[og9] OpenACC assumed-size arrays with non-lexical data mappings

From 2c5a7e445ebadc920730c732279732d2f9b40598 Mon Sep 17 00:00:00 2001
From: Julian Brown <julian@codesourcery.com>
Date: Thu, 4 Jul 2019 18:14:41 -0700
Subject: [PATCH 2/3] Assumed-size arrays with non-lexical data mappings

	gcc/fortran/
	* trans-openmp.c (gfc_omp_finish_clause): Change clauses mapping
	assumed-size arrays to use the GOMP_MAP_FORCE_PRESENT map type.
	* gimplify.c (gimplify_adjust_omp_clauses_1): Raise error for
	assumed-size arrays in map clauses for Fortran/OpenMP.
	* omp-low.c (lower_omp_target): Set the size of assumed-size Fortran
	arrays to one to allow use of data already mapped on the offload device.
---
 gcc/fortran/ChangeLog.openacc |  9 +++++++++
 gcc/fortran/trans-openmp.c    | 22 +++++++++++++---------
 gcc/gimplify.c                | 14 ++++++++++++++
 gcc/omp-low.c                 |  5 +++++
 4 files changed, 41 insertions(+), 9 deletions(-)

diff --git a/gcc/fortran/ChangeLog.openacc b/gcc/fortran/ChangeLog.openacc
index c44a5ebdb3b..beba7d94ad2 100644
--- a/gcc/fortran/ChangeLog.openacc
+++ b/gcc/fortran/ChangeLog.openacc
@@ -1,3 +1,12 @@ 
+2019-07-10  Julian Brown  <julian@codesourcery.com>
+
+	* trans-openmp.c (gfc_omp_finish_clause): Change clauses mapping
+	assumed-size arrays to use the GOMP_MAP_FORCE_PRESENT map type.
+	* gimplify.c (gimplify_adjust_omp_clauses_1): Raise error for
+	assumed-size arrays in map clauses for Fortran/OpenMP.
+	* omp-low.c (lower_omp_target): Set the size of assumed-size Fortran
+	arrays to one to allow use of data already mapped on the offload device.
+
 2019-07-10  Julian Brown  <julian@codesourcery.com>
 
 	* openmp.c (resolve_oacc_data_clauses): Allow polymorphic allocatable
diff --git a/gcc/fortran/trans-openmp.c b/gcc/fortran/trans-openmp.c
index d5ae0b717df..db009130c85 100644
--- a/gcc/fortran/trans-openmp.c
+++ b/gcc/fortran/trans-openmp.c
@@ -1137,10 +1137,18 @@  gfc_omp_finish_clause (tree c, gimple_seq *pre_p)
   tree decl = OMP_CLAUSE_DECL (c);
 
   /* Assumed-size arrays can't be mapped implicitly, they have to be mapped
-     explicitly using array sections.  An exception is if the array is
-     mapped explicitly in an enclosing data construct for OpenACC, in which
-     case we see GOMP_MAP_FORCE_PRESENT here and do not need to raise an
-     error.  */
+     explicitly using array sections.  For OpenACC this restriction is lifted
+     if the array has already been mapped:
+
+       - Using a lexically-enclosing data region: in that case we see the
+         GOMP_MAP_FORCE_PRESENT mapping kind here.
+
+       - Using a non-lexical data mapping ("acc enter data").
+
+     In the latter case we change the mapping type to GOMP_MAP_FORCE_PRESENT.
+     This raises an error for OpenMP in our the caller
+     (gimplify.c:gimplify_adjust_omp_clauses_1).  OpenACC will raise a runtime
+     error if the assumed-size array is not mapped.  */
   if (OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_FORCE_PRESENT
       && TREE_CODE (decl) == PARM_DECL
       && GFC_ARRAY_TYPE_P (TREE_TYPE (decl))
@@ -1148,11 +1156,7 @@  gfc_omp_finish_clause (tree c, gimple_seq *pre_p)
       && GFC_TYPE_ARRAY_UBOUND (TREE_TYPE (decl),
 				GFC_TYPE_ARRAY_RANK (TREE_TYPE (decl)) - 1)
 	 == NULL)
-    {
-      error_at (OMP_CLAUSE_LOCATION (c),
-		"implicit mapping of assumed size array %qD", decl);
-      return;
-    }
+    OMP_CLAUSE_SET_MAP_KIND (c, GOMP_MAP_FORCE_PRESENT);
 
   tree c2 = NULL_TREE, c3 = NULL_TREE, c4 = NULL_TREE;
   if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_FORCE_DEVICEPTR)
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 60e04ff8353..58142c9eb90 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -10088,7 +10088,21 @@  gimplify_adjust_omp_clauses_1 (splay_tree_node n, void *data)
   *list_p = clause;
   struct gimplify_omp_ctx *ctx = gimplify_omp_ctxp;
   gimplify_omp_ctxp = ctx->outer_context;
+  gomp_map_kind kind = (code == OMP_CLAUSE_MAP) ? OMP_CLAUSE_MAP_KIND (clause)
+						: (gomp_map_kind) GOMP_MAP_LAST;
   lang_hooks.decls.omp_finish_clause (clause, pre_p);
+  /* Allow OpenACC to have implicit assumed-size arrays via FORCE_PRESENT,
+     which should work as long as the array has previously been mapped
+     explicitly on the target (e.g. by "enter data").  Raise an error for
+     OpenMP.  */
+  if (lang_GNU_Fortran ()
+      && code == OMP_CLAUSE_MAP
+      && (ctx->region_type & ORT_ACC) == 0
+      && kind == GOMP_MAP_TOFROM
+      && OMP_CLAUSE_MAP_KIND (clause) == GOMP_MAP_FORCE_PRESENT)
+    error_at (OMP_CLAUSE_LOCATION (clause),
+	      "implicit mapping of assumed size array %qD",
+	      OMP_CLAUSE_DECL (clause));
   if (gimplify_omp_ctxp)
     for (; clause != chain; clause = OMP_CLAUSE_CHAIN (clause))
       if (OMP_CLAUSE_CODE (clause) == OMP_CLAUSE_MAP
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 249cc1aac53..97c00217d9f 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -10453,6 +10453,11 @@  lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 	      s = OMP_CLAUSE_SIZE (c);
 	    if (s == NULL_TREE)
 	      s = TYPE_SIZE_UNIT (TREE_TYPE (ovar));
+	    /* Fortran assumed-size arrays have zero size because the type is
+	       incomplete.  Set the size to one to allow the runtime to remap
+	       any existing data that is already present on the accelerator.  */
+	    if (s == NULL_TREE && is_gimple_omp_oacc (ctx->stmt))
+	      s = integer_one_node;
 	    s = fold_convert (size_type_node, s);
 	    decl_args = append_decl_arg (ovar, decl_args, ctx);
 	    purpose = size_int (map_idx++);
-- 
2.22.0