[libc-commits] [libc] [libc][math] Implement double precision acos correctly rounded for all rounding modes. (PR #138308)

[via libc-commits]

zimmermann6 wrote:

I get a failure on a AMD EPYC 7282:
```
zimmerma at biscotte:~/svn/core-math$ CORE_MATH_CHECK_STD=true LIBM=/localdisk/zimmerma/llvm-project/build/projects/libc/lib/libllvmlibc.a EXTRA_CFLAGS="-DCORE_MATH_SUPPORT_ERRNO -DCORE_MATH_CHECK_INEXACT" ./check.sh acos
Running worst cases check in --rndn mode...
FAIL x=0x1.064abf8e63253p-1 ref=0x1.086f4ccb61e07p+0 z=0x1.086f4ccb61e08p+0
```

https://github.com/llvm/llvm-project/pull/138308