eliminating mpc/mpfr and reducing gmp

Richard Guenther richard.guenther@gmail.com
Mon Sep 27 20:59:00 GMT 2010


On Mon, Sep 27, 2010 at 1:39 PM, Jay K <jay.krell@cornell.edu> wrote:
>
> Wow that is fast.
>
>
> My fastest machine, and I have several slower:
>
>
> gmp
> time sh -c "CC=gcc-4.2 ./configure none-none-none -disable-shared -enable-static && make && ssh root@localhost \"cd `pwd` && make install\""
> real    2m2.594s
>
> mpfr
> time sh -c "./configure -disable-shared -enable-static && make && ssh root@localhost \"cd `pwd` && make install\""
> real    0m43.756s
>
> mpc
> time sh -c "./configure -disable-shared -enable-static && make && ssh root@localhost \"cd `pwd` && make install\""
> real    0m15.495s
>
>
> which is still a significant fraction of building cc1 (I don't have that time sorry)
>
> I used to use Cygwin. Things add up much faster there.
>
>
>> mpfr et al. If you're not, it only happens once.
>
>
> Almost anything long but incremental can be justified via incrementality.
> But there is also, occasionally, mass bouts of trying to get the configure switches just right and
> starting over repeatedly...at least me being unsure of incrementality in the fact of rerunning configure...
>
>
> Anyway, just putting it out there, probably won't happen, but  configure -without-mpc -without-mpfr might be nice
> and aren't difficult, -without-gmp much better, but I can't yet claim it isn't difficult.
> Maybe, something like, if gmp is "in tree", after configure, the Makefile could be hacked down
> to omit mpf, mpq, and lots others, but then the linkage between gcc and gmp gets messy.
>   i.e. as gmp changes.

No, we don't want that.  It'll exlode the testing matrix and we'd get
weird bugreports for missed optimizations.

Richard.

>
>  - Jay
>
> ----------------------------------------
>> Date: Mon, 27 Sep 2010 11:37:04 +0100
>> From: aph@redhat.com
>> To: jay.krell@cornell.edu
>> CC: gcc@gcc.gnu.org
>> Subject: Re: eliminating mpc/mpfr and reducing gmp
>>
>> On 09/27/2010 01:23 AM, Jay K wrote:
>> >
>> > Hi. You know, gmp/mpfr/mpc are a significant
>> > portion of building any frontend/backend.
>>
>> I disagree. Most of the time I don't notice them.
>>
>> > The result is a lot faster to build, if you are just doing a just
>> > a single stage build of a compiler.
>>
>> Sure, but if you're working on the compiler you don't need to rebuild
>> mpfr et al. If you're not, it only happens once.
>>
>> On my box, for mpc:
>>
>> real 0m2.624s
>> user 0m3.336s
>> sys 0m1.663s
>>
>> and for mpfr:
>>
>> real 0m4.484s
>> user 0m12.006s
>> sys 0m5.127s
>>
>> Andrew.
>
>



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