re PR tree-optimization/33920 (Segfault in combine_blocks/tree-if-conv.c)

        PR tree-optimization/33920
        * tree-if-conv.c (tree_if_conversion): Force predicate of single
        successor bb to true when predecessor bb has NULL predicate.
        (find_phi_replacement_condition): Assert that tmp_cond is non-null.

testsuite/ChangeLog:

        PR tree-optimization/33920
        * gcc.dg/tree-ssa/pr33290.c: New test.

From-SVN: r129696

gcc/ChangeLog

+2007-10-28  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR tree-optimization/33920
+	* tree-if-conv.c (tree_if_conversion): Force predicate of single
+	successor bb to true when predecessor bb has NULL predicate.
+	(find_phi_replacement_condition): Assert that tmp_cond is non-null.
+
 2007-10-28  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	* config/mips/mips.md: Add combiner patterns for DImode extensions

gcc/testsuite/ChangeLog

+2007-10-28  Martin Michlmayr  <tbm@cyrius.com>
+	    Uros Bizjak  <ubizjak@gmail.com>
+
+	PR tree-optimization/33920
+	* gcc.dg/tree-ssa/pr33290.c: New test.
+
 2007-10-27 Jerry DeLisle <jvdelisle@gcc.gnu.org>
 
 	PR fortran/31306

gcc/testsuite/gcc.dg/tree-ssa/pr33920.c

+/* Testcase by Martin Michlmayr <tbm@cyrius.com> */
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+typedef union lispunion *object;
+struct character
+{
+  long e;
+};
+extern struct symbol Cnil_body;
+extern struct symbol Ct_body;
+struct vector
+{
+  object *v_self;
+};
+union lispunion
+{
+  struct vector v;
+};
+void init_code ()
+{
+  object V659;
+  object _x, _y;
+  object V643;
+  long V648;
+  unsigned char V653;
+  object V651;
+  object V654;
+  object V658;
+
+T1240:
+  if (V648 >= (long)V651)
+    goto T1243;
+  V653 = ((char *) V654->v.v_self)[V648];
+  V659 = (object) V654 + V653;
+T1261:
+  V658 =
+    (object)
+     V659 ? (object) & Ct_body : (object) & Cnil_body;
+  if (V658 == (object) & Cnil_body)
+    goto T1249;
+  goto T1224;
+T1249:
+ V648 = (long) V648 + 1;
+  goto T1240;
+T1243:
+  V643 = (object) & Cnil_body;
+T1224:
+  _y = V643;
+  number_plus (_x, _y);
+}

gcc/tree-if-conv.c

@@ -189,8 +189,14 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
       if (single_succ_p (bb))
 	{
 	  basic_block bb_n = single_succ (bb);
-	  if (cond != NULL_TREE)
-	    add_to_predicate_list (bb_n, cond);
+
+	  /* Successor bb inherits predicate of its predecessor. If there
+	     is no predicate in predecessor bb, then consider successor bb
+	     as always executed.  */
+	  if (cond == NULL_TREE)
+	    cond = boolean_true_node;
+
+	  add_to_predicate_list (bb_n, cond);
 	}
     }
 
@@ -724,6 +730,8 @@ find_phi_replacement_condition (struct loop *loop,
 
   /* Select condition that is not TRUTH_NOT_EXPR.  */
   tmp_cond = (first_edge->src)->aux;
+  gcc_assert (tmp_cond);
+
   if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
     {
       edge tmp_edge;