[Bug tree-optimization/56099] Empty static noinline functions aren't called from optimized code

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56099

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> 2013-01-24 19:22:43 UTC ---
(In reply to comment #4)
> You are saying I also need to place some __asm__ into this noinline function?
> Doesn't this look like working around some bugs in gcc? User doesn't need to
> know how gcc is doing this inside, weather it is cloning something or treats it
> as pure or not. noinline means do-not-inline, no matter what is inside.


No it is not working around a bug in GCC.  You wrote the function with no side
effects so GCC decided to remove the call to the function as it has no side
effects.  The inline-asm causes GCC to see there are side effects in the
function which are unknown to GCC and does nothing to it.

> 
> I originally asked for a simple basic thing, and so many gcc guts got exposed
> by this.