Messages in this thread |  | | | From | Andi Kleen <> | | Subject | Re: [PATCH] x86: unify x86 Makefile(s) | | Date | Sat, 29 Dec 2007 03:14:23 +0100 |
| |
On Friday 28 December 2007 23:13:24 Adrian Bunk wrote: > On Fri, Dec 28, 2007 at 10:23:41PM +0100, Sam Ravnborg wrote: > >... > > Noteworthy remarks on the unification: > >... > > - -funit-at-a-time should be easy to unify but it looks like we have a bug > > in 32 bit. We only enable -funit-at-a-time for gcc less than 0400 if they > > support it > > No, we _dis_able it on 32bit if a gcc < 4.0 supports it. > > > (and I recall it is a gcc 4.00 feature). [-lt -> -gt] > >... > > unit-at-a-time was introduced in upstream gcc 3.4 and backported to some > popular 3.3 x86_64 branch. > > i386 and x86_64 go in exactly opposite directions regarding when to use > unit-at-a-time, but that was intentional and we should keep it that way.
i386 disabled it because there were claims that it increased stack size too much, but I haven't seen any real evidence for that. That is why I never added it to x86-64. On the other hand it tends to shrink text size considerably.
I think it should be reevaluated and enabled by default on i386 again.
BTW there is a patch pending for gcc 4.3+ that prevents optimizations that increase stack size unduly. Not sure it has been added there yet, but that was the right fix for these problems anyways.
-Andi
|  |