Re: [PATCH 03/21] softfloat: add xtensa specialization for pickNaNMulAdd

[Richard Henderson]

On 7/6/20 4:47 PM, Max Filippov wrote:
> pickNaNMulAdd logic on Xtensa is the same as pickNaN when applied to
> the expression (a * b) + c. So with two pickNaN variants there must be
> two pickNaNMulAdd variants.

"Is the same as"?

I question the non-use of the infzero parameter.

When infzero, (a * b) = (Inf * 0), which will produce a default QNaN.  Your
sentence above would suggest that pickNaN is applied twice, so that if
use_first_nan, the default nan is chosen above any nan within c.

In addition, is the invalid flag raised for (Inf * 0) + NaN?  Does that happen
regardless of the use_first_nan setting, or does the whole operation 
short-circuit?


r~