cvs commit: src/sys/kern kern_sig.c
scottl at samsco.org
Mon Mar 7 20:50:04 GMT 2005
David O'Brien wrote:
> On Thu, Mar 03, 2005 at 07:06:24AM -0700, Scott Long wrote:
>>a bit. Also, there is talk about increasing the default kstack size due
>>to all of the extra inlining that the compiler does with the -O2 option
> I'd love more details on the extra inlining people are seeing with -O2.
> (i.e. specifics) -O2 is not supose to do extra function inlining. That
> is suppose to be a -O3 thing.
> From the GCC manual:
> -O3 Optimize yet more.
> -O3 turns on all optimizations specified by -O2 and also turns on the
> -finline-functions, -fweb and -frename-registers options.
> -O2 Optimize even more.
> GCC performs nearly all supported optimizations that do not involve a
> space-speed tradeoff. The compiler does not perform loop unrolling or
> function inlining when you specify -O2. As compared to -O, this
> option increases both compilation time and the performance of the
> generated code.
> The -O2 options that affect size are:
> -falign-functions -falign-jumps -falign-loops -falign-labels
> -freorder-blocks -fprefetch-loop-arrays
Talk to Bill Paul about the massive amount of inlining that is happening
in the ieee80211 ioctl code, and the no_inline directives he had to use
to kludge around it.
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