On Sat, Oct 7, 2023 at 3:08 PM Hanke Zhang via Gcc <gcc@gcc.gnu.org> wrote:
>
> Hi, I've recently been working on static local variables in C. I would
> like to ask about some questions about that.
>
> For example, for the following program,
>
> void foo() {
> static int x = 0;
> x++;
> }
>
> int main() {
> foo();
> }
>
> After optimization with the -O3 -flto option, the entire program will
> look something like this:
>
> int main() {
> x_foo++;
> }
>
> The question I want to ask is, why not optimize the 'x_foo++' line of
> code out? Because its scope will only be in foo, and it will not be
> read at all for the entire program. Is it because it is stored in the
> global data area? Or are there other security issues?
I think there's bugreports tracking our weak ability to remove
TU local not escaping globals that are both written and read
(we can handle write-only and const fine).
Richard.
>
> Thanks
> Hanke Zhang
