[LLVMdev] IEEE 754-2008 | ISO/IEC TR 18037

Tim Northover t.p.northover at gmail.com
Mon Sep 9 12:02:34 PDT 2013

> This will come in handy if you do not have a floating point unit. Also for
> speed in some cases.
> To be generic as possible it might be good to have this.

The goal isn't really maximum generality, but support for languages
that people care about. Currently that's mostly C and C++, with a
smattering of features for some others.

But features almost never get added speculatively. At the very least
someone needs to care enough to write a patch, and generally we want
to be reasonably sure that it'll be maintained.

> BTW, in the doc I was reading there was not mention about Quad size numbers,
> decimal numbers and extended precision numbers.
> http://llvm.org/docs/LangRef.html#type-system

There appear to be numerous mentions of fp128 (which is IEEE
quad-precision), ppc_fp128 and x86_fp80 (at least one of which
probably qualifies as extended precision).

Of course, those types have much more limited support in the backends
than standard float and double. AArch64 should support fp128, and
obviously ppc and x86 for their specific formats.


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