Fixed underflow error

src/halfvec.c

@@ -164,7 +164,7 @@ HalfToFloat4(half num)
 /*
  * Convert a float4 to a half
  */
-static half
+half
 Float4ToHalfUnchecked(float num)
 {
 #ifdef FLT16_SUPPORT

src/halfvec.h

@@ -36,5 +36,6 @@ typedef struct HalfVector
 HalfVector *InitHalfVector(int dim);
 float		HalfToFloat4(half num);
 half		Float4ToHalf(float num);
+half		Float4ToHalfUnchecked(float num);
 
 #endif

src/hnswutils.c

@@ -199,7 +199,10 @@ HnswNormValue(FmgrInfo *procinfo, Oid collation, Datum *value, int type)
 			HalfVector *result = InitHalfVector(v->dim);
 
 			for (int i = 0; i < v->dim; i++)
-				result->x[i] = Float4ToHalf(HalfToFloat4(v->x[i]) / norm);
+			{
+				/* TODO Fix */
+				result->x[i] = Float4ToHalfUnchecked(HalfToFloat4(v->x[i]) / norm);
+			}
 
 			*value = PointerGetDatum(result);
 		}