Date: Wed, 7 Aug 2024 11:41:24 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Paul Zimmermann <Paul.Zimmermann@inria.fr> Cc: hackers@freebsd.org, numerics@freebsd.org Subject: Re: kargl@freebsd.org, sgk@troutmask.apl.washington.edu, vincenzo.innocente@cern.ch, riemannic@gmail.com, johnmather@sidefx.com Message-ID: <ZrMzNB-Dck9eX2o8@kib.kiev.ua> In-Reply-To: <p9u04j7wah8b.fsf@coriandre.loria.fr> References: <p9u0ed713j4u.fsf@coriandre.loria.fr> <ZrI5pocdm0Zbl9pW@kib.kiev.ua> <p9u04j7wah8b.fsf@coriandre.loria.fr>
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On Wed, Aug 07, 2024 at 10:07:32AM +0200, Paul Zimmermann wrote: > Hi Konstantin, > > > Date: Tue, 6 Aug 2024 17:56:38 +0300 > > From: Konstantin Belousov <kostikbel@gmail.com> > > Cc: hackers@freebsd.org, numerics@freebsd.org > > > > On Tue, Aug 06, 2024 at 02:56:01PM +0200, Paul Zimmermann wrote: > > > Hi, > > > > > > we have updated our comparison with FreeBSD 14.1: > > > > > > https://members.loria.fr/PZimmermann/papers/accuracy.pdf > > > > > > Remaining issues in 14.1: > > > > > > * the powl function is not thread-safe > > This is for 80-bit long double, am I right? > > yes > > > And it is because of the global vars passing values between functions? > > > > I tried to hack something in https://reviews.freebsd.org/D46237 > > thanks. I tried to apply your patch on top of openlibm-0.8.3 (after > stripping lib/msun). Part of it failed: > > $ patch -p1 -i /tmp/D46237.diff > patching file ld80/e_powl.c > Hunk #1 FAILED at 23. > Hunk #2 FAILED at 42. > Hunk #3 succeeded at 85 (offset -41 lines). > Hunk #4 succeeded at 100 (offset -41 lines). > Hunk #5 succeeded at 135 (offset -41 lines). > Hunk #6 succeeded at 158 (offset -41 lines). > Hunk #7 succeeded at 189 (offset -41 lines). > > $ cat ld80/e_powl.c.rej > --- ld80/e_powl.c > +++ ld80/e_powl.c > @@ -23,10 +23,10 @@ > * P[0] x^n + P[1] x^(n-1) + ... + P[n] > */ > static inline long double > -__polevll(long double x, long double *PP, int n) > +__polevll(long double x, const long double *PP, int n) > { > long double y; > - long double *P; > + const long double *P; > > P = PP; > y = *P++; > @@ -42,10 +42,10 @@ > * x^n + P[0] x^(n-1) + P[1] x^(n-2) + ... + P[n] > */ > static inline long double > -__p1evll(long double x, long double *PP, int n) > +__p1evll(long double x, const long double *PP, int n) > { > long double y; > - long double *P; > + const long double *P; > > P = PP; > n -= 1; > > Also I git compiler warnings (maybe due to the rejected part): > > ld80/e_powl.c: In function ‘powl’: > ld80/e_powl.c:374:29: warning: passing argument 2 of ‘__polevll’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] > 374 | w = x * ( z * __polevll( x, P, 3 ) / __p1evll( x, Q, 3 ) ); > | ^ Yes, we have some restructuring there, quite recent. Anyway, the main part of the patch is the marking of the statics with thread local. > > Apart from that, various tests I did seem to indicate the multi-thread issue > has gone, thanks! > Thank you for the testing.
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