80 bit floating point emulator

[kinke]

On Sunday, 6 February 2022 at 13:10:46 UTC, Ola Fosheim Grøstad 
wrote:
> Yes, which is why I wonder why people would want 80 bits in 
> software.

This is for the DMD frontend, e.g., if DMD is built as a native 
Apple AArch64 program (with 64-bit native `real` - as an 
Apple-divergence; all other AArch64 targets use 128-bit quadruple 
precision AFAIK), but limited to cross-compiling to x86 (as only 
arch supported by the DMD backend). It still has to parse and 
perform CTFE computations in 80-bit extended precision to yield 
the same results a native x86-DMD would.