This is the mail archive of the
mailing list for the glibc project.
Re: [PATCH 1/3] New make target gen-libm-inputs
- From: Siddhesh Poyarekar <sid at reserved-bit dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: libc-alpha at sourceware dot org
- Date: Mon, 14 Dec 2015 10:19:42 +0530
- Subject: Re: [PATCH 1/3] New make target gen-libm-inputs
- Authentication-results: sourceware.org; auth=none
- References: <20151211101911 dot GA2372 at linaro-laptop dot intra dot reserved-bit dot com> <alpine dot DEB dot 2 dot 10 dot 1512111250360 dot 25021 at digraph dot polyomino dot org dot uk>
On Fri, Dec 11, 2015 at 01:00:25PM +0000, Joseph Myers wrote:
> I don't think adding thousands of tests like that is a good idea (unless
> function implementations genuinely have thousands of branches). Rather,
> you should identify a minimal set of test inputs that actually improve
> branch coverage or increase observed ulps, and only add those inputs to
OK, then that will have to be a completely different workflow. What
do you think about this: add systemtap probes to each branch point in
the libm code and then have a driver link against this libc and
identify an input for each branch. These probe points get built in
only for the gen-libm-inputs target and should get invalidated on the
The downside I see is that the code is slightly harder to read due to
all of these probe points, but it shouldn't be that bad.
> I'm also wary of a makefile rule like this because it's likely that MPFR
> or MPC versions newer than the system ones are required (for example, as
> soon as MPC 1.1 comes out with the performance improvements for mpc_sin
> that went in two years ago but still haven't appeared in a release, I
> intend to move the remaining csin tests to auto-libm-test-in, which will
> mean regeneration may take over 10 minutes when using older MPC versions).
That is why this rule is optional, i.e. at the descretion of
developers only. That said, I could add a configure option to specify
which MPC and MPFR you want to build against. Would that be
> I think that size of auto-libm-test-out illustrates why adding all the
> benchmark inputs would be excessive.
Fair enough; it worked for me because I found bugs, but I see what you
> > +# Very simple target. We don't really care for any glibc configuration to
> > +# affect this. TODO: add configure check to determine if MPC, MPFR development
> > +# libraries are available.
> > +$(objpfx)gen-auto-libm-tests: $(gen-auto-libm-tests-modules:%=%.c)
> > + $(CC) -o $@ $^ -O2 -std=gnu11 -Wall -Wextra -lmpc -lmpfr -lgmp
> Of course this should be BUILD_CC.
> > FUNC_mpfr_ff_f ("pow", mpfr_pow, false),
> > + FUNC_mpfr_f_f ("rint", mpfr_erf, false),
> > FUNC_mpfr_f_f ("sin", mpfr_sin, false),
> > FUNC ("sincos", ARGS1 (type_fp), RET2 (type_fp, type_fp), false, false,
> > false, CALC (mpfr_f_11, mpfr_sin_cos)),
> No. If you want to test extra functions, add the support required to do
> so properly, not hacking things up to accept test inputs whose outputs are
> both meaningless and unused.
Sorry, I don't even remember how I came up with that bit.