Comment 7 for bug 645662

I had a brief look at softfloat. In principle, it should fix the
issue, but only if the FPU uses 80-bit double-extended-precision
internally. I guess the qemu FPU is still stuck at 64 bit double
internally and that does not cut it for some calculations.

Just to be sure, I re-tested the code from comment 1 and it does
work as expected with a real FPU.

Regards,
Arno

On Mon, Jan 23, 2017 at 22:20:18 CET, Thomas Huth wrote:
> Looks like your test code from comment #1 still prints out a wrong
> value, so the bug has apparently not been fixed by the FPU updates...
>
> ** Changed in: qemu
> Status: Incomplete => Triaged
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/645662
>
> Title:
> Python 3.1.2 math errors with Qemu 0.12.5
>
> Status in QEMU:
> Triaged
>
> Bug description:
> When doing the regression tests for Python 3.1.2 with Qemu 0.12.5, (Linux version 2.6.26-2-686 (Debian 2.6.26-25lenny1)),
> gcc (Debian 4.3.2-1.1) 4.3.2, Python compiled from sources within qemu,
> 3 math tests fail, apparently because the floating point unit is buggy. Qmeu was compiled from original sources
> on Debian Lenny with kernel 2.6.34.6 from kernel.org, gcc (Debian 4.3.2-1.1) 4.3.
>
> Regression testing errors:
>
> test_cmath
> test test_cmath failed -- Traceback (most recent call last):
> File "/root/tools/python3/Python-3.1.2/Lib/test/test_cmath.py", line 364, in
> self.fail(error_message)
> AssertionError: acos0034: acos(complex(-1.0000000000000002, 0.0))
> Expected: complex(3.141592653589793, -2.1073424255447014e-08)
> Received: complex(3.141592653589793, -2.1073424338879928e-08)
> Received value insufficiently close to expected value.
>
>
> test_float
> test test_float failed -- Traceback (most recent call last):
> File "/root/tools/python3/Python-3.1.2/Lib/test/test_float.py", line 479, in
> self.assertEqual(s, repr(float(s)))
> AssertionError: '8.72293771110361e+25' != '8.722937711103609e+25'
>
>
> test_math
> test test_math failed -- multiple errors occurred; run in verbose mode for deta
>
> =>
>
> runtests.sh -v test_math
>
> le01:~/tools/python3/Python-3.1.2# ./runtests.sh -v test_math
> test_math BAD
> 1 BAD
> 0 GOOD
> 0 SKIPPED
> 1 total
> le01:~/tools/python3/Python-3.1.2#
>
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--
Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: <email address hidden>
GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718
----
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