Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Vincent Lefevre
On 2018-11-19 15:26:00 +0100, Richard Biener wrote: > On Mon, 19 Nov 2018, Vincent Lefevre wrote: > > AFAIK, GCC already changes the exponent range to the binary64 one > > (the lack of subnormals is not an issue, because in case of underflow, > > GCC ignores the computations done with MPFR). > >

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Dennis Clarke
On 11/19/18 5:40 AM, Torbjörn Granlund wrote: Richard Biener writes: > __real x = 3.09126495087690770626068115234375e+8; > __imag x = -4.045689747817175388336181640625e+8; > volatile _Complex double y = ctan (x); > return 0; > } > > If we get a test case

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Richard Biener
On Mon, 19 Nov 2018, Vincent Lefevre wrote: > On 2018-11-19 14:17:13 +0100, Niels Möller wrote: > > You might want to add an entry for "Exponent range" to the concept index > > in the manual. > > The concept index already has "Exponent", and the corresponding > paragraph is: > >An

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Richard Biener
On Mon, 19 Nov 2018, Niels Möller wrote: > Vincent Lefevre writes: > > > MPFR has a bounded (user configurable) exponent range, with underflow > > and overflow exceptions for out-of-range results, like in IEEE 754. > > Good! I didn't find that in the manual until I knew the phrase to search >

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Vincent Lefevre
On 2018-11-19 12:49:12 +0100, Richard Biener wrote: > I see. So I guess one issue might be that mpfr numbers have a > precision (mantissa bits?) but no restriction on the exponent? MPFR has a bounded (user configurable) exponent range, with underflow and overflow exceptions for out-of-range

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Richard Biener
On Mon, 19 Nov 2018, Torbjörn Granlund wrote: > Richard Biener writes: > > :/ But then with GCC we want deterministic behavior -- ISL > added some "computation budget" and error reporting if that was > taken up. Maybe gmp/mpfr/mpc could consider adding such a thing > (reporting budget

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Torbjörn Granlund
Richard Biener writes: :/ But then with GCC we want deterministic behavior -- ISL added some "computation budget" and error reporting if that was taken up. Maybe gmp/mpfr/mpc could consider adding such a thing (reporting budget overruns via a signal could be acceptable if the API

Re: Bug in gmp/mpfr/mpc, never ending ctan computation

2018-11-19 Thread Torbjörn Granlund
t...@gmplib.org (Torbjörn Granlund) writes: I simplified your test case using 1 as the real part and an integer for the imaginary part. With the real part set to 1, the computation finishes in about 10 seconds, with every doubling of it the runtime almost triples. (If my observation