On Tue, May 7, 2019 at 4:43 PM Jason Merrill <ja...@redhat.com> wrote:
>
> * typeck.c (build_static_cast_1): Use cp_build_addr_expr.
>
> For GCC 9 I fixed this bug with a patch to gimplify_cond_expr, but this
> function was also doing the wrong thing.
>
> Using build_address does not push the ADDR_EXPR down into the arms of a
> COND_EXPR, which we need for proper handling of conversion of an lvalue ?:
> to another reference type.
Yet another tweak that would have fixed this bug: we should treat INIT_EXPR
and MODIFY_EXPR differently for determining whether this is a simple empty
class copy, since a TARGET_EXPR on the RHS is direct initialization if
INIT_EXPR but copy if MODIFY_EXPR.
* cp-gimplify.c (simple_empty_class_p): Also true for MODIFY_EXPR.
commit 4ee9e054cba31bd532061bd357477e757b5b284a
Author: Jason Merrill <ja...@redhat.com>
Date: Sat Mar 2 01:07:41 2019 -0500
PR c++/86485 - simple_empty_class_p
Yet another tweak that would have fixed this bug: we should treat INIT_EXPR
and MODIFY_EXPR differently for determining whether this is a simple empty
class copy, since a TARGET_EXPR on the RHS is direct initialization if
INIT_EXPR but copy if MODIFY_EXPR.
* cp-gimplify.c (simple_empty_class_p): Also true for MODIFY_EXPR.
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index e8c22c071c2..30937b1a1a3 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -594,19 +594,20 @@ gimplify_must_not_throw_expr (tree *expr_p, gimple_seq
*pre_p)
return slot optimization alone because it isn't a copy. */
static bool
-simple_empty_class_p (tree type, tree op)
+simple_empty_class_p (tree type, tree op, tree_code code)
{
+ if (TREE_CODE (op) == COMPOUND_EXPR)
+ return simple_empty_class_p (type, TREE_OPERAND (op, 1), code);
return
- ((TREE_CODE (op) == COMPOUND_EXPR
- && simple_empty_class_p (type, TREE_OPERAND (op, 1)))
- || TREE_CODE (op) == EMPTY_CLASS_EXPR
+ (TREE_CODE (op) == EMPTY_CLASS_EXPR
+ || code == MODIFY_EXPR
|| is_gimple_lvalue (op)
|| INDIRECT_REF_P (op)
|| (TREE_CODE (op) == CONSTRUCTOR
- && CONSTRUCTOR_NELTS (op) == 0
- && !TREE_CLOBBER_P (op))
+ && CONSTRUCTOR_NELTS (op) == 0)
|| (TREE_CODE (op) == CALL_EXPR
&& !CALL_EXPR_RETURN_SLOT_OPT (op)))
+ && !TREE_CLOBBER_P (op)
&& is_really_empty_class (type, /*ignore_vptr*/true);
}
@@ -715,7 +716,7 @@ cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p)
TREE_OPERAND (*expr_p, 1) = build1 (VIEW_CONVERT_EXPR,
TREE_TYPE (op0), op1);
- else if (simple_empty_class_p (TREE_TYPE (op0), op1))
+ else if (simple_empty_class_p (TREE_TYPE (op0), op1, code))
{
/* Remove any copies of empty classes. Also drop volatile
variables on the RHS to avoid infinite recursion from
