[PATCH] Don't ICE on empty bbs with no successors in EH opt (PR middle-end/57499)

[Jakub Jelinek]

Hi!

As the testcase shows, invalid use of noreturn attribute (which we diagnose)
can result in in empty bb with no successors.  This patch fixes
cleanup_empty_eh not to ICE on these.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2014-02-04  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/57499
        * tree-eh.c (cleanup_empty_eh): Bail out on totally empty
        bb with no successors.

        * g++.dg/torture/pr57499.C: New test.

--- gcc/tree-eh.c.jj    2014-01-31 22:22:09.000000000 +0100
+++ gcc/tree-eh.c       2014-02-04 12:35:05.611066852 +0100
@@ -4396,8 +4396,11 @@ cleanup_empty_eh (eh_landing_pad lp)
   /* If the block is totally empty, look for more unsplitting cases.  */
   if (gsi_end_p (gsi))
     {
-      /* For the degenerate case of an infinite loop bail out.  */
-      if (infinite_empty_loop_p (e_out))
+      /* For the degenerate case of an infinite loop bail out.
+        If bb has no successors and is totally empty, which can happen e.g.
+        because of incorrect noreturn attribute, bail out too.  */
+      if (e_out == NULL
+         || infinite_empty_loop_p (e_out))
        return ret;
 
       return ret | cleanup_empty_eh_unsplit (bb, e_out, lp);
--- gcc/testsuite/g++.dg/torture/pr57499.C.jj   2014-02-04 12:52:10.241846755 
+0100
+++ gcc/testsuite/g++.dg/torture/pr57499.C      2014-02-04 12:51:51.000000000 
+0100
@@ -0,0 +1,14 @@
+// PR middle-end/57499
+// { dg-do compile }
+
+struct S
+{
+  ~S () __attribute__ ((noreturn)) {} // { dg-warning "function does return" }
+};
+
+void
+foo ()
+{
+  S s;
+  throw 1;
+}

        Jakub