fix emu128 reduction with infinities. thanks @yohanchatelain, fixes #…

…2434

PiperOrigin-RevId: 713663844

hwy/ops/emu128-inl.h

@@ -2916,17 +2916,38 @@ HWY_API T ReduceSum(D d, VFromD<D> v) {
   }
   return sum;
 }
+
+namespace detail {
+template <class D, typename T = TFromD<D>, HWY_IF_FLOAT_OR_SPECIAL(T)>
+T InitReduceMin(D d) {
+  return GetLane(Inf(d));
+}
+template <class D, typename T = TFromD<D>, HWY_IF_NOT_FLOAT_NOR_SPECIAL(T)>
+T InitReduceMin(D d) {
+  return HighestValue<T>();
+}
+
+template <class D, typename T = TFromD<D>, HWY_IF_FLOAT_OR_SPECIAL(T)>
+T InitReduceMax(D d) {
+  return -GetLane(Inf(d));
+}
+template <class D, typename T = TFromD<D>, HWY_IF_NOT_FLOAT_NOR_SPECIAL(T)>
+T InitReduceMax(D d) {
+  return LowestValue<T>();
+}
+}  // namespace detail
+
 template <class D, typename T = TFromD<D>, HWY_IF_REDUCE_D(D)>
 HWY_API T ReduceMin(D d, VFromD<D> v) {
-  T min = HighestValue<T>();
+  T min = detail::InitReduceMin(d);
   for (size_t i = 0; i < MaxLanes(d); ++i) {
     min = HWY_MIN(min, v.raw[i]);
   }
   return min;
 }
 template <class D, typename T = TFromD<D>, HWY_IF_REDUCE_D(D)>
 HWY_API T ReduceMax(D d, VFromD<D> v) {
-  T max = LowestValue<T>();
+  T max = detail::InitReduceMax(d);
   for (size_t i = 0; i < MaxLanes(d); ++i) {
     max = HWY_MAX(max, v.raw[i]);
   }