GeezerVison

Previous attempt in 2020: #17987

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For WASI, I skipped tests on the zero sign. It sounds too complicated to me to work around an implementation which doesn't implement IEEE 754-2008 correctly. Maybe we should even remove the function on this platform?

test_math failed on FreeBSD and FreeBSD 14.

test_importlib failed on RHEL7 Refleaks, Ubuntu NoGIL Refleaks, and MacOS M1 Refleaks NoGIL. But it's a known and unrelated leak: #116731

@mdickinson: Would you mind to review this PR?

I had to skip test_fma_zero_result() on FreeBSD and WASI platforms, because their libc fma() doesn't compute the zero sign properly: it doesn't respect IEEE 754-2008. I prefer to skip the test rather than removing the function on these platforms. What do you think?

I tried to compute the sign manually, but oh wow, rules to compute the sign a really complicated :-(

By the way, mathmodule.c contains a custom fma() implementation using "TripleLength":

/*
   The default implementation of dl_mul() depends on the C math library
   having an accurate fma() function as required by § 7.12.13.1 of the
   C99 standard. 

   The UNRELIABLE_FMA option is provided as a slower but accurate
   alternative for builds where the fma() function is found wanting.
   The speed penalty may be modest (17% slower on an Apple M1 Max),
   so don't hesitate to enable this build option.
    
   The algorithms are from the T. J. Dekker paper:
   A Floating-Point Technique for Extending the Available Precision
   https://csclub.uwaterloo.ca/~pbarfuss/dekker1971.pdf
*/

Was not it blocked by the fact that the standard fma() implementation on Windows did have unsatisfying quality, so we need to provide our own implementation?

In 2020, test_math failed on Windows 32-bit. It's no longer the case.

Thanks for the review @mdickinson and @erlend-aasland. I replaced IEEE 754-2008 with IEEE 754.

Can we open upstream issues, so that there's at least a chance that things will eventually be fixed on the underlying platforms? I'm less worried about FreeBSD, and much more interested in WASI, which could yet become mainstream.

I reported the issue to FreeBSD: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277783

This issue also appears on Android x86_64, though ARM64 is OK. And that's not surprising, because Android's libc was partly based on FreeBSD's.

I'll add a skip of this test in my next Android PR.

This issue also appears on Android x86_64, though ARM64 is OK. And that's not surprising, because Android's libc was partly based on FreeBSD's.

A fix was proposed for FreeBSD: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277783

If it's merged, maybe propose the same fix to Android libc? Is it bionic?

I'll add a skip of this test in my next Android PR.

The best would be to report the issue to Android if you skip the test ;-)

Yes, all Android devices use the Bionic libc. I'll watch the FreeBSD issue and maybe report it to Android once it's resolved.