i386 and x86_64 fenv support

Joseph Myers joseph@codesourcery.com
Tue Aug 27 17:11:00 GMT 2019

On Tue, 27 Aug 2019, Joel Sherrill wrote:

> FWIW this moved up in importance because the x86_64 RTEMS toolchain
> won't build with the gcc/newlib master because libquadmath assumes the
> existence of the FE_TONEAREST since it the autoconf probe now sees
> we have fenv.h support now. This is probably a bug in this code since it
> can't assume a rounding mode is supported.

The rule in glibc is that architectures without support for rounding modes 
still define FE_TONEAREST, and return it from fegetround and accept it for 
fesetround, reflecting that to-nearest is the default (and only) rounding 

That is, only architectures that don't support to-nearest at all should 
fail to define FE_TONEAREST (and libquadmath doesn't support any such 
architectures anyway).

Joseph S. Myers

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