[lto] Fixup loops before lto write-out

2018-04-23  Richard Biener <rguenther@suse.de>
	    Tom de Vries  <tom@codesourcery.com>

	PR lto/85422
	* lto-streamer-out.c (output_function): Fixup loops if required to match
	discovery done in the reader.

	* testsuite/libgomp.oacc-c-c++-common/pr85422.c: New test.

---
 gcc/lto-streamer-out.c                                |  4 ++++
 libgomp/testsuite/libgomp.oacc-c-c++-common/pr85422.c | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index 1d2ab97..70476dc 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -2120,6 +2120,9 @@ output_function (struct cgraph_node *node)
      debug info.  */
   if (gimple_has_body_p (function))
     {
+      /* Fixup loops if required to match discovery done in the reader.  */
+      loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
+
       streamer_write_uhwi (ob, 1);
       output_struct_function_base (ob, fn);
 
@@ -2177,6 +2180,7 @@ output_function (struct cgraph_node *node)
 
       output_cfg (ob, fn);
 
+      loop_optimizer_finalize ();
       pop_cfun ();
    }
   else
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/pr85422.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr85422.c
new file mode 100644
index 0000000..bcc551d
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr85422.c
@@ -0,0 +1,13 @@
+/* { dg-do link } */
+
+int
+main (void)
+{
+  #pragma acc parallel
+  #pragma acc loop
+  for (int i = 1; i < 10; i++)
+    for (;;)
+      ;
+
+  return 0;
+}