Re: Stdio resource usage

[Rich Felker <dalias@libc.org>]

On Wed, Feb 20, 2019 at 05:37:59PM +0100, Szabolcs Nagy wrote:
> * Markus Wichmann <nullplan@gmx.net> [2019-02-20 16:47:40 +0100]:
> > On Wed, Feb 20, 2019 at 11:49:01AM +0100, Szabolcs Nagy wrote:
> > > aarch64 has 128 bit fp regs, so in principle future arch extension
> > > may add 128bit instructions without breaking abi. (which may happen
> > > if aarch64 gets adoption in supercomputers, e.g. powerpc64 did that)
> > > 
> > 
> > Say, if IEEE quad is causing problems, wouldn't it be possible to
> > compile a tool chain with long double == double for the time being?
> 
> of course if you are writing your own os you can do all sorts of things,
> but toolchains will follow the pcs abi in general which says that
> long double == ieee binary128
> 
> e.g. gcc does not have a config option to turn long double type into
> binary64 on aarch64. so you would have to maintain your own gcc fork.

One thing I think we could consider doing in musl is extract the long
double significand via the representation rather than math, and using
float_t rather than long double for the rounding probes. However I'm
not clear that most of the soft float machinery wouldn't already be
pulled in via the promotion of double args to long double for storage
in the arg structure... Also hex float would need new code I think.

Rich