takes care not to introduce additional temporaries.
Returns TRUE iff the expression was successfully pre-evaluated,
- i.e., if INIT is now side-effect free, except for, possible, a
+ i.e., if INIT is now side-effect free, except for, possibly, a
single call to a constructor. */
bool
if (t == error_mark_node || processing_template_decl)
return true;
- if (TREE_CODE (t) == INIT_EXPR
- && TREE_CODE (TREE_OPERAND (t, 1)) != TARGET_EXPR
- && TREE_CODE (TREE_OPERAND (t, 1)) != CONSTRUCTOR
- && TREE_CODE (TREE_OPERAND (t, 1)) != AGGR_INIT_EXPR)
- {
- TREE_OPERAND (t, 1) = stabilize_expr (TREE_OPERAND (t, 1), initp);
- return true;
- }
-
if (TREE_CODE (t) == INIT_EXPR)
t = TREE_OPERAND (t, 1);
if (TREE_CODE (t) == TARGET_EXPR)
t = TARGET_EXPR_INITIAL (t);
- if (TREE_CODE (t) == COMPOUND_EXPR)
- t = expr_last (t);
+
+ /* If the RHS can be stabilized without breaking copy elision, stabilize
+ it. We specifically don't stabilize class prvalues here because that
+ would mean an extra copy, but they might be stabilized below. */
+ if (TREE_CODE (init) == INIT_EXPR
+ && TREE_CODE (t) != CONSTRUCTOR
+ && TREE_CODE (t) != AGGR_INIT_EXPR
+ && (SCALAR_TYPE_P (TREE_TYPE (t))
+ || lvalue_or_rvalue_with_address_p (t)))
+ {
+ TREE_OPERAND (init, 1) = stabilize_expr (t, initp);
+ return true;
+ }
+
+ if (TREE_CODE (t) == COMPOUND_EXPR
+ && TREE_CODE (init) == INIT_EXPR)
+ {
+ tree last = expr_last (t);
+ /* Handle stabilizing the EMPTY_CLASS_EXPR pattern. */
+ if (!TREE_SIDE_EFFECTS (last))
+ {
+ *initp = t;
+ TREE_OPERAND (init, 1) = last;
+ return true;
+ }
+ }
+
if (TREE_CODE (t) == CONSTRUCTOR)
{
/* Aggregate initialization: stabilize each of the field
return good;
}
- /* If the initializer is a COND_EXPR, we can't preevaluate
- anything. */
- if (TREE_CODE (t) == COND_EXPR)
- return false;
-
if (TREE_CODE (t) == CALL_EXPR)
{
stabilize_call (t, initp);