re PR tree-optimization/30984 (ICE with computed goto and constants)

        * tree-cfg.c (find_taken_edge): Tighten conditions for
        optimizing computed gotos.

        * PR tree-optimization/30984
        * gcc.c-torture/pr30984.c: New test.

From-SVN: r123067

gcc/ChangeLog

+2007-03-19  Jeff Law  <law@redhat.com>
+
+	* tree-cfg.c (find_taken_edge): Tighten conditions for
+	optimizing computed gotos.
+
 2007-03-19  Michael Matz  <matz@suse.de>
 
 	* builtins.c (expand_builtin_sync_operation,

gcc/testsuite/ChangeLog

+2007-03-19  Jeff Law  <law@redhat.com>
+
+	* PR tree-optimization/30984
+	* gcc.c-torture/pr30984.c: New test.
+
 2007-03-19  Andrew Pinski  <andrew_pinski@playstation.sony.com>
 	Richard Guenther  <rguenther@suse.de>
 

gcc/testsuite/gcc.c-torture/compile/pr30984.c

+int fs_exec(int ino)
+{
+ void *src = 0;
+ if (ino)
+   src = (void*)0xe000;
+ goto *src;
+}

gcc/tree-cfg.c

@@ -2039,7 +2039,18 @@ find_taken_edge (basic_block bb, tree val)
     return find_taken_edge_switch_expr (bb, val);
 
   if (computed_goto_p (stmt))
-    return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
+    {
+      /* Only optimize if the argument is a label, if the argument is
+	 not a label then we can not construct a proper CFG.
+
+         It may be the case that we only need to allow the LABEL_REF to
+         appear inside an ADDR_EXPR, but we also allow the LABEL_REF to
+         appear inside a LABEL_EXPR just to be safe.  */
+      if ((TREE_CODE (val) == ADDR_EXPR || TREE_CODE (val) == LABEL_EXPR)
+	  && TREE_CODE (TREE_OPERAND (val, 0)) == LABEL_DECL)
+	return find_taken_edge_computed_goto (bb, TREE_OPERAND (val, 0));
+      return NULL;
+    }
 
   gcc_unreachable ();
 }