cvs commit: src/sys/kern kern_sig.c

[David O'Brien]

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.
    ..snip..

The -O2 options that affect size are:
    -falign-functions  -falign-jumps  -falign-loops -falign-labels
    -freorder-blocks -fprefetch-loop-arrays