From: Qian Cai <c...@lca.pw>
Date: Fri, 12 Jul 2019 20:27:09 -0400
> Actually, GCC would consider it a const with -O2 optimized level because it
> found that it was never modified and it does not understand it is a module
> parameter. Considering the following code.
>
> # cat const.c
> #include <stdio.h>
>
> static int a = 1;
>
> int main(void)
> {
> if (__builtin_constant_p(a))
> printf("a is a const.\n");
>
> return 0;
> }
>
> # gcc -O2 const.c -o const
That's not a complete test case, and with a proper test case that
shows the externalization of the address of &a done by the module
parameter macros, gcc should not make this optimization or we should
define the module parameter macros in a way that makes this properly
clear to the compiler.
It makes no sense to hack around this locally in drivers and other
modules.
Thank you.
