[Bug c++/109268] New: Guard variable still provided for static constinit variable

[barry.revzin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109268

            Bug ID: 109268
           Summary: Guard variable still provided for static constinit
                    variable
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: barry.revzin at gmail dot com
  Target Milestone: ---

This program: 

struct X {
    constexpr X() { }
    constexpr ~X() { }
};

int main()
{
    static constinit X data;
}

compiled on gcc trunk with -std=c++2b -O3 emits:

X::~X() [base object destructor]:
        ret
main:
        movzx   eax, BYTE PTR guard variable for main::data[rip]
        test    al, al
        je      .L14
        xor     eax, eax
        ret
.L14:
        push    rcx
        mov     edi, OFFSET FLAT:guard variable for main::data
        call    __cxa_guard_acquire
        test    eax, eax
        jne     .L15
.L5:
        xor     eax, eax
        pop     rdx
        ret
.L15:
        mov     edx, OFFSET FLAT:__dso_handle
        mov     esi, OFFSET FLAT:_ZZ4mainE4data
        mov     edi, OFFSET FLAT:_ZN1XD1Ev
        call    __cxa_atexit
        mov     edi, OFFSET FLAT:guard variable for main::data
        call    __cxa_guard_release
        jmp     .L5

But data is constant-initialized (enforced by constinit), so there shouldn't be
a need for a guard variable in this context? clang does not generate one in
this case.