Add OpenACC 2.6 `serial' construct support

    The `serial' construct (cf. section 2.5.3 of the OpenACC 2.6 standard)
    is equivalent to a `parallel' construct with clauses `num_gangs(1)
    num_workers(1) vector_length(1)' implied.
    These clauses are therefore not supported with the `serial'
    construct. All the remaining clauses accepted with `parallel' are also
    accepted with `serial'.

    The `serial' construct is implemented like `parallel', except for
    hardcoding dimensions rather than taking them from the relevant
    clauses, in `expand_omp_target'.

    Separate codes are used to denote the `serial' construct throughout the
    middle end, even though the mapping of `serial' to an equivalent
    `parallel' construct could have been done in the individual language
    frontends. In particular, this allows to distinguish between compute
    constructs in warnings, error messages, dumps etc.

    2019-11-12  Maciej W. Rozycki  <macro@codesourcery.com>
                Tobias Burnus  <tobias@codesourcery.com>
                Frederik Harwath  <frederik@codesourcery.com>
                Thomas Schwinge  <thomas@codesourcery.com>

    gcc/
    * gimple.h (gf_mask): Add GF_OMP_TARGET_KIND_OACC_SERIAL
    enumeration constant.
    (is_gimple_omp_oacc): Handle GF_OMP_TARGET_KIND_OACC_SERIAL.
    (is_gimple_omp_offloaded): Likewise.
    * gimplify.c (omp_region_type): Add ORT_ACC_SERIAL enumeration
    constant.  Adjust the value of ORT_NONE accordingly.
    (is_gimple_stmt): Handle OACC_SERIAL.
    (oacc_default_clause): Handle ORT_ACC_SERIAL.
    (gomp_needs_data_present): Likewise.
    (gimplify_adjust_omp_clauses): Likewise.
    (gimplify_omp_workshare): Handle OACC_SERIAL.
    (gimplify_expr): Likewise.
    * omp-expand.c (expand_omp_target):
    Handle GF_OMP_TARGET_KIND_OACC_SERIAL.
    (build_omp_regions_1, omp_make_gimple_edges): Likewise.
    * omp-low.c (is_oacc_parallel): Rename function to...
    (is_oacc_parallel_or_serial): ... this.
    Handle GF_OMP_TARGET_KIND_OACC_SERIAL.
    (scan_sharing_clauses): Adjust accordingly.
    (scan_omp_for): Likewise.
    (lower_oacc_head_mark): Likewise.
    (convert_from_firstprivate_int): Likewise.
    (lower_omp_target): Likewise.
    (check_omp_nesting_restrictions): Handle
    GF_OMP_TARGET_KIND_OACC_SERIAL.
    (lower_oacc_reductions): Likewise.
    (lower_omp_target): Likewise.
    * tree.def (OACC_SERIAL): New tree code.
    * tree-pretty-print.c (dump_generic_node): Handle OACC_SERIAL.

    * doc/generic.texi (OpenACC): Document OACC_SERIAL.

    gcc/c-family/
    * c-pragma.h (pragma_kind): Add PRAGMA_OACC_SERIAL enumeration
    constant.
    * c-pragma.c (oacc_pragmas): Add "serial" entry.

    gcc/c/
    * c-parser.c (OACC_SERIAL_CLAUSE_MASK): New macro.
    (c_parser_oacc_kernels_parallel): Rename function to...
    (c_parser_oacc_compute): ... this.  Handle PRAGMA_OACC_SERIAL.
    (c_parser_omp_construct): Update accordingly.

    gcc/cp/
    * constexpr.c (potential_constant_expression_1): Handle
    OACC_SERIAL.
    * parser.c (OACC_SERIAL_CLAUSE_MASK): New macro.
    (cp_parser_oacc_kernels_parallel): Rename function to...
    (cp_parser_oacc_compute): ... this.  Handle PRAGMA_OACC_SERIAL.
    (cp_parser_omp_construct): Update accordingly.
    (cp_parser_pragma): Handle PRAGMA_OACC_SERIAL.  Fix alphabetic
    order.
    * pt.c (tsubst_expr): Handle OACC_SERIAL.

    gcc/fortran/
    * gfortran.h (gfc_statement): Add ST_OACC_SERIAL_LOOP,
    ST_OACC_END_SERIAL_LOOP, ST_OACC_SERIAL and ST_OACC_END_SERIAL
    enumeration constants.
    (gfc_exec_op): Add EXEC_OACC_SERIAL_LOOP and EXEC_OACC_SERIAL
    enumeration constants.
    * match.h (gfc_match_oacc_serial): New prototype.
    (gfc_match_oacc_serial_loop): Likewise.
    * dump-parse-tree.c (show_omp_node, show_code_node): Handle
    EXEC_OACC_SERIAL_LOOP and EXEC_OACC_SERIAL.
    * match.c (match_exit_cycle): Handle EXEC_OACC_SERIAL_LOOP.
    * openmp.c (OACC_SERIAL_CLAUSES): New macro.
    (gfc_match_oacc_serial_loop): New function.
    (gfc_match_oacc_serial): Likewise.
    (oacc_is_loop): Handle EXEC_OACC_SERIAL_LOOP.
    (resolve_omp_clauses): Handle EXEC_OACC_SERIAL.
    (oacc_code_to_statement): Handle EXEC_OACC_SERIAL and
    EXEC_OACC_SERIAL_LOOP.
    (gfc_resolve_oacc_directive): Likewise.
    * parse.c (decode_oacc_directive) <'s'>: Add case for "serial"
    and "serial loop".
    (next_statement): Handle ST_OACC_SERIAL_LOOP and ST_OACC_SERIAL.
    (gfc_ascii_statement): Likewise.  Handle ST_OACC_END_SERIAL_LOOP
    and ST_OACC_END_SERIAL.
    (parse_oacc_structured_block): Handle ST_OACC_SERIAL.
    (parse_oacc_loop): Handle ST_OACC_SERIAL_LOOP and
    ST_OACC_END_SERIAL_LOOP.
    (parse_executable): Handle ST_OACC_SERIAL_LOOP and
    ST_OACC_SERIAL.
    (is_oacc): Handle EXEC_OACC_SERIAL_LOOP and EXEC_OACC_SERIAL.
    * resolve.c (gfc_resolve_blocks, gfc_resolve_code): Likewise.
    * st.c (gfc_free_statement): Likewise.
    * trans-openmp.c (gfc_trans_oacc_construct): Handle
    EXEC_OACC_SERIAL.
    (gfc_trans_oacc_combined_directive): Handle
    EXEC_OACC_SERIAL_LOOP.
    (gfc_trans_oacc_directive): Handle EXEC_OACC_SERIAL_LOOP and
    EXEC_OACC_SERIAL.
    * trans.c (trans_code): Likewise.

    gcc/testsuite/
    * c-c++-common/goacc/parallel-dims.c: New test.
    * gfortran.dg/goacc/parallel-dims.f90: New test.

    libgomp/
    * testsuite/libgomp.oacc-c-c++-common/parallel-dims.c: New test.
    * testsuite/libgomp.oacc-fortran/parallel-dims-aux.c: New test.
    * testsuite/libgomp.oacc-fortran/parallel-dims.f89: New test.
    * testsuite/libgomp.oacc-fortran/parallel-dims-2.f90: New test.

Reviewed-by: Thomas Schwinge <thomas@codesourcery.com>


Co-Authored-By: Frederik Harwath <frederik@codesourcery.com>
Co-Authored-By: Thomas Schwinge <thomas@codesourcery.com>
Co-Authored-By: Tobias Burnus <tobias@codesourcery.com>

From-SVN: r278082

1 files changed, 24 insertions, 14 deletions

diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index e232d7a..781e7cb 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -185,15 +185,18 @@ static tree scan_omp_1_op (tree *, int *, void *);
       *handled_ops_p = false; \
       break;
 
-/* Return true if CTX corresponds to an oacc parallel region.  */
+/* Return true if CTX corresponds to an OpenACC 'parallel' or 'serial'
+   region.  */
 
 static bool
-is_oacc_parallel (omp_context *ctx)
+is_oacc_parallel_or_serial (omp_context *ctx)
 {
   enum gimple_code outer_type = gimple_code (ctx->stmt);
   return ((outer_type == GIMPLE_OMP_TARGET)
-	  && (gimple_omp_target_kind (ctx->stmt)
-	      == GF_OMP_TARGET_KIND_OACC_PARALLEL));
+	  && ((gimple_omp_target_kind (ctx->stmt)
+	       == GF_OMP_TARGET_KIND_OACC_PARALLEL)
+	      || (gimple_omp_target_kind (ctx->stmt)
+		  == GF_OMP_TARGET_KIND_OACC_SERIAL)));
 }
 
 /* Return true if CTX corresponds to an oacc kernels region.  */
@@ -1149,7 +1152,7 @@ scan_sharing_clauses (tree clauses, omp_context *ctx)
 	  goto do_private;
 
 	case OMP_CLAUSE_REDUCTION:
-	  if (is_oacc_parallel (ctx) || is_oacc_kernels (ctx))
+	  if (is_oacc_parallel_or_serial (ctx) || is_oacc_kernels (ctx))
 	    ctx->local_reduction_clauses
 	      = tree_cons (NULL, c, ctx->local_reduction_clauses);
 	  /* FALLTHRU */
@@ -2391,7 +2394,7 @@ scan_omp_for (gomp_for *stmt, omp_context *outer_ctx)
     {
       omp_context *tgt = enclosing_target_ctx (outer_ctx);
 
-      if (!tgt || is_oacc_parallel (tgt))
+      if (!tgt || is_oacc_parallel_or_serial (tgt))
 	for (tree c = clauses; c; c = OMP_CLAUSE_CHAIN (c))
 	  {
 	    char const *check = NULL;
@@ -2417,7 +2420,7 @@ scan_omp_for (gomp_for *stmt, omp_context *outer_ctx)
 	    if (check && OMP_CLAUSE_OPERAND (c, 0))
 	      error_at (gimple_location (stmt),
 			"argument not permitted on %qs clause in"
-			" OpenACC %<parallel%>", check);
+			" OpenACC %<parallel%> or %<serial%>", check);
 	  }
 
       if (tgt && is_oacc_kernels (tgt))
@@ -2945,6 +2948,7 @@ check_omp_nesting_restrictions (gimple *stmt, omp_context *ctx)
 		  {
 		  case GF_OMP_TARGET_KIND_OACC_PARALLEL:
 		  case GF_OMP_TARGET_KIND_OACC_KERNELS:
+		  case GF_OMP_TARGET_KIND_OACC_SERIAL:
 		    ok = true;
 		    break;
 
@@ -3393,6 +3397,7 @@ check_omp_nesting_restrictions (gimple *stmt, omp_context *ctx)
 	      stmt_name = "target exit data"; break;
 	    case GF_OMP_TARGET_KIND_OACC_PARALLEL: stmt_name = "parallel"; break;
 	    case GF_OMP_TARGET_KIND_OACC_KERNELS: stmt_name = "kernels"; break;
+	    case GF_OMP_TARGET_KIND_OACC_SERIAL: stmt_name = "serial"; break;
 	    case GF_OMP_TARGET_KIND_OACC_DATA: stmt_name = "data"; break;
 	    case GF_OMP_TARGET_KIND_OACC_UPDATE: stmt_name = "update"; break;
 	    case GF_OMP_TARGET_KIND_OACC_ENTER_EXIT_DATA:
@@ -3410,6 +3415,8 @@ check_omp_nesting_restrictions (gimple *stmt, omp_context *ctx)
 	      ctx_stmt_name = "parallel"; break;
 	    case GF_OMP_TARGET_KIND_OACC_KERNELS:
 	      ctx_stmt_name = "kernels"; break;
+	    case GF_OMP_TARGET_KIND_OACC_SERIAL:
+	      ctx_stmt_name = "serial"; break;
 	    case GF_OMP_TARGET_KIND_OACC_DATA: ctx_stmt_name = "data"; break;
 	    case GF_OMP_TARGET_KIND_OACC_HOST_DATA:
 	      ctx_stmt_name = "host_data"; break;
@@ -6711,8 +6718,10 @@ lower_oacc_reductions (location_t loc, tree clauses, tree level, bool inner,
 		    break;
 
 		  case GIMPLE_OMP_TARGET:
-		    if (gimple_omp_target_kind (probe->stmt)
-			!= GF_OMP_TARGET_KIND_OACC_PARALLEL)
+		    if ((gimple_omp_target_kind (probe->stmt)
+			 != GF_OMP_TARGET_KIND_OACC_PARALLEL)
+			&& (gimple_omp_target_kind (probe->stmt)
+			    != GF_OMP_TARGET_KIND_OACC_SERIAL))
 		      goto do_lookup;
 
 		    cls = gimple_omp_target_clauses (probe->stmt);
@@ -7518,7 +7527,7 @@ lower_oacc_head_mark (location_t loc, tree ddvar, tree clauses,
 
   /* In a parallel region, loops are implicitly INDEPENDENT.  */
   omp_context *tgt = enclosing_target_ctx (ctx);
-  if (!tgt || is_oacc_parallel (tgt))
+  if (!tgt || is_oacc_parallel_or_serial (tgt))
     tag |= OLF_INDEPENDENT;
 
   if (tag & OLF_TILE)
@@ -11357,6 +11366,7 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
     case GF_OMP_TARGET_KIND_EXIT_DATA:
     case GF_OMP_TARGET_KIND_OACC_PARALLEL:
     case GF_OMP_TARGET_KIND_OACC_KERNELS:
+    case GF_OMP_TARGET_KIND_OACC_SERIAL:
     case GF_OMP_TARGET_KIND_OACC_UPDATE:
     case GF_OMP_TARGET_KIND_OACC_ENTER_EXIT_DATA:
     case GF_OMP_TARGET_KIND_OACC_DECLARE:
@@ -11489,7 +11499,7 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 	if (!maybe_lookup_field (var, ctx))
 	  continue;
 
-	/* Don't remap oacc parallel reduction variables, because the
+	/* Don't remap compute constructs' reduction variables, because the
 	   intermediate result must be local to each gang.  */
 	if (offloaded && !(OMP_CLAUSE_CODE (c) == OMP_CLAUSE_MAP
 			   && OMP_CLAUSE_MAP_IN_REDUCTION (c)))
@@ -11531,7 +11541,7 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 	break;
 
       case OMP_CLAUSE_FIRSTPRIVATE:
-	if (is_oacc_parallel (ctx))
+	if (is_oacc_parallel_or_serial (ctx))
 	  goto oacc_firstprivate;
 	map_cnt++;
 	var = OMP_CLAUSE_DECL (c);
@@ -11905,7 +11915,7 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 	    break;
 
 	  case OMP_CLAUSE_FIRSTPRIVATE:
-	    if (is_oacc_parallel (ctx))
+	    if (is_oacc_parallel_or_serial (ctx))
 	      goto oacc_firstprivate_map;
 	    ovar = OMP_CLAUSE_DECL (c);
 	    if (omp_is_reference (ovar))
@@ -12509,7 +12519,7 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
       gimple_seq fork_seq = NULL;
       gimple_seq join_seq = NULL;
 
-      if (is_oacc_parallel (ctx))
+      if (is_oacc_parallel_or_serial (ctx))
 	{
 	  /* If there are reductions on the offloaded region itself, treat
 	     them as a dummy GANG loop.  */