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Re: Changing the default 32-bit x86 arch for Fedora 12 (#2)



On Wed, Jun 17, 2009 at 8:46 PM, Jakub Jelinek<jakub redhat com> wrote:
> On Wed, Jun 17, 2009 at 02:41:54PM -0400, Bill Nottingham wrote:
>> Gregory Maxwell (gmaxwell gmail com) said:
>> > Consider:
>> >
>> > -Os on the x86 build?
>>
>> Back when I tested before, -Os unilaterally made things worse across
>> Athlon64/C2D/Atom.
>
> Note that GCC 4.4 switches -Os on for unlikely executed basic blocks and/or
> unlikely executed functions (of course profile feedback helps here a lot,
> but even without it the heuristics gets it right in many cases), so forcing
> -Os for all code, even hot, is not a good idea.
> On the other side, compiling everything with -O3 is going to bloat code a
> lot, just compile with -O3 the hot compilation units or even better just
> hot functions.

Is this (bloated code) really a problem if the code runs faster?


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