[Bug middle-end/20408] Unnecessary code generated for empty structs

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=20408

--- Comment #22 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Wed May 22 21:39:08 2019
New Revision: 271523

URL: https://gcc.gnu.org/viewcvs?rev=271523&root=gcc&view=rev
Log:
        PR c++/20408 - unnecessary code for empty struct.

Here initializing the argument from a TARGET_EXPR isn't an empty class
copy even though the type is !TREE_ADDRESSABLE, so we should check
simple_empty_class_p.

        * call.c (build_call_a): Use simple_empty_class_p.

Added:
    trunk/gcc/testsuite/g++.dg/tree-ssa/empty-3.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/cp/cp-gimplify.c
    trunk/gcc/cp/cp-tree.h