
       s.c[1] = 20; s.c[2] = 21; s.d[-2] = 22; s.d[-1] = 23; s.d[0] = 24;
     }
-    #pragma omp target update from(s.a, s.b, s.c[1:2], s.d[-2:3])
+    #pragma omp target update from(s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
   }
   if (sep
       && (omp_target_is_present (&s.a, d)
@@ -66,29 +66,29 @@ foo (struct S s)
   if (err) abort ();
   s.a = 33; s.b[0] = 34; s.b[1] = 35;
   s.c[1] = 36; s.c[2] = 37; s.d[-2] = 38; s.d[-1] = 39; s.d[0] = 40;
-  #pragma omp target enter data map(alloc: s.a, s.b, s.c[1:2], s.d[-2:3])
+  #pragma omp target enter data map(alloc: s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
   if (!omp_target_is_present (&s.a, d)
       || !omp_target_is_present (s.b, d)
       || !omp_target_is_present (&s.c[1], d)
       || !omp_target_is_present (s.d, d)
       || !omp_target_is_present (&s.d[-2], d))
     abort ();
-  #pragma omp target enter data map(always, to: s.a, s.b, s.c[1:2], s.d[-2:3])
-  #pragma omp target map(alloc: s.a, s.b, s.c[1:2], s.d[-2:3]) map(from: err)
+  #pragma omp target enter data map(always, to: s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
+  #pragma omp target map(alloc: s.a, s.b, s.c[1:2], s.d, s.d[-2:3]) map(from: err)
   {
     err = s.a != 33 || s.b[0] != 34 || s.b[1] != 35;
     err |= s.c[1] != 36 || s.c[2] != 37 || s.d[-2] != 38 || s.d[-1] != 39 || s.d[0] != 40;
     s.a = 49; s.b[0] = 48; s.b[1] = 47;
     s.c[1] = 46; s.c[2] = 45; s.d[-2] = 44; s.d[-1] = 43; s.d[0] = 42;
   }
-  #pragma omp target exit data map(always, from: s.a, s.b, s.c[1:2], s.d[-2:3])
+  #pragma omp target exit data map(always, from: s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
   if (!omp_target_is_present (&s.a, d)
       || !omp_target_is_present (s.b, d)
       || !omp_target_is_present (&s.c[1], d)
       || !omp_target_is_present (s.d, d)
       || !omp_target_is_present (&s.d[-2], d))
     abort ();
-  #pragma omp target exit data map(release: s.a, s.b, s.c[1:2], s.d[-2:3])
+  #pragma omp target exit data map(release: s.a, s.b, s.c[1:2], s.d, s.d[-2:3])
   if (sep
       && (omp_target_is_present (&s.a, d)
 	  || omp_target_is_present (s.b, d)