17 Regression: over optimization at -O2

[NewSigma]

godbolt: https://godbolt.org/z/4xEEz6fsY

#include <iostream>
#include <coroutine>
#include <utility>
#include <vector>

struct Promise {
    std::vector<int> obj;

    ~Promise() {
        std::cout << "~Promise: " << obj.data() << std::endl;
    }

    auto get_return_object() { return std::coroutine_handle<Promise>::from_promise(*this); };
    std::suspend_never initial_suspend() noexcept { return {}; }
    std::suspend_never final_suspend() noexcept { return {}; }
    std::suspend_always yield_value(std::vector<int> b) noexcept {
        obj = std::move(b);
        return {};
    }
    void return_void() noexcept {}
    void unhandled_exception() {}
};

struct coro {
    using promise_type = Promise;

    std::vector<int> arr;
    std::coroutine_handle<Promise> handle;

    coro(std::coroutine_handle<Promise> handle_) noexcept {
        handle = handle_;
        arr = std::move(handle_.promise().obj);
    }
};

coro fn() {
    co_yield std::vector<int>(1);
}

int main(int argc, char** argv) {
    coro cr = fn();
    std::cout << "main: " << cr.arr.data() << std::endl;
    cr.handle.resume();
    return 0;
}

The code works fine using clang 16, but it breaks using 17 ~ trunk.

Possible wrong result(-O2):
main: 0x61c7ada362f0
~Promise: 0x61c7ada362f0

Expected result(-O0):
main: 0x61c7ada362f0
~Promise: 0

[llvmbot]

@llvm/issue-subscribers-coroutines

Author: None (NewSigma)

godbolt: https://godbolt.org/z/4xEEz6fsY

#include <iostream>
#include <coroutine>
#include <utility>
#include <vector>

struct Promise {
    std::vector<int> obj;

    ~Promise() {
        std::cout << "~Promise: " << obj.data() << std::endl;
    }

    auto get_return_object() { return std::coroutine_handle<Promise>::from_promise(*this); };
    std::suspend_never initial_suspend() noexcept { return {}; }
    std::suspend_never final_suspend() noexcept { return {}; }
    std::suspend_always yield_value(std::vector<int> b) noexcept {
        obj = std::move(b);
        return {};
    }
    void return_void() noexcept {}
    void unhandled_exception() {}
};

struct coro {
    using promise_type = Promise;

    std::vector<int> arr;
    std::coroutine_handle<Promise> handle;

    coro(std::coroutine_handle<Promise> handle_) noexcept {
        handle = handle_;
        arr = std::move(handle_.promise().obj);
    }
};

coro fn() {
    co_yield std::vector<int>(1);
}

int main(int argc, char** argv) {
    coro cr = fn();
    std::cout << "main: " << cr.arr.data() << std::endl;
    cr.handle.resume();
    return 0;
}

The code works fine using clang 16, but it breaks using 17 ~ trunk.

Possible wrong result(-O2):
main: 0x61c7ada362f0
~Promise: 0x61c7ada362f0

Expected result(-O0):
main: 0x61c7ada362f0
~Promise: 0

[DimitryAndric]

Only occurs at -O2:

$ valgrind ./pr123347
==781807== Memcheck, a memory error detector
==781807== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==781807== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==781807== Command: ./pr123347
==781807==
main: 0x4e380f0
~Promise: 0x4e380f0
==781807== Invalid free() / delete / delete[] / realloc()
==781807==    at 0x484A61D: operator delete(void*, unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==781807==    by 0x109365: deallocate (new_allocator.h:172)
==781807==    by 0x109365: deallocate (allocator.h:208)
==781807==    by 0x109365: deallocate (alloc_traits.h:513)
==781807==    by 0x109365: _M_deallocate (stl_vector.h:389)
==781807==    by 0x109365: ~_Vector_base (stl_vector.h:368)
==781807==    by 0x109365: ~vector (stl_vector.h:738)
==781807==    by 0x109365: ~coro (???:24)
==781807==    by 0x109365: main (???:45)
==781807==  Address 0x4e380f0 is 0 bytes inside a block of size 4 free'd
==781807==    at 0x484A61D: operator delete(void*, unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==781807==    by 0x1093AC: fn() [clone .resume] (pr123347.cpp:36)
==781807==    by 0x109350: resume (coroutine:242)
==781807==    by 0x109350: main (???:43)
==781807==  Block was alloc'd at
==781807==    at 0x4846FA3: operator new(unsigned long) (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==781807==    by 0x109236: allocate (new_allocator.h:151)
==781807==    by 0x109236: allocate (allocator.h:196)
==781807==    by 0x109236: allocate (alloc_traits.h:478)
==781807==    by 0x109236: _M_allocate (stl_vector.h:380)
==781807==    by 0x109236: _M_create_storage (stl_vector.h:398)
==781807==    by 0x109236: _Vector_base (stl_vector.h:334)
==781807==    by 0x109236: vector (stl_vector.h:557)
==781807==    by 0x109236: fn() (???:37)
==781807==    by 0x1092D0: main (pr123347.cpp:41)

Looks like gcc doesn't have this issue.