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

        optimizing computed gotos.

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



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@123067 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 12 insertions, 1 deletions

diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 202a69e2c8f..fa4800e00c2 100644
--- a/gcc/tree-cfg.c
+++ b/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 ();
 }