fenv.h is not implemented in Newlib

[kolerov]

fenv.h header file declares functions and macros for working with floating-point environment: exceptions, flags, etc. It's not critical, but some FP test suites use it. Thus, it may be useful to have it implemented.

[abrodkin]

@kolerov could you please elaborate a bit on real issues you've faced with?

[kolerov]

Here is an example of a FP test suite that uses fenv.h: http://www.tybor.com, tflt2int.c source file. However, I found that a lot of other test suites use it too. It's implemented in MWDT. Here is an error:

$ arc-elf32-gcc -mcpu=hs4x -mfpu=fpud_all -specs=nsim.specs -std=gnu11 TFLT2INT.C -lm -o TFLT2INT
TFLT2INT.C: In function 'void tst_02()':
TFLT2INT.C:667:14: error: 'FE_INVALID' was not declared in this scope
  667 |       if( !((FE_INVALID) & flags) ){\
      |              ^~~~~~~~~~

[abrodkin]

The same gets in the way on execution of the SuperTest. Compilation fails with things like:

TESTING: suite/C99/7/12/14/1/t1.c

   Test the isgreater macro
+++ stderr ++++++++++++++++++++++
t1.c:22:14: warning: '#pragma FENV_ACCESS' is not supported on this target - ignored [-Wignored-pragmas]
#pragma STDC FENV_ACCESS ON
             ^
t1.c:78:37: error: use of undeclared identifier 'FE_INEXACT'
        CVAL_VERIFY( ! fetestexcept(FE_INEXACT));
                                    ^
1 warning and 1 error generated.

   Compilation failed

RESULT: C99/7/12/14/1/t1.c                                               FAILED