On Fri, Jan 12, 2018 at 9:41 PM, Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, Jan 12, 2018 at 08:43:21PM +0100, Arnd Bergmann wrote: >> On Fri, Jan 12, 2018 at 5:39 PM, Segher Boessenkool >> We could theoretically work around it by turning that into >> "#if defined(CONFIG_CC_OPTIMIZE_FOR_SIZE) || >> defined(CONFIG_CRYPTO_AES)", but that seems rather ugly. >> >> My earlier patch already tried to be more specific, turning very >> specific optimizations off rather than moving from -O2 to -Os, >> but that turned out to lead to significantly worse performance, >> where -Os improved performance slightly. Is there a way >> to ask powerpc compilers to use mostly -Os but not the >> specific thing that makes it link to _restgpr_31_x? > > There is no such thing, sorry. Would be very hard to implement, and > older compilers will never get it, so it won't help you anyway :-( We use -Os only for gcc-7.1 and higher, where it produces faster code for AES and avoids running into https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356 > Maybe for now just enable it in crtsavres.S always, with a comment? > That -Os workaround is hopefully not going to live long either... It depends on whether or how soon someone comes up with a better fix for PR83356. gcc-8.0.0 is currently not affected by it, so we could limit the workaround (and the hack in crtsavres.S) to gcc-7-only. Arnd
