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Re: [PATCH] Optimise the fpclassify builtin to perform integer operations when possible
On Tue, 13 Sep 2016, Tamar Christina wrote:
> On 12/09/16 23:41, Joseph Myers wrote:
> > Are you making endianness assumptions - specifically, does the
> > reinterpretation as an integer require that WORDS_BIG_ENDIAN and
> > FLOAT_WORDS_BIG_ENDIAN are the same? If so, I think that's OK (in that
> > the only target where they aren't the same seems to be pdp11 which doesn't
> > use IEEE formats), but probably the code should check explicitly.
> >
> No, if I understood the question correctly then this should be ok,
> since I always access the float as an integer of equivalent precision.
> So a 64bit float will be addressed as a 64bit int.
My point is that there are theoretically systems where the order of words
in a 64-bit float is not the same as the order of words in a 64-bit
integer. Though it may be the case in practice that no such targets in
GCC use IEEE formats (and that pdp11 is the only target without all of
BYTES_BIG_ENDIAN, WORDS_BIG_ENDIAN and FLOAT_WORDS_BIG_ENDIAN the same).
--
Joseph S. Myers
joseph@codesourcery.com