https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88509
--- Comment #3 from Rafael Avila de Espindola <rafael at espindo dot la> ---
(In reply to Jakub Jelinek from comment #2)
> I must say I don't understand your suggestion. bar is not a pointer and its
> address is non-NULL no matter whether it has been already initialized or not.
> What kind of assembly you'd like to see for f?
Bar is not a pointer, but a guard variable for bar can be. It is initially null
and is set to bar's address once bar is initialized.
I think the assembly for f could be:
_Z1fv:
movq %fs:__guard_for_bar@tpoff, %rax
testq %rax, %rax
je .L15
ret
.L15:
pushq %rbx
movq %fs:0, %rbx
leaq _ZL3bar@tpoff(%rbx), %rdi
call _ZN3fooC1Ev
leaq _ZL3bar@tpoff(%rbx), %rax
movq %rax, %fs:__guard_for_bar@tpoff
popq %rbx
ret
The .L15 label could even be moved to a cold section.
