On Thursday, 11 May 2017 at 02:05:11 UTC, Nikolay wrote:
I am porting LDC to NetBSD amd64, and I ask advice how to
handle real type. NetBSD has limited support for this type.
What is long double on NetBSD/amd64, 64-bit or full 80-bit? We
were talking about this when I was porting to Android/x86, where
long double is 64-bit but the FPU should support 80-bit. Iain
suggested just sticking to the ABI, ie using 64-bit if that's how
long double is defined (see next three comments after linked
comment):
https://github.com/dlang/phobos/pull/2150#issuecomment-42731651
This type exists, but standard library does not provide full
set of math functions for it (e.g. sinus, cosinus, and etc).
Currently I just forward all function calls to 64 bits version
counterparts, but in this case a set of unit tests are failing.
I see following approaches to handle this issue:
- Totally remove 80 bit real type from NetBSD port (make
real==double)
- Change tests and skip asserts for NetBSD
There is one additional approach: implement these functions in
druntime, but it is too big/massive work for me.
I wouldn't worry about it too much. If someone really needs
this, they will have to chip in. Dmd uses compiler intrinsics
for those trig functions, and I notice that they seem to just
call the native x86 asm instructions:
https://github.com/dlang/dmd/blob/master/src/ddmd/root/longdouble.c#L428
