Add a restriction on allocate clause (OpenMP 5.0)

An allocate clause in target region must specify an allocator
unless the compilation unit has requires construct with
dynamic_allocators clause.  Current implementation of the allocate
clause did not check for this restriction. This patch fills that
gap.

gcc/ChangeLog:

	* omp-low.cc (omp_maybe_offloaded_ctx): New prototype.
	(scan_sharing_clauses):  Check a restriction on allocate clause.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/allocate-2.c: Add tests.
	* c-c++-common/gomp/allocate-8.c: New test.
	* gfortran.dg/gomp/allocate-3.f90: Add tests.
	* gcc.dg/gomp/pr104517.c: Update.

gcc/omp-low.cc

@@ -195,6 +195,7 @@ static vec<gomp_task *> task_cpyfns;
 
 static void scan_omp (gimple_seq *, omp_context *);
 static tree scan_omp_1_op (tree *, int *, void *);
+static bool omp_maybe_offloaded_ctx (omp_context *ctx);
 
 #define WALK_SUBSTMTS  \
     case GIMPLE_BIND: \
@@ -1154,6 +1155,15 @@ scan_sharing_clauses (tree clauses, omp_context *ctx)
 	    || !integer_onep (OMP_CLAUSE_ALLOCATE_ALLOCATOR (c))
 	    || OMP_CLAUSE_ALLOCATE_ALIGN (c) != NULL_TREE))
       {
+	/* The allocate clauses that appear on a target construct or on
+	   constructs in a target region must specify an allocator expression
+	   unless a requires directive with the dynamic_allocators clause
+	   is present in the same compilation unit.  */
+	if (OMP_CLAUSE_ALLOCATE_ALLOCATOR (c) == NULL_TREE
+	    && ((omp_requires_mask & OMP_REQUIRES_DYNAMIC_ALLOCATORS) == 0)
+	    && omp_maybe_offloaded_ctx (ctx))
+	  error_at (OMP_CLAUSE_LOCATION (c), "%<allocate%> clause must"
+		    " specify an allocator here");
 	if (ctx->allocate_map == NULL)
 	  ctx->allocate_map = new hash_map<tree, tree>;
 	tree val = integer_zero_node;

gcc/testsuite/c-c++-common/gomp/allocate-2.c

@@ -43,3 +43,18 @@ foo (int x, int z)
   #pragma omp parallel private (x) allocate (0 : x)	/* { dg-error "'allocate' clause allocator expression has type 'int' rather than 'omp_allocator_handle_t'" } */
   bar (x, &x, 0);
 }
+
+void
+foo1 ()
+{
+  int a = 10;
+#pragma omp target
+  {
+    #pragma omp parallel private (a) allocate(a) // { dg-error "'allocate' clause must specify an allocator here" }
+    a = 20;
+  }
+#pragma omp target private(a) allocate(a) // { dg-error "'allocate' clause must specify an allocator here" }
+  {
+    a = 30;
+  }
+}

gcc/testsuite/c-c++-common/gomp/allocate-8.c

@@ -0,0 +1,18 @@
+#pragma omp requires dynamic_allocators
+void
+foo ()
+{
+  int a = 10;
+#pragma omp parallel private (a) allocate(a)
+  a = 20;
+#pragma omp target
+  {
+    #pragma omp parallel private (a) allocate(a)
+    a = 30;
+  }
+#pragma omp target private(a) allocate(a)
+  {
+    a = 40;
+  }
+}
+

gcc/testsuite/gcc.dg/gomp/pr104517.c

@@ -2,11 +2,13 @@
 /* { dg-do compile } */
 /* { dg-options "-O1 -fcompare-debug -fopenmp -fno-tree-ter -save-temps" } */
 
-enum {
-  omp_default_mem_alloc,
-  omp_large_cap_mem_alloc,
-  omp_const_mem_alloc,
-  omp_high_bw_mem_alloc
+typedef enum omp_allocator_handle_t
+{
+  omp_null_allocator = 0,
+  omp_default_mem_alloc = 1,
+  omp_large_cap_mem_alloc = 2,
+  omp_const_mem_alloc = 3,
+  omp_high_bw_mem_alloc = 4,
 } omp_allocator_handle_t;
 
 int t, bar_nte, bar_tl, bar_i3, bar_dd;
@@ -23,7 +25,7 @@ bar (int *idp, int s, int nth, int g, int nta, int fi, int pp, int *q,
   int p = 0, i2 = 0, i1 = 0, m = 0, d = 0;
 
 #pragma omp target parallel for                               \
-  device(p) firstprivate (f) allocate (f) in_reduction(+:r2)
+  device(p) firstprivate (f) allocate (omp_default_mem_alloc:f) in_reduction(+:r2)
   for (int i = 0; i < 4; i++)
     ll++;
 
@@ -31,8 +33,8 @@ bar (int *idp, int s, int nth, int g, int nta, int fi, int pp, int *q,
   device(d) map (m)                                                     \
   if (target: p) firstprivate (f) defaultmap(tofrom: scalar) is_device_ptr (idp) \
   if (parallel: i2) reduction(+:r) num_threads (nth) linear (ll)        \
-  schedule(static) collapse(1) nowait depend(inout: d) allocate (f)     \
-  in_reduction(+:r2)
+  schedule(static) collapse(1) nowait depend(inout: d) \
+  allocate (omp_default_mem_alloc:f) in_reduction(+:r2)
   for (int i = 0; i < 4; i++)
     ll++;
 

gcc/testsuite/gfortran.dg/gomp/allocate-3.f90

@@ -12,3 +12,17 @@ subroutine foo(x)
   !$omp end parallel do simd
 
 end subroutine
+
+subroutine bar(a)
+  implicit none
+  integer  :: a
+!$omp target
+  !$omp parallel private (a) allocate(a) ! { dg-error "'allocate' clause must specify an allocator here" }
+    a = 20
+  !$omp end parallel
+!$omp end target
+
+!$omp target private(a) allocate(a) ! { dg-error "'allocate' clause must specify an allocator here" }
+  a = 30;
+!$omp end target
+end subroutine