Insert diverging jump alap in nvptx_single

2017-07-17  Tom de Vries  <tom@codesourcery.com>

	PR target/81069
	* config/nvptx/nvptx.c (nvptx_single): Insert diverging branch as late
	as possible.

From-SVN: r250256

gcc/ChangeLog

+2017-07-17  Tom de Vries  <tom@codesourcery.com>
+
+	PR target/81069
+	* config/nvptx/nvptx.c (nvptx_single): Insert diverging branch as late
+	as possible.
+
 2017-07-17  Sebastian Huber  <sebastian.huber@embedded-brains.de>
 
 	*  gcc/config/sparc/rtemself.h (TARGET_OS_CPP_BUILTINS): Add

gcc/config/nvptx/nvptx.c

@@ -3886,9 +3886,25 @@ nvptx_single (unsigned mask, basic_block from, basic_block to)
   rtx_insn *tail = BB_END (to);
   unsigned skip_mask = mask;
 
-  /* Find first insn of from block */
-  while (head != BB_END (from) && !INSN_P (head))
-    head = NEXT_INSN (head);
+  while (true)
+    {
+      /* Find first insn of from block.  */
+      while (head != BB_END (from) && !INSN_P (head))
+	head = NEXT_INSN (head);
+
+      if (from == to)
+	break;
+
+      if (!(JUMP_P (head) && single_succ_p (from)))
+	break;
+
+      basic_block jump_target = single_succ (from);
+      if (!single_pred_p (jump_target))
+	break;
+
+      from = jump_target;
+      head = BB_HEAD (from);
+    }
 
   /* Find last insn of to block */
   rtx_insn *limit = from == to ? head : BB_HEAD (to);