Re: [PATCH 08/17] RISC-V: Generic <math.h> and soft-fp Routines

[Joseph Myers <joseph at codesourcery dot com>]

On Wed, 24 Jan 2018, Palmer Dabbelt wrote:

> FIXME: add ieee745/soft-fp via a riscv/soft-fp directory.

You need to remove that FIXME (and, in general, update patch descriptions 
when sending new versions of a patch series - though in this case it 
doesn't matter so much, as it makes sense for the final commit of a new 
port to go in a single commit, not lots of separate commits of different 
pieces that don't work without each other, so an overall commit message is 
what's needed at that point anyway).

> +/* Despite not supporting trapping exceptions, we support setting
> +   floating-point exception flags on hard-float targets.  These are not
> +   supported on soft-float targets.  */
> +#if __riscv_flen == 0
> +#define EXCEPTION_TESTS_float 0
> +#define EXCEPTION_TESTS_double        0
> +#endif

Missing preprocessor indentation, "# define".

> +/* We don't support the Q extension yet, so long double is always soft float
> + * and therefor doesn't support exceptions.  */
> +#define EXCEPTION_TESTS_long_double   0

That's not accurate.  The EXCEPTION_TESTS_long_double definition should be 
inside the same conditional as the others - the RISC-V sfp-machine.h, in 
both glibc and libgcc, already handles making software floating-point 
types use the hardware exceptions and rounding modes when those exist.

(I expect that if you completed a soft-float test run you'd find that 
ROUNDING_TESTS_* definitions, similar to those on other ports, are also 
needed inside that conditional, to disable tests of rounding modes other 
than FE_TONEAREST for soft-float.)

-- 
Joseph S. Myers
joseph@codesourcery.com