[committed] Fix ICE in cleanup_omp_return (PR c++/42234)

[Jakub Jelinek]

Hi!

The attached testcase ICEd on the 4.4 branch because the block preceeding
GIMPLE_OMP_RETURN was empty and thus last_stmt returned NULL.
While 4.5 doesn't ICE on this testcase, it has the same problem latently.

Bootstrapped/regtested on x86_64-linux, committed to trunk/4.4.

2009-12-01  Jakub Jelinek  <jakub@redhat.com>

	PR c++/42234
	* tree-cfgcleanup.c (cleanup_omp_return): Don't ICE if control_bb
	contains no statements.

	* g++.dg/gomp/pr42234.C: New test.

--- gcc/tree-cfgcleanup.c.jj	2009-04-24 21:41:34.000000000 +0200
+++ gcc/tree-cfgcleanup.c	2009-12-01 14:46:43.000000000 +0100
@@ -1,5 +1,5 @@
 /* CFG cleanup for trees.
-   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -517,7 +517,7 @@ cleanup_omp_return (basic_block bb)
   control_bb = single_pred (bb);
   stmt = last_stmt (control_bb);
 
-  if (gimple_code (stmt) != GIMPLE_OMP_SECTIONS_SWITCH)
+  if (stmt == NULL || gimple_code (stmt) != GIMPLE_OMP_SECTIONS_SWITCH)
     return false;
 
   /* The block with the control statement normally has two entry edges -- one
--- gcc/testsuite/g++.dg/gomp/pr42234.C.jj	2009-12-01 14:49:26.000000000 +0100
+++ gcc/testsuite/g++.dg/gomp/pr42234.C	2009-12-01 14:49:10.000000000 +0100
@@ -0,0 +1,19 @@
+// PR c++/42234
+// { dg-do compile }
+// { dg-options "-fopenmp" }
+
+extern int foo (void);
+
+void
+bar (int x)
+{
+  #pragma omp critical
+    {
+      int j;
+      for (j = 0; j < foo (); j++)
+	;
+      if (0)
+        if (x >= 4)
+	  ;
+    }
+}

	Jakub