openmp: Fix up handling of reduction clauses on the loop construct [PR102431]

We were using unshare_expr and walk_tree_without_duplicate replacement
of the placeholder vars.  The OMP_CLAUSE_REDUCTION_{INIT,MERGE} can contain
other trees that need to be duplicated though, e.g. BLOCKs referenced in
BIND_EXPR(s), or local VAR_DECLs.  This patch uses the inliner code to copy
all of that.  There is a slight complication that those local VAR_DECLs or
placeholders don't have DECL_CONTEXT set, they will get that only when
they are gimplified later on, so this patch sets DECL_CONTEXT for those
temporarily and resets it afterwards.

2021-11-23  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/102431
	* gimplify.c (replace_reduction_placeholders): Remove.
	(note_no_context_vars): New function.
	(gimplify_omp_loop): For OMP_PARALLEL's BIND_EXPR create a new
	BLOCK.  Use copy_tree_body_r with walk_tree instead of unshare_expr
	and replace_reduction_placeholders for duplication of
	OMP_CLAUSE_REDUCTION_{INIT,MERGE} expressions.  Ensure all mentioned
	automatic vars have DECL_CONTEXT set to non-NULL before doing so
	and reset it afterwards for those vars and their corresponding
	vars.

	* c-c++-common/gomp/pr102431.c: New test.
	* g++.dg/gomp/pr102431.C: New test.
	* gfortran.dg/gomp/pr102431.f90: New test.

4 files changed, 99 insertions, 26 deletions

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 467b1357e85..8e0adbe7484 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -13128,21 +13128,15 @@ gimplify_omp_for (tree *expr_p, gimple_seq *pre_p)
 /* Helper for gimplify_omp_loop, called through walk_tree.  */
 
 static tree
-replace_reduction_placeholders (tree *tp, int *walk_subtrees, void *data)
+note_no_context_vars (tree *tp, int *, void *data)
 {
-  if (DECL_P (*tp))
+  if (VAR_P (*tp)
+      && DECL_CONTEXT (*tp) == NULL_TREE
+      && !is_global_var (*tp))
     {
-      tree *d = (tree *) data;
-      if (*tp == OMP_CLAUSE_REDUCTION_PLACEHOLDER (d[0]))
-	{
-	  *tp = OMP_CLAUSE_REDUCTION_PLACEHOLDER (d[1]);
-	  *walk_subtrees = 0;
-	}
-      else if (*tp == OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (d[0]))
-	{
-	  *tp = OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (d[1]);
-	  *walk_subtrees = 0;
-	}
+      vec<tree> *d = (vec<tree> *) data;
+      d->safe_push (*tp);
+      DECL_CONTEXT (*tp) = current_function_decl;
     }
   return NULL_TREE;
 }
@@ -13312,7 +13306,8 @@ gimplify_omp_loop (tree *expr_p, gimple_seq *pre_p)
     {
       if (pass == 2)
 	{
-	  tree bind = build3 (BIND_EXPR, void_type_node, NULL, NULL, NULL);
+	  tree bind = build3 (BIND_EXPR, void_type_node, NULL, NULL,
+			      make_node (BLOCK));
 	  append_to_statement_list (*expr_p, &BIND_EXPR_BODY (bind));
 	  *expr_p = make_node (OMP_PARALLEL);
 	  TREE_TYPE (*expr_p) = void_type_node;
@@ -13379,25 +13374,64 @@ gimplify_omp_loop (tree *expr_p, gimple_seq *pre_p)
 	    *pc = copy_node (c);
 	    OMP_CLAUSE_DECL (*pc) = unshare_expr (OMP_CLAUSE_DECL (c));
 	    TREE_TYPE (*pc) = unshare_expr (TREE_TYPE (c));
-	    OMP_CLAUSE_REDUCTION_INIT (*pc)
-	      = unshare_expr (OMP_CLAUSE_REDUCTION_INIT (c));
-	    OMP_CLAUSE_REDUCTION_MERGE (*pc)
-	      = unshare_expr (OMP_CLAUSE_REDUCTION_MERGE (c));
 	    if (OMP_CLAUSE_REDUCTION_PLACEHOLDER (*pc))
 	      {
+		auto_vec<tree> no_context_vars;
+		int walk_subtrees = 0;
+		note_no_context_vars (&OMP_CLAUSE_REDUCTION_PLACEHOLDER (c),
+				      &walk_subtrees, &no_context_vars);
+		if (tree p = OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (c))
+		  note_no_context_vars (&p, &walk_subtrees, &no_context_vars);
+		walk_tree_without_duplicates (&OMP_CLAUSE_REDUCTION_INIT (c),
+					      note_no_context_vars,
+					      &no_context_vars);
+		walk_tree_without_duplicates (&OMP_CLAUSE_REDUCTION_MERGE (c),
+					      note_no_context_vars,
+					      &no_context_vars);
+
 		OMP_CLAUSE_REDUCTION_PLACEHOLDER (*pc)
 		  = copy_node (OMP_CLAUSE_REDUCTION_PLACEHOLDER (c));
 		if (OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (*pc))
 		  OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (*pc)
 		    = copy_node (OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (c));
-		tree nc = *pc;
-		tree data[2] = { c, nc };
-		walk_tree_without_duplicates (&OMP_CLAUSE_REDUCTION_INIT (nc),
-					      replace_reduction_placeholders,
-					      data);
-		walk_tree_without_duplicates (&OMP_CLAUSE_REDUCTION_MERGE (nc),
-					      replace_reduction_placeholders,
-					      data);
+
+		hash_map<tree, tree> decl_map;
+		decl_map.put (OMP_CLAUSE_DECL (c), OMP_CLAUSE_DECL (c));
+		decl_map.put (OMP_CLAUSE_REDUCTION_PLACEHOLDER (c),
+			      OMP_CLAUSE_REDUCTION_PLACEHOLDER (*pc));
+		if (OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (*pc))
+		  decl_map.put (OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (c),
+				OMP_CLAUSE_REDUCTION_DECL_PLACEHOLDER (*pc));
+
+		copy_body_data id;
+		memset (&id, 0, sizeof (id));
+		id.src_fn = current_function_decl;
+		id.dst_fn = current_function_decl;
+		id.src_cfun = cfun;
+		id.decl_map = &decl_map;
+		id.copy_decl = copy_decl_no_change;
+		id.transform_call_graph_edges = CB_CGE_DUPLICATE;
+		id.transform_new_cfg = true;
+		id.transform_return_to_modify = false;
+		id.transform_lang_insert_block = NULL;
+		id.eh_lp_nr = 0;
+		walk_tree (&OMP_CLAUSE_REDUCTION_INIT (*pc), copy_tree_body_r,
+			   &id, NULL);
+		walk_tree (&OMP_CLAUSE_REDUCTION_MERGE (*pc), copy_tree_body_r,
+			   &id, NULL);
+
+		for (tree d : no_context_vars)
+		  {
+		    DECL_CONTEXT (d) = NULL_TREE;
+		    DECL_CONTEXT (*decl_map.get (d)) = NULL_TREE;
+		  }
+	      }
+	    else
+	      {
+		OMP_CLAUSE_REDUCTION_INIT (*pc)
+		  = unshare_expr (OMP_CLAUSE_REDUCTION_INIT (c));
+		OMP_CLAUSE_REDUCTION_MERGE (*pc)
+		  = unshare_expr (OMP_CLAUSE_REDUCTION_MERGE (c));
 	      }
 	    pc = &OMP_CLAUSE_CHAIN (*pc);
 	    break;
diff --git a/gcc/testsuite/c-c++-common/gomp/pr102431.c b/gcc/testsuite/c-c++-common/gomp/pr102431.c
new file mode 100644
index 00000000000..bf4f3cb71b3
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/pr102431.c
@@ -0,0 +1,16 @@
+/* PR middle-end/102431 */
+
+struct S { int s; } s;
+void add (struct S *, struct S *);
+void init (struct S *);
+void bar (int i, struct S *);
+#pragma omp declare reduction (+:struct S:add (&omp_out, &omp_in)) initializer (init (&omp_priv))
+
+void
+foo (void)
+{
+  int i;
+  #pragma omp loop bind(teams) reduction(+:s)
+  for (i = 0; i < 8; i++)
+    bar (i, &s);
+}
diff --git a/gcc/testsuite/g++.dg/gomp/pr102431.C b/gcc/testsuite/g++.dg/gomp/pr102431.C
new file mode 100644
index 00000000000..7db36f48540
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/pr102431.C
@@ -0,0 +1,13 @@
+// PR middle-end/102431
+
+struct S { S (); ~S (); S (const S &); void add (const S &); int s; } s;
+void bar (int, S &);
+#pragma omp declare reduction (+:S:omp_out.add (omp_in))
+
+void
+foo ()
+{
+  #pragma omp loop bind(teams) reduction(+:s)
+  for (int i = 0; i < 8; i++)
+    bar (i, s);
+}
diff --git a/gcc/testsuite/gfortran.dg/gomp/pr102431.f90 b/gcc/testsuite/gfortran.dg/gomp/pr102431.f90
new file mode 100644
index 00000000000..71efed80d24
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/pr102431.f90
@@ -0,0 +1,10 @@
+! PR middle-end/102431
+
+program pr102431
+  integer :: a(2)
+  a(:) = 0
+  !$omp parallel loop reduction(+:a)
+  do i = 1, 8
+    a = a + 1
+  end do
+end