OpenMP: 'allocate' directive - fixes for 'alignof' and [[omp::decl]]

Fixed a check to permit [[omp::decl(allocate,...)]] parsing in C.

Additionaly, we discussed that 'allocate align' should not affect
'alignof' to avoid issues like with:

  int a;
  _Alignas(_Alignof(a)) int b;
  #pragma omp allocate(a) align(128)
  _Alignas(_Alignof(a)) int c;

Thus, the alignment is no longer set in the C and Fortran front ends,
but for static variables now in varpool_node::finalize_decl.
(For stack variables, the alignment is handled in gimplify_bind_expr.)

NOTE: 'omp allocate' is not yet supported in C++.

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_omp_allocate): Only check scope if
	not in_omp_decl_attribute. Remove setting the alignment.

gcc/ChangeLog:

	* cgraphunit.cc (varpool_node::finalize_decl): Set alignment
	based on OpenMP's 'omp allocate' attribute/directive.

gcc/fortran/ChangeLog:

	* trans-decl.cc (gfc_finish_var_decl): Remove setting the alignment.

libgomp/ChangeLog:

	* libgomp.texi (Memory allocation): Mention (non-)effect of 'align'
	on _Alignof.
	* testsuite/libgomp.c/allocate-7.c: New test.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/allocate-18.c: Check that alignof is unaffected
	by 'omp allocate'.
	* c-c++-common/gomp/allocate-19.c: Likewise.

gcc/c/c-parser.cc

@@ -22158,7 +22158,7 @@ c_parser_omp_allocate (c_parser *parser)
 		    "%<allocate%> directive", var);
 	  continue;
 	}
-      if (!c_check_in_current_scope (var))
+      if (!parser->in_omp_decl_attribute && !c_check_in_current_scope (var))
 	{
 	  error_at (OMP_CLAUSE_LOCATION (nl),
 		    "%<allocate%> directive must be in the same scope as %qD",
@@ -22199,9 +22199,6 @@ c_parser_omp_allocate (c_parser *parser)
 	    = {EXPR_LOC_OR_LOC (allocator, OMP_CLAUSE_LOCATION (nl)), var};
 	  walk_tree (&allocator, c_check_omp_allocate_allocator_r, &data, NULL);
 	}
-      if (alignment)
-	SET_DECL_ALIGN (var, BITS_PER_UNIT * MAX (tree_to_uhwi (alignment),
-						  DECL_ALIGN_UNIT (var)));
       DECL_ATTRIBUTES (var) = tree_cons (get_identifier ("omp allocate"),
 					 build_tree_list (allocator, alignment),
 					 DECL_ATTRIBUTES (var));

gcc/cgraphunit.cc

@@ -983,6 +983,18 @@ varpool_node::finalize_decl (tree decl)
 	  && !DECL_ARTIFICIAL (node->decl)))
     node->force_output = true;
 
+  if (flag_openmp)
+    {
+      tree attr = lookup_attribute ("omp allocate", DECL_ATTRIBUTES (decl));
+      if (attr)
+	{
+	  tree align = TREE_VALUE (TREE_VALUE (attr));
+	  if (align)
+	    SET_DECL_ALIGN (decl, MAX (tree_to_uhwi (align) * BITS_PER_UNIT,
+				       DECL_ALIGN (decl)));
+	}
+    }
+
   if (symtab->state == CONSTRUCTION
       && (node->needed_p () || node->referred_to_p ()))
     enqueue_node (node);

gcc/fortran/trans-decl.cc

@@ -830,9 +830,6 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
       tree alloc = gfc_conv_constant_to_tree (n->u2.allocator);
       tree align = (n->u.align ? gfc_conv_constant_to_tree (n->u.align)
 			       : NULL_TREE);
-      if (align != NULL_TREE)
-	SET_DECL_ALIGN (decl, MAX (tree_to_uhwi (align),
-			DECL_ALIGN_UNIT (decl)) * BITS_PER_UNIT);
       DECL_ATTRIBUTES (decl)
 	= tree_cons (get_identifier ("omp allocate"),
 		     build_tree_list (alloc, align), DECL_ATTRIBUTES (decl));

gcc/testsuite/c-c++-common/gomp/allocate-18.c

@@ -17,14 +17,14 @@ typedef enum omp_allocator_handle_t
 
 void test0 ()
 {
-  int A1[5];
+  int A1[5], B1[5];
   #pragma omp allocate(A1) align(128) allocator(omp_default_mem_alloc)
   /* { dg-message "sorry, unimplemented: '#pragma omp allocate' not yet supported" "" { target c++ } .-1 } */
 
   #ifndef __cplusplus
-    _Static_assert (_Alignof(A1) == 128, "wrong alignment");
+    _Static_assert (_Alignof(A1) == _Alignof(B1), "wrong alignment");
   #elif __cplusplus >= 201103L
-     static_assert (alignof(A1) == 128, "wrong alignment");  /* { dg-bogus "static assertion failed: wrong alignment" "" { xfail { c++ && { ! c++98_only } } } } */
+     static_assert (alignof(A1) == alignof(B1), "wrong alignment"); 
   #endif
 }
 

gcc/testsuite/c-c++-common/gomp/allocate-19.c

@@ -19,14 +19,14 @@ typedef enum omp_allocator_handle_t
   __omp_allocator_handle_t_max__ = __UINTPTR_MAX__
 } omp_allocator_handle_t;
 
-static int A1[5] = {1,2,3,4,5};
+static int A1[5] = {1,2,3,4,5}, B1[5];
 #pragma omp allocate(A1) align(128) allocator(omp_default_mem_alloc)
 /* { dg-message "sorry, unimplemented: '#pragma omp allocate' not yet supported" "" { target c++ } .-1 } */
 
 #ifndef __cplusplus
-_Static_assert (_Alignof(A1) == 128, "wrong alignment");
+_Static_assert (_Alignof(A1) == _Alignof(B1), "wrong alignment");
 #elif __cplusplus >= 201103L
-static_assert (alignof(A1) == 128, "wrong alignment");  /* { dg-bogus "static assertion failed: wrong alignment" "" { xfail { c++ && { ! c++98_only } } } } */
+static_assert (alignof(A1) == alignof(B1), "wrong alignment");
 #endif
 
 
@@ -49,9 +49,9 @@ get ()
   /* { dg-message "sorry, unimplemented: '#pragma omp allocate' not yet supported" "" { target c++ } .-1 } */
 
 #ifndef __cplusplus
-  _Static_assert (_Alignof(q) == 1024, "wrong alignment");
+  _Static_assert (_Alignof(q) == _Alignof(int), "wrong alignment");
 #elif __cplusplus >= 201103L
-  static_assert (alignof(q) == 1024, "wrong alignment");  /* { dg-bogus "static assertion failed: wrong alignment" "" { xfail { c++ && { ! c++98_only } } } } */
+  static_assert (alignof(q) == alignof(int), "wrong alignment");
 #endif
 
   q += 1;

libgomp/libgomp.texi

@@ -6731,6 +6731,12 @@ The description below applies to:
       compiled with @option{-fopenmp-allocators}.  Additionally, all files that
       might explicitly or implicitly deallocate memory allocated that way must
       also be compiled with that option.
+@item The used alignment is the maximum of the value the @code{align} clause
+      and the alignment of the type after honoring, if present, the
+      @code{aligned} (@code{GNU::aligned}) attribute and C's @code{_Alignas}
+      and C++'s @code{alignas}.  However, the @code{align} clause of the
+      @code{allocate} directive has no effect on the value of C's
+      @code{_Alignof} and C++'s @code{alignof}.
 @end itemize
 
 For the available predefined allocators and, as applicable, their associated

libgomp/testsuite/libgomp.c/allocate-7.c

@@ -0,0 +1,54 @@
+/* TODO: move to ../libgomp.c-c++-common once C++ is implemented. */
+/* NOTE: { target c } is unsupported with with the C compiler.  */
+
+/* { dg-do run } */
+
+#include <omp.h>
+
+int AAA [[omp::decl(allocate,allocator(omp_low_lat_mem_alloc),align(4096))]];
+
+#ifndef __cplusplus
+  _Static_assert (_Alignof(AAA) == _Alignof(int), "wrong alignment");
+#elif __cplusplus >= 201103L
+  static_assert (alignof(AAA) == _Alignof(int), "wrong alignment");
+#endif
+
+
+void test0 ()
+{
+  int A1[5], B1;
+  #pragma omp allocate(A1, B1) align(512) allocator(omp_default_mem_alloc)
+
+#ifndef __cplusplus
+  _Static_assert (_Alignof(A1) == _Alignof(int[5]), "wrong alignment");
+  _Static_assert (_Alignof(B1) == _Alignof(int), "wrong alignment");
+#elif __cplusplus >= 201103L
+  static_assert (alignof(A1) == alignof(int[5]), "wrong alignment");
+  static_assert (alignof(B1) == alignof(int), "wrong alignment");
+#endif
+
+  if (((__UINTPTR_TYPE__) &A1 % 512) != 0)
+    __builtin_abort ();
+  if (((__UINTPTR_TYPE__) &B1 % 512) != 0)
+    __builtin_abort ();
+}
+
+int main()
+{
+  static int BBB [[omp::decl(allocate,allocator(omp_low_lat_mem_alloc),align(4096))]];
+
+#ifndef __cplusplus
+  _Static_assert (_Alignof(AAA) == _Alignof(int), "wrong alignment");
+#elif __cplusplus >= 201103L
+  static_assert (alignof(AAA) == alignof(int), "wrong alignment");
+#endif
+
+  if (((__UINTPTR_TYPE__) &AAA % 4096) != 0)
+    __builtin_abort ();
+  if (((__UINTPTR_TYPE__) &BBB % 4096) != 0)
+    __builtin_abort ();
+
+  test0 ();
+
+  return 0;
+}