On Thu, May 07, 2020 at 04:45:30PM -0600, Jason A. Donenfeld wrote: > GCC 10 appears to have changed -O2 in order to make compilation time > faster when using -flto, seemingly at the expense of performance, in > particular with regards to how the inliner works. Since -O3 these days > shouldn't have the same set of bugs as 10 years ago, this commit > defaults new kernel compiles to -O3 when using gcc >= 10.
Would be nice to get some GCC person's feedback on this. But in general, I think you're right in that O3 isn't the code-gen disaster it used to be. > Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com> > --- > init/Kconfig | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/init/Kconfig b/init/Kconfig > index 9e22ee8fbd75..fab3f810a68d 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1245,7 +1245,8 @@ config BOOT_CONFIG > > choice > prompt "Compiler optimization level" > - default CC_OPTIMIZE_FOR_PERFORMANCE > + default CC_OPTIMIZE_FOR_PERFORMANCE_O3 if GCC_VERSION >= 100000 > + default CC_OPTIMIZE_FOR_PERFORMANCE if (GCC_VERSION < 100000 || > CC_IS_CLANG) > > config CC_OPTIMIZE_FOR_PERFORMANCE > bool "Optimize for performance (-O2)" > -- > 2.26.2 >
