re PR middle-end/66133 (Wrong-code with noreturn #pragma omp task body)

PR middle-end/66133
	* omp-low.c (expand_omp_taskreg): For GIMPLE_OMP_TASK expansion,
	make sure it is never noreturn, even when the task body does not
	return.
	(lower_omp_taskreg): For GIMPLE_OMP_TASK, emit GIMPLE_OMP_CONTINUE
	right before GIMPLE_OMP_RETURN.
	(make_gimple_omp_edges): Accept GIMPLE_OMP_CONTINUE as ->cont
	for GIMPLE_OMP_TASK.  For GIMPLE_OMP_RETURN corresponding to
	GIMPLE_OMP_TASK add an EDGE_ABNORMAL edge from entry to exit.

	* testsuite/libgomp.c/pr66133.c: New test.

From-SVN: r223171

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2015-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/66133
+	* omp-low.c (expand_omp_taskreg): For GIMPLE_OMP_TASK expansion,
+	make sure it is never noreturn, even when the task body does not
+	return.
+	(lower_omp_taskreg): For GIMPLE_OMP_TASK, emit GIMPLE_OMP_CONTINUE
+	right before GIMPLE_OMP_RETURN.
+	(make_gimple_omp_edges): Accept GIMPLE_OMP_CONTINUE as ->cont
+	for GIMPLE_OMP_TASK.  For GIMPLE_OMP_RETURN corresponding to
+	GIMPLE_OMP_TASK add an EDGE_ABNORMAL edge from entry to exit.
+
 2015-05-13  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* params.def (PARAM_MAX_POW_SQRT_DEPTH): New param.

gcc/omp-low.c

@@ -5377,7 +5377,10 @@ expand_omp_taskreg (struct omp_region *region)
   child_cfun = DECL_STRUCT_FUNCTION (child_fn);
 
   entry_bb = region->entry;
-  exit_bb = region->exit;
+  if (gimple_code (entry_stmt) == GIMPLE_OMP_TASK)
+    exit_bb = region->cont;
+  else
+    exit_bb = region->exit;
 
   bool is_cilk_for
     = (flag_cilkplus
@@ -5436,7 +5439,9 @@ expand_omp_taskreg (struct omp_region *region)
 	 variable.  In which case, we need to keep the assignment.  */
       if (gimple_omp_taskreg_data_arg (entry_stmt))
 	{
-	  basic_block entry_succ_bb = single_succ (entry_bb);
+	  basic_block entry_succ_bb
+	    = single_succ_p (entry_bb) ? single_succ (entry_bb)
+				       : FALLTHRU_EDGE (entry_bb)->dest;
 	  tree arg, narg;
 	  gimple parcopy_stmt = NULL;
 
@@ -5524,14 +5529,28 @@ expand_omp_taskreg (struct omp_region *region)
       e = split_block (entry_bb, stmt);
       gsi_remove (&gsi, true);
       entry_bb = e->dest;
-      single_succ_edge (entry_bb)->flags = EDGE_FALLTHRU;
+      edge e2 = NULL;
+      if (gimple_code (entry_stmt) == GIMPLE_OMP_PARALLEL)
+	single_succ_edge (entry_bb)->flags = EDGE_FALLTHRU;
+      else
+	{
+	  e2 = make_edge (e->src, BRANCH_EDGE (entry_bb)->dest, EDGE_ABNORMAL);
+	  gcc_assert (e2->dest == region->exit);
+	  remove_edge (BRANCH_EDGE (entry_bb));
+	  set_immediate_dominator (CDI_DOMINATORS, e2->dest, e->src);
+	  gsi = gsi_last_bb (region->exit);
+	  gcc_assert (!gsi_end_p (gsi)
+		      && gimple_code (gsi_stmt (gsi)) == GIMPLE_OMP_RETURN);
+	  gsi_remove (&gsi, true);
+	}
 
-      /* Convert GIMPLE_OMP_RETURN into a RETURN_EXPR.  */
+      /* Convert GIMPLE_OMP_{RETURN,CONTINUE} into a RETURN_EXPR.  */
       if (exit_bb)
 	{
 	  gsi = gsi_last_bb (exit_bb);
 	  gcc_assert (!gsi_end_p (gsi)
-		      && gimple_code (gsi_stmt (gsi)) == GIMPLE_OMP_RETURN);
+		      && (gimple_code (gsi_stmt (gsi))
+			  == (e2 ? GIMPLE_OMP_CONTINUE : GIMPLE_OMP_RETURN)));
 	  stmt = gimple_build_return (NULL);
 	  gsi_insert_after (&gsi, stmt, GSI_SAME_STMT);
 	  gsi_remove (&gsi, true);
@@ -5552,6 +5571,14 @@ expand_omp_taskreg (struct omp_region *region)
       new_bb = move_sese_region_to_fn (child_cfun, entry_bb, exit_bb, block);
       if (exit_bb)
 	single_succ_edge (new_bb)->flags = EDGE_FALLTHRU;
+      if (e2)
+	{
+	  basic_block dest_bb = e2->dest;
+	  if (!exit_bb)
+	    make_edge (new_bb, dest_bb, EDGE_FALLTHRU);
+	  remove_edge (e2);
+	  set_immediate_dominator (CDI_DOMINATORS, dest_bb, new_bb);
+	}
       /* When the OMP expansion process cannot guarantee an up-to-date
          loop tree arrange for the child function to fixup loops.  */
       if (loops_state_satisfies_p (LOOPS_NEED_FIXUP))
@@ -11158,6 +11185,10 @@ lower_omp_taskreg (gimple_stmt_iterator *gsi_p, omp_context *ctx)
     gimple_seq_add_stmt (&new_body, gimple_build_label (ctx->cancel_label));
   gimple_seq_add_seq (&new_body, par_olist);
   new_body = maybe_catch_exception (new_body);
+  if (gimple_code (stmt) == GIMPLE_OMP_TASK)
+    gimple_seq_add_stmt (&new_body,
+			 gimple_build_omp_continue (integer_zero_node,
+						    integer_zero_node));
   gimple_seq_add_stmt (&new_body, gimple_build_omp_return (false));
   gimple_omp_set_body (stmt, new_body);
 
@@ -12272,6 +12303,10 @@ make_gimple_omp_edges (basic_block bb, struct omp_region **region,
 	 somewhere other than the next block.  This will be
 	 created later.  */
       cur_region->exit = bb;
+      if (cur_region->type == GIMPLE_OMP_TASK)
+	/* Add an edge corresponding to not scheduling the task
+	   immediately.  */
+	make_edge (cur_region->entry, bb, EDGE_ABNORMAL);
       fallthru = cur_region->type != GIMPLE_OMP_SECTION;
       cur_region = cur_region->outer;
       break;
@@ -12320,6 +12355,10 @@ make_gimple_omp_edges (basic_block bb, struct omp_region **region,
 	  }
 	  break;
 
+	case GIMPLE_OMP_TASK:
+	  fallthru = true;
+	  break;
+
 	default:
 	  gcc_unreachable ();
 	}

libgomp/ChangeLog

@@ -1,3 +1,8 @@
+2015-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/66133
+	* testsuite/libgomp.c/pr66133.c: New test.
+
 2015-05-13  Michael Haubenwallner  <michael.haubenwallner@ssi-schaefer.com>
 
 	* Makefile.in: Regenerated with automake-1.11.6.

libgomp/testsuite/libgomp.c/pr66133.c

@@ -0,0 +1,35 @@
+/* PR middle-end/66133 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fopenmp" } */
+
+#include <stdlib.h>
+#include <unistd.h>
+
+volatile int x;
+
+__attribute__((noinline)) void
+foo (void)
+{
+  if (x == 0)
+    {
+      #pragma omp task
+	{
+	  usleep (2000);
+	  exit (0);
+	}
+    }
+  else
+    abort ();
+}
+
+int
+main ()
+{
+  #pragma omp parallel num_threads (2)
+    {
+      #pragma omp barrier
+      #pragma omp single
+	foo ();
+    }
+  exit (0);
+}