Re: [PATCH] Add cacos benchmark inputs

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Fri, 4 Oct 2013, Siddhesh Poyarekar wrote:

> On 4 October 2013 20:43, Joseph S. Myers <joseph@codesourcery.com> wrote:
> > On Fri, 4 Oct 2013, Siddhesh Poyarekar wrote:
> >
> >> This patch adds inputs in libm-test.inc as benchmark inputs for cacos.
> >> This needs the recently posted changes to the benchmark framework.  OK
> >> to commit?
> >
> > I don't believe these special cases reflect ordinary input to cacos.
> 
> Agreed, they don't.  I'm using them as a starting point to get the
> function in.  Please let me know if that is not acceptable, since I
> will then not waste time trying to sync up the inputs across the test
> suite and the benchmark suite.

I think it's a mistake to do any sort of syncing of inputs that requires 
manual copying of data from one place to another.  That is, if you want to 
use libm-test.inc for benchmark inputs (bearing in mind that they are 
unrepresentative - so if you did some form of randomized benchmarking to 
get an overall score, rather than doing many runs with one input, then 
many with another inputs, with consequent branch prediction implications, 
then the unrepresentative inputs would need down-weighting, and probably 
more representative inputs would need adding), then libm-test.inc, or a 
source file generating libm-test.inc, needs to be the sole source of that 
data to avoid copies getting out of sync.  In the absence of 
MPFR/MPC-based test generation as discussed at 
<https://sourceware.org/ml/libc-alpha/2013-05/msg00059.html>, that means 
benchmarks would need actually to include libm-test.c (generated in the 
build tree from libm-test.inc), with appropriate predefines as in files 
such as test-double.c to control the type being tested, and work from the 
data tables therein.

-- 
Joseph S. Myers
joseph@codesourcery.com