| Message ID | 20200708222101.24568-4-jcmvbkbc@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | target/xtensa: implement double precision FPU | expand |
On 7/8/20 3:20 PM, Max Filippov wrote: > pickNaNMulAdd logic on Xtensa is to apply pickNaN to the inputs of the > expression (a * b) + c. However if default NaN is produces as a result > of (a * b) calculation it is not considered when c is NaN. > So with two pickNaN variants there must be two pickNaNMulAdd variants. > In addition the invalid flag is always set when (a * b) produces NaN. > > Cc: Peter Maydell <peter.maydell@linaro.org> > Cc: "Alex Bennée" <alex.bennee@linaro.org> > Cc: Richard Henderson <richard.henderson@linaro.org> > Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> > --- > Changes v2->v3: > - handle infzero case in pickNaNMulAdd properly and reword commit > message Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/fpu/softfloat-specialize.inc.c b/fpu/softfloat-specialize.inc.c index f519beca1b74..914deac46ecf 100644 --- a/fpu/softfloat-specialize.inc.c +++ b/fpu/softfloat-specialize.inc.c @@ -585,6 +585,32 @@ static int pickNaNMulAdd(FloatClass a_cls, FloatClass b_cls, FloatClass c_cls, } else { return 1; } +#elif defined(TARGET_XTENSA) + /* + * For Xtensa, the (inf,zero,nan) case sets InvalidOp and returns + * an input NaN if we have one (ie c). + */ + if (infzero) { + float_raise(float_flag_invalid, status); + return 2; + } + if (status->use_first_nan) { + if (is_nan(a_cls)) { + return 0; + } else if (is_nan(b_cls)) { + return 1; + } else { + return 2; + } + } else { + if (is_nan(c_cls)) { + return 2; + } else if (is_nan(b_cls)) { + return 1; + } else { + return 0; + } + } #else /* A default implementation: prefer a to b to c. * This is unlikely to actually match any real implementation.
pickNaNMulAdd logic on Xtensa is to apply pickNaN to the inputs of the expression (a * b) + c. However if default NaN is produces as a result of (a * b) calculation it is not considered when c is NaN. So with two pickNaN variants there must be two pickNaNMulAdd variants. In addition the invalid flag is always set when (a * b) produces NaN. Cc: Peter Maydell <peter.maydell@linaro.org> Cc: "Alex Bennée" <alex.bennee@linaro.org> Cc: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> --- Changes v2->v3: - handle infzero case in pickNaNMulAdd properly and reword commit message fpu/softfloat-specialize.inc.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)