https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78851
--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Vadim Zeitlin from comment #4)
> Thanks for the explanation! I didn't realize the template function below was
> smart enough to select __builtin_powil() automatically,
The template selects __builtin_powl, but gcc's optimizers know that when the
second argument has an integer value (in type long double), they can replace it
with __builtin_powil. One might complain that it only does this transformation
when the second argument is a constant, not for casts of integer variables to
long double.
> thought the comment was temporary because of the question in it: "What
> should the return type of pow(float,int) be?", which seemed to require an
> answer ("double"), but maybe it's just a figure of style I didn't understand.
I think that's the title of the DR (question mark included), check the issue
list to make sure.
> In practice, I definitely do not want to use -ffast-math (if anything, I'd
> rather use -fexcess-precision=standard but it's, unfortunately, not
> available for C++). And I can't change my (well, MinGW-w64's) libm. So,
> again, in this particular case, if I understand you correctly, it seems like
> I simply will have to live with the (very small, admittedly) loss of
> precision after migrating the existing code base from C++98 to C++11, right?
I think so.
