Mike Stump <mikest...@comcast.net> writes:
> On Jun 1, 2011, at 7:37 AM, Ian Lance Taylor wrote:
>>> One problem remains in the libgo testsuite: certain tests have to be
>>> compiled with -mieee, otherwise FPE is generated for unordered values.
>>> Any suggestions, where -mieee should be placed?
>>
>> That's an interesting question. I think that ideally we would like
>> -mieee to become the default when using gccgo.
>
> If the language spec requires it, then it should go into gcc/go. See
> java_post_options:
>
> static bool
> java_post_options (const char **pfilename)
> {
> /* Excess precision other than "fast" requires front-end
>
> support. */
> if (flag_excess_precision_cmdline == EXCESS_PRECISION_STANDARD
> && TARGET_FLT_EVAL_METHOD_NON_DEFAULT)
> sorry ("-fexcess-precision=standard for Java");
> flag_excess_precision_cmdline = EXCESS_PRECISION_FAST;
Sure, the Go frontend does stuff like that too. But of course the Go
frontend can't directly set -mieee, because -mieee is a machine
dependent option.
> so, you could check the setting and reset any flag that should be off
> or error out on incompatible flags. I'd like to think we could get
> more milage out of making a flag like -mieee be machine independent
> and then ports could just check the base flag for validating machine
> specific flags. Certainly alpha isn't the only port that has -mieee.
> There are likely to be very few flags promoted because of this, ieee
> being the most obvious example.
What I think you are suggesting here is another approach: Alpha should
set -mieee based on a machine-independent option, and then the Go
frontend can set that option instead. I'm fine with that approach too.
I don't think we currently have a machine-independent option which
corresponds to the Alpha -mieee option. According to the documentation,
-mieee does two things: adds support for NaN and infinity, and adds
support for denormal numbers. The first is the -fno-finite-math-only
option, which is actually the default for other targets. The second has
no machine independent option as far as I know.
Ian
