On Mon, Feb 7, 2022 at 11:02 AM Victor Stinner <vstin...@python.org> wrote:
> Hi Mark, > > Aha, good, you posted an email to python-dev, good :-) Last days, I > was trying to collect more data about this topic, especially find > platforms which *don't* support IEEE 754, before posting to > python-dev. > > Nowadays, outside museums, it's hard to find computers which don't > implement IEEE 754. > > * Since 1998, IBM S/390 supports IEEE 754. > * Compaq/DEC VAX didn't use IEEE 754, but are no longer built since > 2000 (you cant still use Python 3.10 if it can be built on it!) > * Some Cray computers like Cray SV1 (1998) don't implement IEEE 754, > but other Cray computers like Cray T90 (1995) implement IEEE 754. > > There are embedded devices with no hardware FPU: in this case, the FPU > is implemented in software. I expect it to implement IEEE 754. Is > CPython a good target for such small CPUs which have no hardware FPU? > MicroPython may better fit their needs. > > On the other side, all moderns CPU architectures support IEEE 754: > Intel x86, ARM, IBM Power and PowerPC, Compaq/DEC Alpha, HP PA-RISC, > Motorola 68xxx and 88xxx, SGI R-xxxx, Sun SPARC. > RISC-V also supports the 2008 IEEE-754 spec: https://riscv.org/technical/specifications/ . -Brett > > Sources: > > * > https://en.wikipedia.org/wiki/Floating-point_arithmetic#IEEE_754:_floating_point_in_modern_computers > * > https://stackoverflow.com/questions/2234468/do-any-real-world-cpus-not-use-ieee-754 > > > On Mon, Feb 7, 2022 at 7:25 PM Mark Dickinson <dicki...@gmail.com> wrote: > > - Should we require the presence of NaNs in order for CPython to build? > > - Should we require IEEE 754 floating-point for > CPython-the-implementation? > > In the past, when we deprecated the support for an old platform, we > didn't suddenly remove the code. We made sure that it's no longer > possible to build on it. So if anyone notices, it's easy to revert > (ex: remove the few lines in configure). > > Would it make sense to trigger a build error on plaforms which don't > support IEEE 754 in Python 3.11, and later decide if it's time to > remove the code in in Python 3.12? > > Well. If you ask *me*, I'm in favor of removing the code right now. If > someone needs to support a platform which doesn't support IEEE 754, > the support can be maintained *outside* the Python source code, as > external patches or as a Git fork, no? > > Honestly, I never got access to any machine which doesn't support IEEE > 754 (or nobody told me!). > > > > - Should we require IEEE 754 floating-point for Python-the-language? > > Right now, I have no opinion on this question. > > > > Note that on the current main branch there's a Py_NO_NAN macro that > builders can define to indicate that NaNs aren't supported, but the Python > build is currently broken if Py_NO_NAN is defined (see > https://bugs.python.org/issue46656). If the answer to the first question > is "No", then we need to fix the build under Py_NO_NAN. That's not a big > deal - perhaps a couple of hours of work. > > My comment on bpo-46656: "Python uses Py_NAN without "#ifdef Py_NAN" > guard since 2008. Building Python with Py_NO_NAN never worked. Nobody > reported such build failure in the last 14 years..." > > If anyone would try building/using Python on a platform without NAN, I > would expect that we would get a bug report or an email. I'm not aware > of anything like that, so it seems like nobody uses Python on such > platform. > > Victor > -- > Night gathers, and now my watch begins. It shall not end until my death. > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/PPVBMCKL5E2MVTWVFGSI4VTT6IAJ5QBF/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
_______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/WLYIMCEBOKWHYX4XIYLRRX4VHGZGMSJO/ Code of Conduct: http://python.org/psf/codeofconduct/
