Don't crash on constant right shift.

From-SVN: r170307

diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index ebe4f282f8f1e8ecb0823dc6fb178a423e1728b6..a073f9dfae9c9d8852e5e6dcf39cda7da57e8e43 100644 (file)
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -5859,13 +5859,21 @@ Binary_expression::do_get_tree(Translate_context* context)
   tree eval_saved = NULL_TREE;
   if (is_shift_op)
     {
-      if (!DECL_P(left))
-       left = save_expr(left);
-      if (!DECL_P(right))
-       right = save_expr(right);
       // Make sure the values are evaluated.
-      eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
-                                  void_type_node, left, right);
+      if (!DECL_P(left) && TREE_SIDE_EFFECTS(left))
+       {
+         left = save_expr(left);
+         eval_saved = left;
+       }
+      if (!DECL_P(right) && TREE_SIDE_EFFECTS(right))
+       {
+         right = save_expr(right);
+         if (eval_saved == NULL_TREE)
+           eval_saved = right;
+         else
+           eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
+                                        void_type_node, eval_saved, right);
+       }
     }
 
   tree ret = fold_build2_loc(this->location(),
@@ -5914,8 +5922,9 @@ Binary_expression::do_get_tree(Translate_context* context)
       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
                            compare, ret, overflow_result);
 
-      ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
-                           TREE_TYPE(ret), eval_saved, ret);
+      if (eval_saved != NULL_TREE)
+       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
+                             TREE_TYPE(ret), eval_saved, ret);
     }
 
   return ret;