Messages in this thread | | | Date | Wed, 07 Oct 2009 08:35:09 -0700 | From | Richard Henderson <> | Subject | Re: [PATCH 0/4] jump label patches |
| |
On 10/06/2009 05:14 PM, Roland McGrath wrote: > Kernel builds usually use -Os. Is there anything else we can do now (4.4) > to influence this placement (while keeping the unlikely target block inside > a scope, i.e. macro, with the asm goto)?
I think -Os includes -freorder-blocks as well.
> if (0) yes: maybe = 1;
Anything with "if (0)" in it (even with __builtin_expect) is going to be folded away too early to be useful.
I can't think of any way to manipulate block placement from the source level at this time that doesn't add more code along the fast path, obviating the asm goto.
r~
| |