middle-end/93273 - fix sinking clobbers across backedges

The previous work to fix PR93199 didn't take into account backedges
when defering insertion.  The following simply avoids to defer in that
case since we know we'll not take secondary opportunities there.

2020-01-15  Richard Biener  <rguenther@suse.de>

        PR middle-end/93273
        * tree-eh.c (sink_clobbers): If we already visited the destination
        block do not defer insertion.
        (pass_lower_eh_dispatch::execute): Maintain BB_VISITED for
        the purpose of defered insertion.

	* g++.dg/torture/pr93273.C: New testcase.

gcc/ChangeLog

+2020-01-15  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/93273
+	* tree-eh.c (sink_clobbers): If we already visited the destination
+	block do not defer insertion.
+	(pass_lower_eh_dispatch::execute): Maintain BB_VISITED for
+	the purpose of defered insertion.
+
 2020-01-15  Jakub Jelinek  <jakub@redhat.com>
 
 	* BASE-VER: Bump to 10.0.1.

gcc/testsuite/ChangeLog

+2020-01-15  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/93273
+	* g++.dg/torture/pr93273.C: New testcase.
+
 2020-01-15  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR tree-optimization/93247

gcc/testsuite/g++.dg/torture/pr93273.C

+// { dg-do compile }
+
+void _setjmp(void *);
+struct S { ~S(); };
+void * (* fn)();
+void f();
+void g()
+{
+  S s;
+  _setjmp(fn());
+  []{ f(); }();
+}

gcc/tree-eh.c

@@ -3622,7 +3622,7 @@ sink_clobbers (basic_block bb,
 
   gimple *first_sunk = NULL;
   gimple *last_sunk = NULL;
-  if (sunk)
+  if (sunk && !(succbb->flags & BB_VISITED))
     dgsi = gsi_start (sunk[succbb->index]);
   else
     dgsi = gsi_after_labels (succbb);
@@ -3910,6 +3910,7 @@ pass_lower_eh_dispatch::execute (function *fun)
 	  else if (!any_resx_to_process)
 	    sink_clobbers (bb, NULL, &any_resx_to_process);
 	}
+      bb->flags &= ~BB_VISITED;
     }
   if (redirected)
     {
@@ -3940,6 +3941,7 @@ pass_lower_eh_dispatch::execute (function *fun)
 	      gsi_insert_seq_before (&gsi, sunk[bb->index], GSI_NEW_STMT);
 	      sunk[bb->index] = NULL;
 	    }
+	  bb->flags |= BB_VISITED;
 	}
       free (rpo);
       free (sunk);