On Tue, 24 Apr 2018, Michael Matz wrote:
> Sure but even for that we need to decide if we want to go that or the
> opposite way, and that's not easy when a deadline is lurking behind you.
I am surprised there is any question. Even gcc-3.4 optimizes reg vars over asms,
on a testcase not unlike the very one you've used I see:
register int foo asm("ebx");
void g(void);
void f(void)
{
foo=0;
asm("foo=1");
if (foo) g();
}
.globl f
.type f, @function
f:
.LFB2:
xorl %ebx, %ebx
#APP
foo=1
#NO_APP
ret
(here GCSE makes the propagation)
Besides, I don't really understand the objection about changing the docs for
gcc-8.1. Even if there's a doubt about future development, improving the
documentation to explain the behavior of a released compiler should be good.
Right now the docs are simply wrong.
Alexander
