[Bug target/105576] x86: Support a machine constraint to get raw symbol name

[i at maskray dot me via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105576

--- Comment #6 from Fangrui Song <i at maskray dot me> ---
(In reply to Hongtao.liu from comment #4)
> constraint "i" + "%p0"?
> 
>   asm (".pushsection .xxx,\"aw\"; .dc.a %p0; .popsection" :: "i"(addr)); //
> supported on aarch64 and riscv
>   asm (".pushsection .xxx,\"aw\"; .dc.a %p0; .popsection" :: "i"(&var)); //
> supported on aarch64

It looks like %p0 + "i" doesn't work with -fpie or -fpic...

void k();
void foo() {
  asm("call %p0" :: "i"(k));
}