Why we optimize by time by default for < -O2 case?
LI Xin
delphij at delphij.net
Mon Oct 8 19:53:58 PDT 2007
Bruce Evans wrote:
> On Mon, 8 Oct 2007, LI Xin wrote:
>
>> I wonder why we want to optimize by time by default and not by space by
>> default for the system compiler, does the reasoning still hold true?
>
> -O means optimize for time if possible.
>
>> The commit log said:
>>
>> Modified files:
>> contrib/gcc toplev.c
>> Log:
>> Clarify revision 1.14:
>> Gcc 3.1's -O0 and -O1 actually optimized alignment for space, but we
>> feel
>> it should optimize alignment for time like Gcc 2.95 used to.
>> Optimization
>> for space should give 1-byte alignment on i386's, but doesn't quite.
>>
>> Revision Changes Path
>> 1.15 +0 -0 src/contrib/gcc/toplev.c
>
> Without this change, -O pessimizes for time.
Does this affect all platforms or is it i386 only, on the latest GCC
version?
Cheers,
--
Xin LI <delphij at delphij.net> http://www.delphij.net/
FreeBSD - The Power to Serve!
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