According to ISO C23 (7.6.4.4), fesetexcept is supposed to set
floating-point exception flags without raising a trap (unlike
feraiseexcept, which is supposed to raise a trap if feenableexcept
was called with the appropriate argument).
The flags can be set in the 387 unit or in the SSE unit. When we need
to clear a flag, we need to do so in both units, due to the way
fetestexcept is implemented.
When we need to set a flag, it is sufficient to do it in the SSE unit,
because that is guaranteed to not trap. However, on i386 CPUs that have
only a 387 unit, set the flags in the 387, as long as this cannot trap.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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