Peter Maydell <peter.mayd...@linaro.org> writes: > It is implementation defined whether a multiply-add of > (0,inf,qnan) or (inf,0,qnan) raises InvalidaOperation or > not, so we let the target-specific pickNaNMulAdd function > handle this. This means that we must do the "return the > default NaN in default NaN mode" check after the call, > not before. Correct the ordering, and restore the comment > from the old propagateFloat64MulAddNaN() that warned about > this corner case. > > This fixes a regression from 2.11 for Arm guests where we would > incorrectly fail to set the Invalid flag for these cases. > > Cc: qemu-sta...@nongnu.org > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Alex Bennée <alex.ben...@linaro.org> Tested-by: Alex Bennée <alex.ben...@linaro.org> > --- > fpu/softfloat.c | 52 ++++++++++++++++++++++++++++--------------------- > 1 file changed, 30 insertions(+), 22 deletions(-) > > diff --git a/fpu/softfloat.c b/fpu/softfloat.c > index 70e0c40a1c..8401b37bd4 100644 > --- a/fpu/softfloat.c > +++ b/fpu/softfloat.c > @@ -602,34 +602,42 @@ static FloatParts pick_nan(FloatParts a, FloatParts b, > float_status *s) > static FloatParts pick_nan_muladd(FloatParts a, FloatParts b, FloatParts c, > bool inf_zero, float_status *s) > { > + int which; > + > if (is_snan(a.cls) || is_snan(b.cls) || is_snan(c.cls)) { > s->float_exception_flags |= float_flag_invalid; > } > > - if (s->default_nan_mode) { > - a.cls = float_class_dnan; > - } else { > - switch (pickNaNMulAdd(is_qnan(a.cls), is_snan(a.cls), > - is_qnan(b.cls), is_snan(b.cls), > - is_qnan(c.cls), is_snan(c.cls), > - inf_zero, s)) { > - case 0: > - break; > - case 1: > - a = b; > - break; > - case 2: > - a = c; > - break; > - case 3: > - a.cls = float_class_dnan; > - return a; > - default: > - g_assert_not_reached(); > - } > + which = pickNaNMulAdd(is_qnan(a.cls), is_snan(a.cls), > + is_qnan(b.cls), is_snan(b.cls), > + is_qnan(c.cls), is_snan(c.cls), > + inf_zero, s); > > - a.cls = float_class_msnan; > + if (s->default_nan_mode) { > + /* Note that this check is after pickNaNMulAdd so that function > + * has an opportunity to set the Invalid flag. > + */ > + a.cls = float_class_dnan; > + return a; > } > + > + switch (which) { > + case 0: > + break; > + case 1: > + a = b; > + break; > + case 2: > + a = c; > + break; > + case 3: > + a.cls = float_class_dnan; > + return a; > + default: > + g_assert_not_reached(); > + } > + a.cls = float_class_msnan; > + > return a; > } -- Alex Bennée