[m-rev.] for review: new runtime option for setting fp rounding mode

[Julien Fischer]

On Mon, 3 Nov 2008, Paul Bone wrote:

> On Tue, Oct 28, 2008 at 07:07:44PM +1100, Julien Fischer wrote:
>> Index: runtime/mercury_conf.h.in
>> ===================================================================
>> RCS file:
>> /home/mercury/mercury1/repository/mercury/runtime/mercury_conf.h.in,v
>> retrieving revision 1.61
>> diff -u -r1.61 mercury_conf.h.in
>> --- runtime/mercury_conf.h.in	22 Jan 2008 02:36:37 -0000	1.61
>> +++ runtime/mercury_conf.h.in	28 Oct 2008 06:56:42 -0000
>> @@ -133,6 +133,7 @@
>>  ** 	MR_HAVE_PTHREAD_H	we have <pthread.h>
>>  **	MR_HAVE_TIME_H		we have <time.h>
>>  ** 	MR_HAVE_SPAWN_H		we have <spawn.h>
>> +**	MR_HAVE_FENV_H		we have <fenv.h>
>>  */
>>  #undef	MR_HAVE_SYS_SIGINFO_H
>>  #undef	MR_HAVE_SYS_SIGNAL_H
>> @@ -159,6 +160,7 @@
>>  #undef	MR_HAVE_PTHREAD_H
>>  #undef	MR_HAVE_TIME_H
>>  #undef	MR_HAVE_SPAWN_H
>> +#undef  MR_HAVE_FENV_H
>
> The indenting looks different here.  Should it use tabs rather than
> spaces?
>
>>
>>  /*
>>  ** MR_HAVE_POSIX_TIMES is defined if we have the POSIX
>> @@ -256,6 +258,7 @@
>>  **	MR_HAVE_PUTENV		we have the putenv() function.
>>  **	MR_HAVE__PUTENV		we have the _putenv() function.
>>  **	MR_HAVE_POSIX_SPAWN	we have the posix_spawn() function.
>> +**	MR_HAVE_FESETROUND	we have the fesetround() function.
>>  */
>>  #undef	MR_HAVE_GETPID
>>  #undef	MR_HAVE_SETPGID
>> @@ -316,6 +319,7 @@
>>  #undef	MR_HAVE_PUTENV
>>  #undef	MR_HAVE__PUTENV
>>  #undef	MR_HAVE_POSIX_SPAWN
>> +#undef  MR_HAVE_FESETROUND
>>
>
> And here.

I'll check these before committing.

>> Index: runtime/mercury_wrapper.c
>> ===================================================================
>> RCS file:
>> /home/mercury/mercury1/repository/mercury/runtime/mercury_wrapper.c,v
>> retrieving revision 1.193
>> diff -u -r1.193 mercury_wrapper.c
>> --- runtime/mercury_wrapper.c	16 Sep 2008 07:52:27 -0000	1.193
>> +++ runtime/mercury_wrapper.c	28 Oct 2008 07:38:46 -0000
>> @@ -1899,6 +1905,70 @@
>>  #endif
>>                  break;
>>
>> +            case MR_FP_ROUNDING_MODE:
>> +#if defined(MR_HAVE_FENV_H) && defined(MR_HAVE_FESETROUND)
>> +                {
>> +                    int     rounding_mode;
>> +
>> +                    /*
>> +                    ** Particular rounding modes are only supported if the
>> +                    ** corresponding FE_* macro is defined.  The four
>> below are
>> +                    ** the ones from C99.  C99 says that these macros
>> +                    ** should expand to a nonnegative value, so we use a
>> negative value
>> +                    ** to indicate that the selected rounding mode is not
>> supported by
>> +                    ** the system.
>> +                    */
>> +                    if (MR_streq(MR_optarg, "downward")) {
>> +                        #if defined(FE_DOWNWARD)
>> +                            rounding_mode = FE_DOWNWARD;
>> +                        #else
>> +                            rounding_mode = -1;
>> +                        #endif
>> +                    } else if (MR_streq(MR_optarg, "upward")) {
>> +                        #if defined(FE_UPWARD)
>> +                            rounding_mode = FE_UPWARD;
>> +                        #else
>> +                            rounding_mode = -1;
>> +                        #endif
>> +                    } else if (MR_streq(MR_optarg, "toward_zero")) {
>> +                        #if defined(FE_TOWARDZERO)
>> +                            rounding_mode = FE_TOWARDZERO;
>> +                        #else
>> +                            rounding_mode = -1;
>> +                        #endif
>> +                    } else if (MR_streq(MR_optarg, "to_nearest")) {
>> +                        #if defined(FE_TONEAREST)
>> +                            rounding_mode = FE_TONEAREST;
>> +                        #else
>> +                            rounding_mode = -1;
>> +                        #endif
>> +                    } else {
>> +                        MR_usage();
>> +                    }
>> +
>> +                    if (rounding_mode < 0) {
>> +                        printf("Mercury runtime: the selected rounding
>> mode is "
>> +                            "not supported by this system.\n");
>> +                        fflush(stdout);
> Do you need to flush stdout before exiting anyway?  doesn't the C
> library handle this?  or does our runtime system prevent the C library
> from doing this.
>
> Should these errors go to stderr instead?

The above is consistent with the way error messages for other runtime options
are handled.

Julien.
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