[PATCH] Fix PR80876

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2017-05-30  Richard Biener  <rguent...@suse.de>

        PR middle-end/80876
        * cfgexpand.c (expand_gimple_cond): Fixup preserving loops again.

        * gcc.dg/torture/pr80876.c: New testcase.

Index: gcc/cfgexpand.c
===================================================================
--- gcc/cfgexpand.c     (revision 248482)
+++ gcc/cfgexpand.c     (working copy)
@@ -2504,9 +2504,9 @@ expand_gimple_cond (basic_block bb, gcon
   new_bb->count = false_edge->count;
   new_bb->frequency = EDGE_FREQUENCY (false_edge);
   add_bb_to_loop (new_bb, dest->loop_father);
-  if (bb->loop_father->latch == bb
-      && bb->loop_father->header == dest)
-    bb->loop_father->latch = new_bb;
+  if (dest->loop_father->latch == bb
+      && dest->loop_father->header == dest)
+    dest->loop_father->latch = new_bb;
   new_edge = make_edge (new_bb, dest, 0);
   new_edge->probability = REG_BR_PROB_BASE;
   new_edge->count = new_bb->count;
Index: gcc/testsuite/gcc.dg/torture/pr80876.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr80876.c      (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr80876.c      (working copy)
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+
+int sy;
+
+void
+fo (char o5)
+{
+  char yh = 0;
+
+  if (o5 == 0)
+    return;
+
+  while (o5 != 0)
+    if (0)
+      {
+       while (yh != 0)
+         {
+           o5 = 0;
+           while (o5 < 2)
+             {
+               sy &= yh;
+               if (sy != 0)
+                 {
+km:
+                   sy = yh;
+                 }
+             }
+           ++yh;
+         }
+      }
+    else
+      {
+       o5 = sy;
+       goto km;
+      }
+}
+
+void
+on (void)
+{
+  fo (sy);
+}