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



On Wed, Jun 17, 2009 at 9:01 PM, Jakub Jelinek<jakub redhat com> wrote:
> On Wed, Jun 17, 2009 at 08:56:58PM +0200, drago01 wrote:
>> > 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?
>
> Of course it is.  You trash caches by rarely used functions.  You don't want
> to optimize rarely used code at the expense of code size, only the often used.

OK, fair enough.


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