RE: [PATCH v8 17/35] Hexagon (target/hexagon/fma_emu.[ch]) utility functions

[Taylor Simpson]

> -----Original Message-----
> From: Richard Henderson <richard.henderson@linaro.org>
> Sent: Sunday, February 14, 2021 5:15 PM
> To: Taylor Simpson <tsimpson@quicinc.com>; qemu-devel@nongnu.org
> Cc: philmd@redhat.com; alex.bennee@linaro.org; laurent@vivier.eu;
> ale@rev.ng; Brian Cain <bcain@quicinc.com>
> Subject: Re: [PATCH v8 17/35] Hexagon (target/hexagon/fma_emu.[ch])
> utility functions
>
> On 2/7/21 9:46 PM, Taylor Simpson wrote:
>
> Redundant with softfloat.  Is the default nan really -1?  I suppose then that
> hexagon does not distinguish QNaN from SNaN?
>
> You'll want to patch fpu/softfloat-specialize.c.inc for both of these choices:
> no_signaling_nans and parts_default_nan.

Yes, the default is really -1.  We do distinguish SNaN - when a SNaN is fed to 
an arithmetic operation, it raises the invalid flag and a QNaN is returned.

So, it looks like I'll need to patch parts_default_nan and parts_silence_nan as 
well as set default_nan_mode to 1.


> This is duplicating code from include/fpu/softfloat-macros.h, except for the
> wrapping to Int128.  That said, I don't think you should actually need this,
> or, frankly, the vast majority of the rest of your fp code.

OK, I will look into this.


Thanks,
Taylor