re PR c++/26943 ([gomp] firstprivate + lastprivate uses inefficient barrier)

	PR c++/26943
	* omp-low.c (maybe_lookup_decl_in_outer_ctx): New function.
	(build_outer_var_ref): Use maybe_lookup_decl_in_outer_ctx
	to find if var will be a global variable even in the nested context.
	(omp_copy_decl): Only check for global variable at the end, it might
	be overridden in outer contexts.
	(scan_sharing_clauses): For global variables don't create a field.
	(lower_rec_input_clauses): Do nothing for global shared variables.
	Emit a barrier at the end of ILIST if there were any decls in both
	firstprivate and lastprivate clauses.
	(lower_send_clauses): Do nothing for global variables except for
	COPYIN.

	* testsuite/libgomp.c/pr26943-1.c: New test.
	* testsuite/libgomp.c/pr26943-2.c: New test.
	* testsuite/libgomp.c/pr26943-3.c: New test.
	* testsuite/libgomp.c/pr26943-4.c: New test.
	* testsuite/libgomp.c++/pr27337.C: Remove barrier.
	* testsuite/libgomp.c++/pr26943.C: New test.

From-SVN: r113483

gcc/ChangeLog

+2006-05-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/26943
+	* omp-low.c (maybe_lookup_decl_in_outer_ctx): New function.
+	(build_outer_var_ref): Use maybe_lookup_decl_in_outer_ctx
+	to find if var will be a global variable even in the nested context.
+	(omp_copy_decl): Only check for global variable at the end, it might
+	be overridden in outer contexts.
+	(scan_sharing_clauses): For global variables don't create a field.
+	(lower_rec_input_clauses): Do nothing for global shared variables.
+	Emit a barrier at the end of ILIST if there were any decls in both
+	firstprivate and lastprivate clauses.
+	(lower_send_clauses): Do nothing for global variables except for
+	COPYIN.
+
 2006-05-02  Zdenek Dvorak <dvorakz@suse.cz>
 
 	* tree.c (unsigned_type_for, signed_type_for): Make sure a type

gcc/omp-low.c

@@ -112,6 +112,8 @@ struct omp_region *root_omp_region;
 
 static void scan_omp (tree *, omp_context *);
 static void lower_omp (tree *, omp_context *);
+static tree lookup_decl_in_outer_ctx (tree, omp_context *);
+static tree maybe_lookup_decl_in_outer_ctx (tree, omp_context *);
 
 /* Find an OpenMP clause of type KIND within CLAUSES.  */
 
@@ -560,7 +562,7 @@ build_outer_var_ref (tree var, omp_context *ctx)
 {
   tree x;
 
-  if (is_global_var (var))
+  if (is_global_var (maybe_lookup_decl_in_outer_ctx (var, ctx)))
     x = var;
   else if (is_variable_sized (var))
     {
@@ -674,9 +676,6 @@ omp_copy_decl (tree var, copy_body_data *cb)
   omp_context *ctx = (omp_context *) cb;
   tree new_var;
 
-  if (is_global_var (var) || decl_function_context (var) != ctx->cb.src_fn)
-    return var;
-
   if (TREE_CODE (var) == LABEL_DECL)
     {
       new_var = create_artificial_label ();
@@ -695,6 +694,9 @@ omp_copy_decl (tree var, copy_body_data *cb)
 	return new_var;
     }
 
+  if (is_global_var (var) || decl_function_context (var) != ctx->cb.src_fn)
+    return var;
+
   return error_mark_node;
 }
 
@@ -937,6 +939,10 @@ scan_sharing_clauses (tree clauses, omp_context *ctx)
 	  decl = OMP_CLAUSE_DECL (c);
 	  gcc_assert (!is_variable_sized (decl));
 	  by_ref = use_pointer_for_field (decl, true);
+	  /* Global variables don't need to be copied,
+	     the receiver side will use them directly.  */
+	  if (is_global_var (maybe_lookup_decl_in_outer_ctx (decl, ctx)))
+	    break;
 	  if (! TREE_READONLY (decl)
 	      || TREE_ADDRESSABLE (decl)
 	      || by_ref
@@ -963,7 +969,9 @@ scan_sharing_clauses (tree clauses, omp_context *ctx)
 	do_private:
 	  if (is_variable_sized (decl))
 	    break;
-	  else if (is_parallel_ctx (ctx))
+	  else if (is_parallel_ctx (ctx)
+		   && ! is_global_var (maybe_lookup_decl_in_outer_ctx (decl,
+								       ctx)))
 	    {
 	      by_ref = use_pointer_for_field (decl, false);
 	      install_var_field (decl, by_ref, ctx);
@@ -1029,7 +1037,8 @@ scan_sharing_clauses (tree clauses, omp_context *ctx)
 
 	case OMP_CLAUSE_SHARED:
 	  decl = OMP_CLAUSE_DECL (c);
-	  fixup_remapped_decl (decl, ctx, false);
+	  if (! is_global_var (maybe_lookup_decl_in_outer_ctx (decl, ctx)))
+	    fixup_remapped_decl (decl, ctx, false);
 	  break;
 
 	case OMP_CLAUSE_COPYPRIVATE:
@@ -1415,6 +1424,23 @@ lookup_decl_in_outer_ctx (tree decl, omp_context *ctx)
 }
 
 
+/* Similar to lookup_decl_in_outer_ctx, but return DECL if not found
+   in outer contexts.  */
+
+static tree
+maybe_lookup_decl_in_outer_ctx (tree decl, omp_context *ctx)
+{
+  tree t = NULL;
+  omp_context *up;
+
+  if (ctx->is_nested)
+    for (up = ctx->outer, t = NULL; up && t == NULL; up = up->outer)
+      t = maybe_lookup_decl (decl, up);
+
+  return t ? t : decl;
+}
+
+
 /* Construct the initialization value for reduction CLAUSE.  */
 
 tree
@@ -1493,6 +1519,7 @@ lower_rec_input_clauses (tree clauses, tree *ilist, tree *dlist,
   tree_stmt_iterator diter;
   tree c, dtor, copyin_seq, x, args, ptr;
   bool copyin_by_ref = false;
+  bool lastprivate_firstprivate = false;
   int pass;
 
   *dlist = alloc_stmt_list ();
@@ -1518,14 +1545,22 @@ lower_rec_input_clauses (tree clauses, tree *ilist, tree *dlist,
 		continue;
 	      break;
 	    case OMP_CLAUSE_SHARED:
+	      if (maybe_lookup_decl (OMP_CLAUSE_DECL (c), ctx) == NULL)
+		{
+		  gcc_assert (is_global_var (OMP_CLAUSE_DECL (c)));
+		  continue;
+		}
 	    case OMP_CLAUSE_FIRSTPRIVATE:
 	    case OMP_CLAUSE_COPYIN:
 	    case OMP_CLAUSE_REDUCTION:
 	      break;
 	    case OMP_CLAUSE_LASTPRIVATE:
-	      if (pass != 0
-		  && OMP_CLAUSE_LASTPRIVATE_FIRSTPRIVATE (c))
-		continue;
+	      if (OMP_CLAUSE_LASTPRIVATE_FIRSTPRIVATE (c))
+		{
+		  lastprivate_firstprivate = true;
+		  if (pass != 0)
+		    continue;
+		}
 	      break;
 	    default:
 	      continue;
@@ -1611,6 +1646,9 @@ lower_rec_input_clauses (tree clauses, tree *ilist, tree *dlist,
 	  switch (OMP_CLAUSE_CODE (c))
 	    {
 	    case OMP_CLAUSE_SHARED:
+	      /* Shared global vars are just accessed directly.  */
+	      if (is_global_var (new_var))
+		break;
 	      /* Set up the DECL_VALUE_EXPR for shared variables now.  This
 		 needs to be delayed until after fixup_child_record_type so
 		 that we get the correct type during the dereference.  */
@@ -1700,8 +1738,10 @@ lower_rec_input_clauses (tree clauses, tree *ilist, tree *dlist,
 
   /* If any copyin variable is passed by reference, we must ensure the
      master thread doesn't modify it before it is copied over in all
-     threads.  */
-  if (copyin_by_ref)
+     threads.  Similarly for variables in both firstprivate and
+     lastprivate clauses we need to ensure the lastprivate copying
+     happens after firstprivate copying in all threads.  */
+  if (copyin_by_ref || lastprivate_firstprivate)
     build_omp_barrier (ilist);
 }
 
@@ -1919,6 +1959,9 @@ lower_send_clauses (tree clauses, tree *ilist, tree *olist, omp_context *ctx)
       if (ctx->is_nested)
 	var = lookup_decl_in_outer_ctx (val, ctx);
 
+      if (OMP_CLAUSE_CODE (c) != OMP_CLAUSE_COPYIN
+	  && is_global_var (var))
+	continue;
       if (is_variable_sized (val))
 	continue;
       by_ref = use_pointer_for_field (val, false);

libgomp/ChangeLog

 2006-05-02  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/26943
+	* testsuite/libgomp.c/pr26943-1.c: New test.
+	* testsuite/libgomp.c/pr26943-2.c: New test.
+	* testsuite/libgomp.c/pr26943-3.c: New test.
+	* testsuite/libgomp.c/pr26943-4.c: New test.
+	* testsuite/libgomp.c++/pr27337.C: Remove barrier.
+	* testsuite/libgomp.c++/pr26943.C: New test.
+
+2006-05-02  Jakub Jelinek  <jakub@redhat.com>
+
 	PR middle-end/27337
 	* testsuite/libgomp.c++/pr27337.C: New test.
 

libgomp/testsuite/libgomp.c++/pr26943.C

+// PR c++/26943
+// { dg-do run }
+
+#include <assert.h>
+#include <unistd.h>
+
+struct S
+{
+  public:
+    int x;
+    S () : x(-1) { }
+    S (const S &);
+    S& operator= (const S &);
+    void test ();
+};
+
+static volatile int hold;
+
+S::S (const S &s)
+{
+  #pragma omp master
+    sleep (1);
+
+  assert (s.x == -1);
+  x = 0;
+}
+
+S&
+S::operator= (const S& s)
+{
+  assert (s.x == 1);
+  x = 2;
+  return *this;
+}
+
+void
+S::test ()
+{
+  assert (x == 0);
+  x = 1;
+}
+
+static S x;
+
+void
+foo ()
+{
+  #pragma omp sections firstprivate(x) lastprivate(x)
+  {
+    x.test();
+  }
+}
+
+int
+main ()
+{
+  #pragma omp parallel num_threads(2)
+    foo();
+
+  assert (x.x == 2);
+  return 0;
+}

libgomp/testsuite/libgomp.c++/pr27337.C

@@ -48,11 +48,7 @@ foo ()
 #pragma omp parallel for firstprivate (ret) lastprivate (ret) \
 			 schedule (static, 1) num_threads (4)
   for (i = 0; i < 4; i++)
-    {
-      ret.i += omp_get_thread_num ();
-      // FIXME: The following barrier should be unnecessary.
-#pragma omp barrier
-    }
+    ret.i += omp_get_thread_num ();
 
   return ret;
 }

libgomp/testsuite/libgomp.c/pr26943-1.c

+/* PR c++/26943 */
+/* { dg-do run } */
+
+extern void abort (void);
+extern void omp_set_dynamic (int);
+int n = 6;
+
+int
+main (void)
+{
+  int i, x = 0;
+  omp_set_dynamic (0);
+#pragma omp parallel for num_threads (16) firstprivate (n) lastprivate (n) \
+			 schedule (static, 1) reduction (+: x)
+  for (i = 0; i < 16; i++)
+    {
+      if (n != 6)
+	++x;
+      n = i;
+    }
+  if (x || n != 15)
+    abort ();
+  return 0;
+}

libgomp/testsuite/libgomp.c/pr26943-2.c

+/* PR c++/26943 */
+/* { dg-do run } */
+
+extern int omp_set_dynamic (int);
+extern void abort (void);
+
+int a = 8, b = 12, c = 16, d = 20, j = 0;
+char e[10] = "a", f[10] = "b", g[10] = "c", h[10] = "d";
+
+int
+main (void)
+{
+  int i;
+  omp_set_dynamic (0);
+#pragma omp parallel for shared (a, e) firstprivate (b, f) \
+			 lastprivate (c, g) private (d, h) \
+			 schedule (static, 1) num_threads (4) \
+			 reduction (+:j)
+  for (i = 0; i < 4; i++)
+    {
+      if (a != 8 || b != 12 || e[0] != 'a' || f[0] != 'b')
+	j++;
+#pragma omp barrier
+#pragma omp atomic
+      a += i;
+      b += i;
+      c = i;
+      d = i;
+#pragma omp atomic
+      e[0] += i;
+      f[0] += i;
+      g[0] = 'g' + i;
+      h[0] = 'h' + i;
+#pragma omp barrier
+      if (a != 8 + 6 || b != 12 + i || c != i || d != i)
+	j += 8;
+      if (e[0] != 'a' + 6 || f[0] != 'b' + i || g[0] != 'g' + i)
+	j += 64;
+      if (h[0] != 'h' + i)
+	j += 512;
+    }
+  if (j || a != 8 + 6 || b != 12 || c != 3 || d != 20)
+    abort ();
+  if (e[0] != 'a' + 6 || f[0] != 'b' || g[0] != 'g' + 3 || h[0] != 'd')
+    abort ();
+  return 0;
+}

libgomp/testsuite/libgomp.c/pr26943-3.c

+/* PR c++/26943 */
+/* { dg-do run } */
+
+extern int omp_set_dynamic (int);
+extern int omp_get_thread_num (void);
+extern void abort (void);
+
+int a = 8, b = 12, c = 16, d = 20, j = 0, l = 0;
+char e[10] = "a", f[10] = "b", g[10] = "c", h[10] = "d";
+volatile int k;
+
+int
+main (void)
+{
+  int i;
+  omp_set_dynamic (0);
+  omp_set_nested (1);
+#pragma omp parallel num_threads (2) reduction (+:l)
+  if (k == omp_get_thread_num ())
+    {
+#pragma omp parallel for shared (a, e) firstprivate (b, f) \
+			 lastprivate (c, g) private (d, h) \
+			 schedule (static, 1) num_threads (4) \
+			 reduction (+:j)
+      for (i = 0; i < 4; i++)
+	{
+	  if (a != 8 || b != 12 || e[0] != 'a' || f[0] != 'b')
+	    j++;
+#pragma omp barrier
+#pragma omp atomic
+	  a += i;
+	  b += i;
+	  c = i;
+	  d = i;
+#pragma omp atomic
+	  e[0] += i;
+	  f[0] += i;
+	  g[0] = 'g' + i;
+	  h[0] = 'h' + i;
+#pragma omp barrier
+	  if (a != 8 + 6 || b != 12 + i || c != i || d != i)
+	    j += 8;
+	  if (e[0] != 'a' + 6 || f[0] != 'b' + i || g[0] != 'g' + i)
+	    j += 64;
+	  if (h[0] != 'h' + i)
+	    j += 512;
+	}
+      if (j || a != 8 + 6 || b != 12 || c != 3 || d != 20)
+	++l;
+      if (e[0] != 'a' + 6 || f[0] != 'b' || g[0] != 'g' + 3 || h[0] != 'd')
+	l += 8;
+    }
+  if (l)
+    abort ();
+  return 0;
+}

libgomp/testsuite/libgomp.c/pr26943-4.c

+/* PR c++/26943 */
+/* { dg-do run } */
+
+extern int omp_set_dynamic (int);
+extern int omp_get_thread_num (void);
+extern void abort (void);
+
+int a = 8, b = 12, c = 16, d = 20, j = 0, l = 0;
+char e[10] = "a", f[10] = "b", g[10] = "c", h[10] = "d";
+volatile int k;
+
+int
+main (void)
+{
+  int i;
+  omp_set_dynamic (0);
+  omp_set_nested (1);
+#pragma omp parallel num_threads (2) reduction (+:l) \
+		     firstprivate (a, b, c, d, e, f, g, h, j)
+  if (k == omp_get_thread_num ())
+    {
+#pragma omp parallel for shared (a, e) firstprivate (b, f) \
+			 lastprivate (c, g) private (d, h) \
+			 schedule (static, 1) num_threads (4) \
+			 reduction (+:j)
+      for (i = 0; i < 4; i++)
+	{
+	  if (a != 8 || b != 12 || e[0] != 'a' || f[0] != 'b')
+	    j++;
+#pragma omp barrier
+#pragma omp atomic
+	  a += i;
+	  b += i;
+	  c = i;
+	  d = i;
+#pragma omp atomic
+	  e[0] += i;
+	  f[0] += i;
+	  g[0] = 'g' + i;
+	  h[0] = 'h' + i;
+#pragma omp barrier
+	  if (a != 8 + 6 || b != 12 + i || c != i || d != i)
+	    j += 8;
+	  if (e[0] != 'a' + 6 || f[0] != 'b' + i || g[0] != 'g' + i)
+	    j += 64;
+	  if (h[0] != 'h' + i)
+	    j += 512;
+	}
+      if (j || a != 8 + 6 || b != 12 || c != 3 || d != 20)
+	++l;
+      if (e[0] != 'a' + 6 || f[0] != 'b' || g[0] != 'g' + 3 || h[0] != 'd')
+	l += 8;
+    }
+  if (l)
+    abort ();
+  if (a != 8 || b != 12 || c != 16 || d != 20)
+    abort ();
+  if (e[0] != 'a' || f[0] != 'b' || g[0] != 'c' || h[0] != 'd')
+    abort ();
+  return 0;
+}