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Re: Start implementing -frounding-math
On Thu, 8 Aug 2019, Joseph Myers wrote:
On Thu, 8 Aug 2019, Marc Glisse wrote:
FENV_ROUND (and FENV_DEC_ROUND) shouldn't be that hard, given the
On the glibc side I expect it to be a lot of work, it seems to require a
correctly rounded version of all math functions...
No, it doesn't. 18661-4 reserves cr* names for correctly rounded
functions; most of the non-cr* names are not bound to the IEEE operations
and so have no specific accuracy requirements, with FENV_ROUND they just
need to behave the same as if the relevant dynamic rounding mode were set
(via the compiler temporarily setting it before calling the function).
And since glibc just ignores the rounding mode, that's no constraint at
all, at least on that platform. ok.