Re: #pragma STDC FENV_ACCESS ON

On Wed, Jul 17, 2024 at 01:30:39PM -0400, enh wrote:
> i see lib/msun/src/e_sqrtl.c has `#pragma STDC FENV_ACCESS ON`, but
> s_fma.c, s_fmaf.c, s_fmal.c, and s_nearbyint.c all use fesetround() or
> fesetenv() too --- shouldn't they also have the pragma?
> 
> (Android currently builds all of libm with that pragma, but (a) that
> seems like a big hammer and (b) afaict upstream [you] don't, so this
> is potentially causing problems^W^Wallowing the compiler to cause
> problems for you?)

Some of the compilers, which that are used to compile FreeBSD,
do not support "#pragma STDC FENV_ACCESS ON".

#include <stdio.h>
#include <math.h>

#pragma STDC FENV_ACCESS ON

int
main(void)
{
   double x = 1, y = 3;
   printf ("x _ y = %la\n", x + y);
   return 0;
}

% gcc13 -c -Wall a.c
.c:5: warning: ignoring '#pragma STDC FENV_ACCESS' [-Wunknown-pragmas]
    5 | #pragma STDC FENV_ACCESS ON
      | 

-- 
Steve