re PR tree-optimization/50682 (ICE: SIGSEGV in main_block_label with -O2…

re PR tree-optimization/50682 (ICE: SIGSEGV in main_block_label with -O2 -fnon-call-exceptions -ftracer)

	PR tree-optimization/50682
	* tree-eh.c (maybe_remove_unreachable_handlers): New function.
	* tree-flow.h (maybe_remove_unreachable_handlers): New prototype.
	* tree-optimize.c (execute_cleanup_cfg_post_optimizing): Call it.

	* g++.dg/opt/pr50682.C: New test.

From-SVN: r181785

gcc/ChangeLog

+2011-11-28  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/50682
+	* tree-eh.c (maybe_remove_unreachable_handlers): New function.
+	* tree-flow.h (maybe_remove_unreachable_handlers): New prototype.
+	* tree-optimize.c (execute_cleanup_cfg_post_optimizing): Call it.
+
 2011-11-28  Georg-Johann Lay  <avr@gjlay.de>
 
 	* doc/extend.texi (AVR Built-in Functions): Add documentation for

gcc/testsuite/ChangeLog

+2011-11-28  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/50682
+	* g++.dg/opt/pr50682.C: New test.
+
 2011-11-28  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/51308

gcc/testsuite/g++.dg/opt/pr50682.C

+// PR tree-optimization/50682
+// { dg-do compile }
+// { dg-options "-O2 -fnon-call-exceptions -ftracer -fno-tree-ccp -fno-tree-copy-prop -fno-tree-dce" }
+
+void foo () __attribute__ ((__noreturn__));
+int baz ();
+
+const int &
+bar (const int &x, const int &y)
+{
+  if (x >= y)
+    return y;
+  return x;
+}
+
+int a, b;
+
+struct S
+{
+  ~S ();
+  bool m ()
+  {
+    int l = bar (a, b);
+    int r = baz ();
+    if (r)
+        r = l;
+      return r;
+  }
+};
+
+void
+test ()
+{
+  S s;
+  if (!s.m ())
+    foo ();
+  if (!s.m ())
+    foo ();
+}

gcc/tree-eh.c

@@ -3473,6 +3473,29 @@ remove_unreachable_handlers (void)
 #endif
 }
 
+/* Remove unreachable handlers if any landing pads have been removed after
+   last ehcleanup pass (due to gimple_purge_dead_eh_edges).  */
+
+void
+maybe_remove_unreachable_handlers (void)
+{
+  eh_landing_pad lp;
+  int i;
+
+  if (cfun->eh == NULL)
+    return;
+              
+  for (i = 1; VEC_iterate (eh_landing_pad, cfun->eh->lp_array, i, lp); ++i)
+    if (lp && lp->post_landing_pad)
+      {
+	if (label_to_block (lp->post_landing_pad) == NULL)
+	  {
+	    remove_unreachable_handlers ();
+	    return;
+	  }
+      }
+}
+
 /* Remove regions that do not have landing pads.  This assumes
    that remove_unreachable_handlers has already been run, and
    that we've just manipulated the landing pads since then.  */

gcc/tree-flow.h

@@ -789,6 +789,7 @@ extern bool maybe_duplicate_eh_stmt_fn (struct function *, gimple,
 extern bool maybe_duplicate_eh_stmt (gimple, gimple);
 extern bool verify_eh_edges (gimple);
 extern bool verify_eh_dispatch_edge (gimple);
+extern void maybe_remove_unreachable_handlers (void);
 
 /* In tree-ssa-pre.c  */
 struct pre_expr_d;

gcc/tree-optimize.c

@@ -159,6 +159,7 @@ static unsigned int
 execute_cleanup_cfg_post_optimizing (void)
 {
   cleanup_tree_cfg ();
+  maybe_remove_unreachable_handlers ();
   cleanup_dead_labels ();
   group_case_labels ();
   if ((flag_compare_debug_opt || flag_compare_debug)