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Re: float128 in libstdc++

On 25.06.2017 12:30, Martin Husemann wrote:
> On Sat, Jun 24, 2017 at 04:03:49PM +0200, Kamil Rytarowski wrote:
>> arch/sparc64/c++config.h:/* #undef _GLIBCXX_USE_FLOAT128 */
> Something is definitively strange here (as Joerg noted). We use 128 bit
> long doubles via softfloat on sparc64. We should actually offer the
> hardfloat version too and fix all fallout from the emulator (if there
> are any left), but last tests showed this to be slower.

__float128 is not listed for sparc64 hardware in the GCC documentation:

>> SYSV ABI AMD64 notes float128 optionally and software emulated for at
>> least order hardware.
> What amd64 cpus support it in hardware (or which of the strange feature
> bit acronyms matches it)? Of course we can not make the library features
> depend on runtime cpu support detection.

Right now I don't know any x86_64 cpus that can do __float128 in
hardware, at least few years ago there were none.

> Martin

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