https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102528
--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
#include <coroutine>
struct simple {
struct promise_type {
void return_void() {}
std::suspend_never initial_suspend() { return {}; }
std::suspend_never final_suspend() noexcept { return {}; }
void unhandled_exception() { /*throw;*/ }
simple get_return_object() { return {}; }
};
std::true_type await_ready() {return {}; }
void await_suspend(std::coroutine_handle<>) {}
void await_resume() {}
};
inline simple
test1() {
co_return;
}
inline simple
test2() {
co_await test1();
co_return;
}
void test() {
test1();
}
is enough to reproduce at -O2
-std=c++20 -O2 -S -fno-reorder-blocks-and-partition -fno-exceptions
-fno-unwind-tables -fno-asynchronous-unwind-tables
^^ makes the output a little less complicated.
.text
.p2align 4
__Z5test1PZ5test1vE15_Z5test1v.Frame.actor:
<SNIP>
jmp __ZdlPv
L3:
ud2
.p2align 4
__Z5test1PZ5test1vE15_Z5test1v.Frame.destroy:
movzwl 32(%rdi), %eax
<SNIP>
ret
.p2align 4,,10
.p2align 3
L19:
jmp __ZdlPv
L16:
ud2
.p2align 4
.globl __Z4testv
__Z4testv:
ret
L21:
nop
.ident "GCC: (GNU) 12.0.0 20211003 (experimental)"
NOTES:
1/ All traces of test2 are correctly elided (so that it seems we need to have
had a use at some earlier point).
2/ at the start of DSE2 we still hold references to the actor and destroyer
functions (the ramp has been inlined, and the ramp function elided).
3/ DSE2 elides the coroutine frame and the references to the two functions, but
it seems that is too late in the pipeline for them to be removed?
