Mark Dickinson <dicki...@gmail.com> added the comment:
> Sorry for the noise.
Not noise. I'd still be interested in understanding where this is coming
from; I seem to recall someone else having exactly the same experience
(reported bug, then found that it disappeared after a clean compile).
My best guess is that you somehow ended up in a situation where the math
module was using the x87 FPU for floating-point, while the interpreter
core was using SSE2. Is this possible?
Explanation: the x87 FPU has problems with double rounding (because it
uses 80-bit extended precision registers internally) while SSE2 doesn't. fsum
is a bit broken on systems with double rounding problems. So there's
a pair of lines in testFsum that look like:
if 1e16+2.0 != 1e16+2.9999:
return
These lines are supposed to skip all these tests on platforms with the
double rounding problem. But if the core is using SSE2 then the test will
fail and all the fsum tests will be executed, which is a problem if fsum
is using x87.
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue5593>
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