https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114968
--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
What is the reason behind
/* mingw32 atexit function is safe to use in shared libraries. Use it
to register C++ static destructors. */
#define TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT hook_bool_void_true
?
Couldn't we just drop that?
I mean, when using atexit, GCC needs to emit wrapper functions around the
destructors,
like
__tcf_0:
pushq %rbp
.seh_pushreg %rbp
movq %rsp, %rbp
.seh_setframe %rbp, 0
subq $32, %rsp
.seh_stackalloc 32
.seh_endprologue
leaq _ZZ3foovE1s(%rip), %rax
movq %rax, %rcx
call _ZN1SD1Ev
nop
addq $32, %rsp
popq %rbp
ret
while with __cxa_atexit one can just pass the destructor itself to the
__cxa_atexit function (indeed with slightly more instructions there because in
addition to the function pointer it needs to pass the address of the object and
__dso_handle).
But it is still smaller.
Anyway, if there is some strong reason to keep it, I think it would be better
to avoid adding yet another GTY tree, the __cxa_throw last argument type is the
same as __cxa_atexit/__cxa_thread_atexit.
