The re-factoring of div_floats changed the order of checking meaning
an operation like -inf/0 erroneously raises the divbyzero flag.
IEEE-754 (2008) specifies this should only occur for operations
on finite operands.
We fix this by moving the check on the dividend being Inf/0 to
before the divisor is zero check.
Cc: Bastian Koppelmann <kbast...@mail.uni-paderborn.de>
Cc: Alex Bennée <alex.ben...@linaro.org>
Cc: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
fpu/softfloat.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index fb8663f59e..ba6e654050 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -1146,15 +1146,20 @@ static FloatParts div_floats(FloatParts a, FloatParts
b, float_status *s)
a.cls = float_class_dnan;
return a;
}
- /* Div 0 => Inf */
+ /* Inf / x */
+ if (a.cls == float_class_inf) {
+ a.sign = sign;
+ return a;
+ }
+ /* x / 0 => Inf */
if (b.cls == float_class_zero) {
s->float_exception_flags |= float_flag_divbyzero;
a.cls = float_class_inf;
a.sign = sign;
return a;
}
- /* Inf / x or 0 / x */
- if (a.cls == float_class_inf || a.cls == float_class_zero) {
+ /* 0 / x */
+ if (a.cls == float_class_zero) {
a.sign = sign;
return a;
}
--
2.14.3
